Flow sensing device

Abstract

Methods and apparatuses associated with flow sensing devices are provided. An exemplary flow sensing device includes a flow top cap component and a sensor component. The flow top cap component or the sensor component can include a heater element. The flow top cap component can at least partially define a flow channel configured for media to flow therethrough. The heater element can be orthogonal or perpendicular to the flow channel. The sensor component can include at least one thermal sensing element disposed upstream of the heater element and at least one thermal sensing element disposed downstream of the heater element. The sensor component can include two or more thermal sensing elements disposed in the upstream direction or the downstream direction of the heater element. Thermal sensing elements can be spaced apart by different distances from the heater element to increase accuracy and precision of flow measurements at low flow rates.

Description

Background Technology

[0001] Flow sensors can be used to measure the flow rate and / or quantity of moving liquids or gases and can be implemented in a variety of applications. For example, a flow sensor can be part of a system for measuring and / or controlling the dosage of a liquid or gas.

[0002] However, existing flow sensors are plagued by challenges and limitations. For example, existing flow sensors cannot provide accurate and economical measurements of low liquid flow rates using microelectronic systems with a small system footprint. Summary of the Invention

[0003] Exemplary flow sensing devices can be provided based on various examples of this disclosure.

[0004] In some examples, exemplary flow sensing devices may include a flow top cover component and a sensor component.

[0005] In some examples, the flow top cover component or sensor component may include a heating element disposed in a first layer of the flow top cover component or sensor component.

[0006] In some examples, the sensor component may include at least one thermal sensing element disposed in a second layer of the sensor component.

[0007] In some examples, the flow top cover component may be bonded to a first surface of the sensor component to form a flow channel. In some examples, the first layer and the second layer may be non-coplanar and separated by the flow channel. In some embodiments, the flow top cover component may completely define the flow channel.

[0008] In some examples, the flow top cover component may include a flow channel portion on a second surface of the flow top cover component. In some examples, the flow channel portion and the first surface of the sensor component may form a first portion of the flow channel.

[0009] In some examples, the flow top cover component may include a first opening and a second opening. In some examples, the first and second openings may be connected to a flow channel portion on a second surface of the flow top cover component.

[0010] In some examples, the flow cover component may be configured to receive a flow medium, such as a fluid, liquid, suspension, etc., through a first opening. In some examples, the flow medium may travel through a flow channel. In some examples, the flow medium may exit the flow cover component through a second opening.

[0011] In some examples, the first part of the flow channel may include multiple sidewalls extending along the central axis of the flow channel.

[0012] In some examples, a portion of the second surface of the flow top cover component may be bonded to the third surface of the attachment component. In some examples, a fourth surface of the attachment component may be bonded to a portion of the first surface of the sensor component. In some examples, the flow top cover component, the sensor component, and the attachment component may form a first portion of a flow channel.

[0013] In some examples, at least one thermal sensing element may include a first thermal sensing element and a second thermal sensing element. In some examples, the second thermal sensing element may be positioned downstream of the first thermal sensing element.

[0014] In some examples, the flow top cover component may include a cavity portion on a third surface of the flow top cover component opposite to the second surface. In some examples, a heating element may contact the cavity portion.

[0015] In some examples, at least one thermal sensing element may include at least one thermopile element. In some examples, the sensor component may also include an insulating layer disposed between at least one plate element and at least one thermopile element.

[0016] In some examples, at least one thermal sensing element may include at least one resistor element. In some examples, the sensor component may also include an insulating layer disposed between at least one plate element and at least one resistor element.

[0017] In some examples, an exemplary flow sensing device may include one or more first thermal sensing elements configured at a first distance from a heating element. In some examples, a first voltage difference may be established between the inlet and outlet of the one or more first thermal sensing elements based on a temperature change.

[0018] In some examples, an exemplary flow sensing device may include one or more second thermal sensing elements configured at a second distance from the heating element. In some examples, the second distance may be greater than the first distance. In some examples, a second voltage difference may be established between the inlet and outlet of the one or more second thermal sensing elements based on temperature changes.

[0019] In some examples, the first voltage difference and the second voltage difference indicate the flow rate of fluid in a flow channel disposed adjacent to the heating element, the one or more first thermal sensing elements and the one or more second thermal sensing elements.

[0020] In some examples, the one or more first thermal sensing elements and the one or more second thermal sensing elements are disposed on the same side of the heating element. In some examples, all of the one or more first thermal sensing elements and the one or more second thermal sensing elements are located upstream or downstream of the heating element.

[0021] In some examples, the flow sensing device may also include circuitry configured to at least: determine a sum of a first voltage difference and a second voltage difference; and compare the sum of the first voltage difference and the second voltage difference with a calibration curve that correlates a plurality of summed voltage differences with corresponding flow rates.

[0022] In some examples, the flow sensing device may also include a flow top cover component that at least partially defines the flow channel, wherein the flow channel is configured to deliver fluid through it, and the flow channel is disposed along a first axis.

[0023] In some examples, the flow sensing device may also include a heating element configured to release a predetermined amount of heat energy. In some examples, the heating element may be positioned along a second axis that is at least substantially perpendicular to the first axis.

[0024] In some examples, the one or more first thermal sensing elements or the one or more second thermal sensing elements may include at least one of the following: a resistor, a resistive bridge, a resistive Wheatstone bridge, a diode, a thermocouple, or a thermopile.

[0025] In some examples, the one or more first thermal sensing elements are positioned at a first distance from the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel, and the one or more second thermal sensing elements are positioned at a second distance from the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel. In some examples, the first and second distances from the heating element are different.

[0026] In some examples, the flow sensor may also include one or more third thermal sensing elements and one or more fourth thermal sensing elements, the one or more third thermal sensing elements being positioned at a first distance from the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel, and the one or more fourth thermal sensing elements being positioned at a second distance from the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel.

[0027] In some examples, the flow sensor device may include a sensor component that includes a top surface and defines an inner cavity.

[0028] In some examples, the flow sensor device may include a membrane disposed on a portion of the top surface of a sensor component, wherein the one or more first thermal sensing elements and the one or more second thermal sensing elements are disposed on or within the membrane.

[0029] In some examples, the flow sensor device may include a flow top cover that at least partially defines a flow channel. In some examples, the flow top cover may be operatively coupled to a sensor die such that the flow channel is adjacent to the one or more first thermal sensing elements and the one or more second thermal sensing elements.

[0030] In some examples, each of the one or more first thermal sensing elements and the one or more second thermal sensing elements may include a first thermocouple material operatively coupled to a thermocouple contact at a first end, and a second thermocouple material operatively coupled to a thermocouple contact at a first end.

[0031] In some examples, the second end of the first thermocouple material is positioned at the first distance from the heating element, and the second end of the second thermocouple material extends beyond the edge of the membrane.

[0032] In some examples, the flow channel has a height or diameter between about 1 μm and about 500 μm. In some examples, the flow sensor is used to measure flow rates between about 0.5 mL / h and about 1,000 mL / h. In some examples, the heating element has a width between about 5 μm and about 100 μm. In some examples, the heating element has a length between about 50 μm and about 1,000 μm.

[0033] In some examples, the one or more first thermal sensing elements are configured to be electrically coupled to the one or more second thermal sensing elements. In some examples, the one or more first thermal sensing elements and the one or more second thermal sensing elements are configured to be electrically coupled together in series.

[0034] In some examples, the first distance between the second end of the first thermocouple material and the center of the heating element is between about 25 μm and about 75 μm. In some examples, the second distance between the second end of the second thermocouple material and the center of the heating element is between about 125 μm and about 175 μm.

[0035] In some examples, the first distance between the second end of the first thermocouple material and the center of the heating element is between about 25 μm and about 70 μm, between about 25 μm and about 65 μm, between about 25 μm and about 60 μm, between about 25 μm and about 55 μm, between about 25 μm and about 50 μm, between about 25 μm and about 45 μm, between about 25 μm and about 40 μm, between about 25 μm and about 35 μm, between about 30 μm and about 75 μm, between about 35 μm and about 75 μm, between about 40 μm and about 75 μm, between about 45 μm and about 75 μm, between about 50 μm and about 75 μm, between about 55 μm and about 75 μm, and between about 60 μm and about 75 μm, including all values ​​and ranges between them.

[0036] According to some examples, a flow sensor may be provided, which includes a flow top cover component that at least partially defines a flow channel. In some examples, the flow channel is configured to deliver fluid through it. In some examples, the flow channel may be positioned substantially along a first axis.

[0037] In some examples, the flow sensor may also include a sensor component that includes a top surface and defines an inner cavity. In some examples, a flow top cover is operatively coupled to at least a portion of the top surface of the sensor component.

[0038] In some examples, the sensor component may also include a heating element disposed on or within the sensor component. In some examples, the heating element may be disposed along a second axis that is at least substantially perpendicular to the first axis.

[0039] In some examples, the flow sensor may further include a first thermal sensing element disposed on or within the sensor component along the second axis and spaced a first distance from the heating element in a first direction. In some examples, a first output voltage can be measured at the outlet of the first thermal sensing element.

[0040] In some examples, the flow sensor may also include a second thermal sensing element disposed on or within the sensor component along the second axis and spaced apart from the heating element by a second distance in a first direction, the second distance being greater than the first distance. In some examples, a second output voltage can be measured at the outlet of the second thermal sensing element.

[0041] In some examples, the flow sensor may also include a third thermal sensing element disposed on or within the sensor component along the second axis and spaced apart from the heating element by a first distance in a second direction opposite to the first direction. In some examples, a third output voltage can be measured at the outlet of the third thermal sensing element.

[0042] In some examples, the flow sensor may also include a fourth thermal sensing element, which is disposed on or within the sensor component along the second axis and spaced a second distance from the heating element along the second direction. In some examples, a fourth output voltage can be measured at the outlet of the fourth thermal sensing element.

[0043] In some examples, the voltage difference indicates the flow rate of fluid through the flow channel. In some examples, the voltage difference may include the difference between the sum of the first and second output voltages and the sum of the third and fourth output voltages.

[0044] In some examples, one or more of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element include at least one of the following: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple, or a thermopile.

[0045] In some examples, at least a portion of each of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element is disposed on or in a membrane disposed on or in the sensor component, wherein each of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element includes a first thermocouple material operatively coupled to a thermocouple contact at a first end, and a second thermocouple material operatively coupled to a thermocouple contact at a first end.

[0046] In some examples, the second end of the first thermocouple material is positioned at the first distance from the heating element, and the second end of the second thermocouple material extends beyond the edge of the membrane. In some examples, the first distance from the heating element is between about 1 μm and about 25 μm. In some examples, the second distance from the heating element is between about 50 μm and about 150 μm.

[0047] In some examples, the membrane may comprise one or more first materials, and the sensor components may comprise one or more second materials. In some examples, the one or more first materials may be at least substantially thermally and / or electrically insulating. In some examples, the one or more second materials may be at least substantially thermally and / or electrically conductive. In some examples, the membrane itself may be at least substantially thermally and electrically insulating. In some examples, the heater element and the thermal sensing element may be at least substantially thermally and electrically conductive. In some examples, the sensor die itself may be at least substantially thermally conductive.

[0048] In some examples, the flow channel has a height, width, or diameter between about 1 μm and about 500 μm. In some examples, the heating element has a width between about 5 μm and about 100 μm. In some examples, the heating element has a length between about 50 μm and about 1,000 μm.

[0049] Based on various examples of this disclosure, exemplary methods for measuring the flow rate of fluid in a flow path can be provided.

[0050] In some examples, the method may include providing a first current having a first voltage to a heating element positioned adjacent to the flow path. In some examples, the heating element may be generally cylindrical or rectangular in shape and may be positioned perpendicular to the flow path.

[0051] In some examples, the method may further include providing a second current having a second voltage to an inlet of a first thermal sensing element, the inlet of the first thermal sensing element being spaced a first distance from the long edge of the heating element.

[0052] In some examples, the method may further include providing a third current having a third voltage to an inlet of a second thermal sensing element, the inlet of which is spaced a second distance from the long edge of the heating element. In some examples, the second distance is greater than the first distance.

[0053] In some examples, the first voltage, the second voltage, and the third voltage may be the same or different. In some examples, the second voltage and the third voltage may be the same, while the first voltage may be different. In some examples, at least one of the first voltage, the second voltage, and the third voltage may change over time or during one or more different time periods. In other examples, at least one of the first voltage, the second voltage, and the third voltage may remain constant or substantially constant over time or during one or more different time periods.

[0054] In some examples, the method may also include measuring the outlet voltage at the respective outlets of the first and second thermal sensing elements.

[0055] In some examples, the method may also include determining the flow rate of fluid in the flow path based on the outlet voltage.

[0056] In some examples, the flow rate can be determined by the difference between the upstream and downstream thermopile voltages. For instance, bidirectional flow rates can be obtained by comparing the upstream and downstream voltages.

[0057] In some examples, for flow sensor devices that include a sensing element on one side of the heating element (e.g., only in the downstream direction), it may be advantageous to position the sensing element downstream of the heating element compared to upstream, at least because upstream temperature changes can occur over small flow rate variations and typically do not change further at higher flow rates or result in significantly different temperature variations at higher flow rates. Conversely, downstream sensors may be able to sense temperature (and therefore flow rate) variations over a much larger temperature and flow range because they can be heated more than upstream sensors lose. In some examples, including multiple upstream sensing elements and multiple downstream sensing elements may be advantageous.

[0058] In some examples, the first current causes the heating element to transfer heat energy toward the flow path, the first thermal sensing element, and the second thermal sensing element.

[0059] In some examples, the outlet voltage at the respective outlets of the first and second thermal sensing elements indicates the flow rate.

[0060] Based on various examples of this disclosure, exemplary methods for manufacturing flow sensing devices can be provided.

[0061] In some examples, the method may include a flow top cover component that provides a flow path that partially defines a flow path oriented along a first axis.

[0062] In some examples, the method may further include providing a sensor component including a heating element having a substantially rectangular or cylindrical shape factor, the heating element being oriented along a second axis substantially orthogonal to the first axis, the sensor component further including at least a first thermal sensing element and a second thermal sensing element, the first thermal sensing element being positioned at a first distance from the heating element along the first axis and the second thermal sensing element being positioned at a second distance from the heating element along the first axis.

[0063] In some examples, the method may also include bonding a flow top cover component to a first surface of a sensor component to form a flow channel therebetween.

[0064] In one exemplary embodiment, an apparatus for sensing fluid flow rate is provided. The apparatus may include a flow sensing device comprising a heating structure having a centerline. The flow sensing device may further include a thermopile. At least a portion of the thermopile may be disposed on the heating structure. The thermopile may include a first thermocouple having a first thermocouple junction disposed upstream of the centerline of the heating structure. The thermopile may further include a second thermocouple having a second thermocouple junction disposed downstream of the centerline of the heating structure.

[0065] In another example embodiment, a method for manufacturing a device for sensing fluid flow rate is provided. The method may include providing a heating structure having a centerline. The method may further include disposing at least a portion of a thermoelectric stack on the heating structure. The thermoelectric stack may include a first thermocouple having a first thermocouple junction disposed upstream of the centerline of the heating structure. The thermoelectric stack may further include a second thermocouple having a second thermocouple junction disposed downstream of the centerline of the heating structure.

[0066] In yet another example embodiment, an apparatus for sensing fluid flow rate is provided. The apparatus may include a flow sensing device comprising a heating structure having a centerline. The flow sensing device may further include a first thermopile comprising a first plurality of thermocouples disposed upstream of the centerline of the heating structure. The first plurality of thermocouples may include a first subset of the first plurality of thermocouples aligned generally parallel to the centerline of the heating structure. The first plurality of thermocouples may further include a second subset of the first plurality of thermocouples aligned generally perpendicular to the centerline of the heating structure. The flow sensing device may further include a second thermopile comprising a second plurality of thermocouples disposed downstream of the centerline of the heating structure. The second plurality of thermocouples may include a third subset of the second plurality of thermocouples aligned generally parallel to the centerline of the heating structure. The second plurality of thermocouples may further include a fourth subset of the second plurality of thermocouples aligned generally perpendicular to the centerline of the heating structure.

[0067] In yet another example embodiment, a method for manufacturing a device for sensing fluid flow rate is provided. The method may include providing a heating structure having a centerline. The method may further include disposing a first thermopile upstream of the centerline of the heating structure. The first thermopile may include a first plurality of thermocouples disposed upstream of the centerline of the heating structure. The first plurality of thermocouples may include a first subset of the first plurality of thermocouples aligned generally parallel to the centerline of the heating structure. The first plurality of thermocouples may further include a second subset of the first plurality of thermocouples aligned generally perpendicular to the centerline of the heating structure. The method may further include disposing a second thermopile downstream of the centerline of the heating structure. The second thermopile may include a second plurality of thermocouples disposed downstream of the centerline of the heating structure. The second plurality of thermocouples may include a third subset of the second plurality of thermocouples aligned generally parallel to the centerline of the heating structure. The second plurality of thermocouples may further include a fourth subset of the second plurality of thermocouples aligned generally perpendicular to the centerline of the heating structure.

[0068] In some exemplary embodiments, a flow sensor is provided, comprising: a flow channel configured to deliver fluid therethrough, the flow channel being disposed along a first axis; a heating element disposed near the flow channel, wherein the heating element is configured to release a predetermined amount of heat energy, the center of the heating element being disposed along a second axis at least substantially perpendicular to the first axis; one or more first thermal sensing elements disposed at a first distance from the center of the heating element along the first axis, wherein a change in the voltage difference between the inlet and outlet of the one or more first thermal sensing elements indicates a temperature change at the one or more first thermal sensing elements; and one or more second thermal sensing elements disposed at a second distance from the center of the heating element along the first axis, the second distance being greater than the first distance, wherein a change in the voltage difference between the inlet and outlet of the one or more second thermal sensing elements indicates a temperature change at the one or more second thermal sensing elements, wherein the flow sensor is configured to determine the flow rate of the fluid through the flow channel based on a correlation between the sum of the first and second voltage differences and the flow rate of the fluid through the flow channel.

[0069] In some embodiments, the one or more first thermal sensing elements and the one or more second thermal sensing elements are positioned upstream or downstream of the heating element.

[0070] In some embodiments, the flow sensor may further include circuitry configured to at least: determine a sum of a first voltage difference and a second voltage difference; and compare the sum of the first voltage difference and the second voltage difference with a calibration curve that correlates a plurality of summed voltage differences with the flow rate of the fluid.

[0071] In some embodiments, the one or more first thermal sensing elements or the one or more second thermal sensing elements include at least one of the following: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple, or a thermopile.

[0072] In some embodiments, the one or more first thermal sensing elements are positioned at a first distance from the center of the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel, wherein the one or more second thermal sensing elements are positioned at a second distance from the center of the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel, and wherein the flow sensor further includes: one or more third thermal sensing elements positioned at a first distance from the center of the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel; and one or more fourth thermal sensing elements positioned at a second distance from the center of the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel.

[0073] In some embodiments, the flow sensor may further include a sensor component including a top surface and defining an inner cavity; and a membrane disposed on a portion of the top surface of the sensor component, wherein the one or more first thermal sensing elements and the one or more second thermal sensing elements are disposed on or within the membrane.

[0074] In some embodiments, each of the one or more first thermal sensing elements and the one or more second thermal sensing elements includes a first thermocouple material operatively coupled to a thermocouple contact at a first end, and a second thermocouple material operatively coupled to a thermocouple contact at a first end.

[0075] In some embodiments, the thermocouple contact is positioned at the first distance from the center of the heating element, and wherein the second end of the first thermocouple material and the second end of the second thermocouple material extend beyond the edge of the membrane.

[0076] In some implementations, the flow channel has a height or diameter between about 1 μm and about 500 μm.

[0077] In some implementations, the flow sensor is configured to measure flow rates between about 0.1 mL / h and about 1,000 mL / h.

[0078] In some embodiments, the heating element has a width between about 5 μm and about 100 μm, and the heating element has a length between about 50 μm and about 1,000 μm.

[0079] In some implementations, the one or more first thermal sensing elements are configured to be electrically coupled to the one or more second thermal sensing elements.

[0080] In some implementations, the first distance is between about 25 μm and about 75 μm, and the second distance from the heating element is between about 125 μm and about 175 μm.

[0081] According to another exemplary embodiment, a flow sensor can be provided, comprising: a flow top cover member that at least partially defines a flow channel configured to convey fluid therethrough, the flow channel being substantially disposed along a first axis; a sensor member including a top surface and defining an inner cavity, the flow top cover being operatively coupled to at least a portion of the top surface of the sensor member, the sensor member comprising: a heating element disposed on or within the sensor member, the heating element being disposed along a second axis at least substantially perpendicular to the first axis; a first thermal sensing element disposed on or within the sensor member along the second axis and spaced a first distance from the center of the heating element in a first direction, wherein a first output voltage is measurable at the outlet of the first thermal sensing element; and a second thermal sensing element disposed along the second axis. A second thermal sensing element is disposed on or within the sensor component and spaced a second distance from the center of the heating element in a first direction, the second distance being greater than the first distance, wherein a second output voltage can be measured at the outlet of the second thermal sensing element; a third thermal sensing element is disposed on or within the sensor component along the second axis and spaced a first distance from the center of the heating element in a second direction, the second direction being opposite to the first direction, wherein a third output voltage can be measured at the outlet of the third thermal sensing element; and a fourth thermal sensing element is disposed on or within the sensor component along the second axis and spaced a second distance from the center of the heating element in a second direction, wherein a fourth output voltage can be measured at the outlet of the fourth thermal sensing element, wherein the voltage difference between the sum of the first and second output voltages and the sum of the third and fourth output voltages indicates the flow rate of fluid through the flow channel.

[0082] In some embodiments, one or more of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element include at least one of the following: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple, or a thermopile.

[0083] In some embodiments, at least a portion of each of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element is disposed on or in a membrane disposed on or in the sensor component, wherein each of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element includes a first thermocouple material operatively coupled to a thermocouple contact at a first end, and a second thermocouple material operatively coupled to a thermocouple contact at a first end.

[0084] In some embodiments, the second end of the first thermocouple material is positioned at a first distance from the center of the heating element, wherein the second end of the second thermocouple material is positioned at a second distance from the center of the heating element, wherein the first distance is between about 25 μm and about 75 μm, and wherein the second distance is between about 125 μm and about 175 μm.

[0085] In some embodiments, the membrane comprises one or more first materials, and the sensor assembly comprises one or more second materials, wherein the one or more first materials are substantially thermally insulating and the one or more second materials are substantially thermally conductive.

[0086] According to yet another exemplary embodiment, a method can be performed to measure the flow rate of a fluid in a flow path. In some embodiments, the method may include: causing a heating element to emit a predetermined amount of heat energy, the heating element being positioned substantially perpendicular to the flow path; providing a first current having a first voltage to an inlet of a first thermal sensing element, the first thermal sensing element being spaced apart from the central longitudinal axis of the heating element by a first distance; providing a second current having a second voltage to an inlet of a second thermal sensing element, the second thermal sensing element being spaced apart from the central longitudinal axis of the heating element by a second distance, the second distance being greater than the first distance; measuring the outlet voltage at the respective outlets of the first and second thermal sensing elements; and determining the flow rate of the fluid in the flow path based on the outlet voltages, wherein the outlet voltages at the respective outlets of the first and second thermal sensing elements indicate the flow rate.

[0087] According to yet another exemplary embodiment, a method is executable to manufacture an exemplary flow sensor device. In some embodiments, the method may include providing a flow top cover member that partially defines a flow path oriented along a first axis; providing a sensor member including a heating element oriented substantially along a second axis substantially orthogonal to the first axis, the sensor member further including a first thermal sensing element and a second thermal sensing element, the first thermal sensing element being disposed at a first distance from the heating element along the first axis and the second thermal sensing element being disposed at a second distance from the heating element along the first axis; and bonding the flow top cover member to a first surface of the sensor member to form a flow channel therebetween.

[0088] The above-described exemplary invention, as well as other exemplary objects and / or advantages of this disclosure and the ways in which these objects and / or advantages can be achieved, can be further explained in the following detailed description and accompanying drawings. Attached Figure Description

[0089] The description of the illustrative examples can be read in conjunction with the accompanying drawings. It should be understood that, for the sake of simplicity and clarity of illustration, the parts and elements shown in the figures are not necessarily drawn to scale unless otherwise stated. For example, unless otherwise stated, the dimensions of some parts or elements may be exaggerated relative to others. Examples incorporating the teachings of this disclosure are shown and described with reference to the accompanying drawings given herein, wherein:

[0090] Figure 1A A cross-sectional view of an exemplary flow sensing device according to an example of this disclosure is shown;

[0091] Figure 1B A cross-sectional view of an exemplary flow sensing device according to an example of this disclosure is shown;

[0092] Figure 1C A cross-sectional view of an exemplary flow sensing device according to an example of this disclosure is shown;

[0093] Figure 1D A cross-sectional view of an exemplary flow sensing device according to an example of this disclosure is shown;

[0094] Figure 1E A top view of at least a portion of an exemplary flow sensing device according to the present disclosure is shown;

[0095] Figure 2 A cross-sectional view of at least a portion of an exemplary flow sensing device according to the present disclosure is shown, taken from an angle of 90 degrees rotation of the flow sensing device about axis A-A'. This cross-sectional view is at least similar to... Figure 1A A cross-sectional view of a flow sensing device;

[0096] Figure 3 It is a velocity profile of flow entering a flow channel with a height of approximately 25 μm through a large port, according to an example of this disclosure, the flow channel defining a flow path adjacent to two or more sensing elements;

[0097] Figure 4 It is based on the example of this disclosure. Figure 3 The simulation of the flow-temperature difference for the flow path shown is between approximately 0.125 mL / hr and approximately 2 mL / hr, where the center of the heating element is located approximately at x = 0;

[0098] Figure 5 It is a velocity profile of flow entering a flow channel with a height of approximately 89 μm through a large port, according to an example of this disclosure, the flow channel defining a flow path adjacent to two or more sensing elements;

[0099] Figure 6 It is based on the example of this disclosure. Figure 5 The simulation of the flow-temperature difference for the flow path shown is between approximately 0.1 mL / hr and approximately 20 mL / hr, where the center of the heating element is located approximately at x = 0;

[0100] Figure 7 It is a velocity profile of flow entering a flow channel with a height of approximately 349 μm through a large port, according to an example of this disclosure, the flow channel defining a flow path adjacent to two or more sensing elements;

[0101] Figure 8 It is based on the example of this disclosure. Figure 7 The simulation of the flow rate temperature difference for the flow path shown is between approximately 10 mL / hr and approximately 1,000 mL / hr, where the center of the heating element is located approximately at x = 0;

[0102] Figure 9A According to an example of this disclosure, for a flow sensor device having two sensing elements positioned at different distances from a heater element, the temperature difference between the outer and inner sides of the membrane is graphically represented as a function of the flow rate of a medium such as a fluid passing through a nearby flow channel.

[0103] Figure 9B According to an example of this disclosure, for a flow sensor device having three sensing elements positioned at different distances from the heater element, the temperature difference between the outer and inner sides of the membrane is graphically represented as a function of the flow rate of a medium such as a fluid passing through a nearby flow channel.

[0104] Figure 10 This is a top view schematic diagram of a flow device according to an example of this disclosure;

[0105] Figure 11 This is a top view schematic diagram of a flow device including two upstream thermal sensing elements and two downstream thermal sensing elements according to an example of this disclosure;

[0106] Figure 12 This is a top view schematic diagram of a flow device including two upstream thermal sensing elements and two downstream thermal sensing elements according to an example of this disclosure;

[0107] Figure 13 This is a top view schematic diagram of a flow device including two downstream thermal sensing elements according to an example of this disclosure;

[0108] Figure 14 This is a top view schematic diagram of a flow device including two downstream thermal sensing elements according to an example of this disclosure;

[0109] Figure 15 An exemplary perspective top view of at least a portion of an exemplary flow sensing device according to an example of this disclosure is shown;

[0110] Figure 16 An exemplary perspective top view of at least a portion of an exemplary flow sensing device according to an example of this disclosure is shown;

[0111] Figure 17 An exemplary configuration of a heating element according to an example of this disclosure is shown;

[0112] Figure 18 It is a graphical representation of liquid flow rate at various temperatures and distances from the thermal sensor of the heating element, according to an example of this disclosure;

[0113] Figure 19A This is an example of an exemplary flow sensor according to the present disclosure, having two sensing elements positioned at different distances from the heating element, in which the temperature difference between the outer and inner sides of the membrane is represented as a graphical representation of the flow rate of a medium such as fluid flowing through a nearby flow channel.

[0114] Figure 19B The temperature difference between the outer and inner sides of the membrane is a graphical representation of the flow rate of a medium, such as fluid flowing through a nearby flow channel, for an exemplary flow sensor having three sensing elements positioned at different distances from the heating element, according to an example of this disclosure.

[0115] Figure 20 An exemplary configuration of a heating element according to an example of this disclosure is shown;

[0116] Figure 21 It is a graphical representation of liquid flow rate at various temperatures and distances from the thermal sensor of the heating element, according to an example of this disclosure;

[0117] Figure 22AThis is an example of an exemplary flow sensor according to the present disclosure, having two sensing elements positioned at different distances from the heating element, in which the temperature difference between the outer and inner sides of the membrane is represented as a graphical representation of the flow rate of a medium such as fluid flowing through a nearby flow channel.

[0118] Figure 22B The temperature difference between the outer and inner sides of the membrane is a graphical representation of the flow rate of a medium, such as fluid flowing through a nearby flow channel, for an exemplary flow sensor having three sensing elements positioned at different distances from the heating element, according to an example of this disclosure.

[0119] Figure 23 An exemplary configuration of a heating element according to an example of this disclosure is shown;

[0120] Figure 24 This is a graphical representation of the temperature difference at various distances from the heater element as a function of the flow rate of a medium such as fluid flowing through a nearby flow channel, according to an example of this disclosure for an exemplary flow sensor.

[0121] Figure 25A According to an example of this disclosure, for an exemplary flow sensor having two sensing elements positioned at different distances from a heating element, the temperature difference between the outer and inner sides of the membrane is graphically represented as a function of the flow rate of a medium such as fluid flowing through a nearby flow channel; and

[0122] Figure 25B This is an example of an exemplary flow sensor according to the present disclosure, having three sensing elements positioned at different distances from the heating element, wherein the temperature difference between the outer and inner sides of the membrane is a graphical representation as a function of the flow rate of a medium such as fluid flowing through a nearby flow channel. Detailed Implementation

[0123] Examples of this disclosure will be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, examples of this disclosure. In fact, these disclosures may be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided to enable this disclosure to meet applicable legal requirements. Throughout this document, similar reference numerals refer to similar elements.

[0124] The phrases “in one example,” “according to one example,” “in some examples,” etc., generally refer to a particular feature, structure, or characteristic that follows the phrase and may include at least one example of this disclosure, and may include more than one example of this disclosure (importantly, such phrases do not necessarily refer to the same example).

[0125] If the specification states that a component or feature “may,” “can,” “should,” “will,” “preferably,” “possibly,” “usually,” “optionally,” “for example,” “as an example,” “in some examples,” “often,” or “may” (or other such language) be included or have that characteristic, then the specific component or feature is not necessarily required to include or have that characteristic. Such components or features may be optionally included in some examples or excluded.

[0126] The terms “example” or “exemplary” as used herein mean “serving as an example, instance, or illustration.” Any specific implementation described herein as an “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other specific implementations.

[0127] In this disclosure, the terms “electrical coupling,” “communication with,” “electronic communication with,” or “connection” refer to two or more elements or components connected by wired and / or wireless means such that signals, voltages / currents, data, and / or information can be transmitted to and / or received from these elements or components.

[0128] In this disclosure, the term "flow sensing device" refers to a device capable of detecting, measuring, and / or identifying the flow rate (including, but not limited to, linear velocity, nonlinear velocity, mass flow rate, and / or volumetric flow rate) of one or more flowing media. In this disclosure, the term "flowing medium" refers to a substance (such as, but not limited to, liquid substances and / or gaseous substances).

[0129] For example, exemplary flow sensing devices may be implemented in invasive or non-invasive drug delivery systems to detect, measure, and / or identify the flow rate of a fluid medium associated with the invasive or non-invasive drug delivery system. In such examples, an infusion pump may be implemented to deliver substances (such as, but not limited to, fluids, drugs, and / or nutrients) into a patient within an invasive drug delivery system. It may be necessary to deliver the substance in a controlled manner. Therefore, exemplary flow sensing devices may be implemented in an infusion pump to detect, measure, and / or identify the flow rate of a substance that can be delivered to the patient.

[0130] In various examples, it may be necessary to accurately measure the flow rate of the fluid. Continuing with the infusion pump example above, depending on the patient's condition and / or the treatment being administered, it may be necessary to deliver the substance at a low flow rate. For example, the substance may need to be delivered at a rate of less than 5 ml / hour. If the flow rate is not accurately measured, the patient may be over- or under-administered medication, which can lead to injury, harm, and / or death. For example, in 2019, at least 21 patients died in the United States, and these deaths are known to be at least in part caused by over-infusion of medication in invasive drug delivery systems, resulting in costs of at least seven million dollars.

[0131] To address the challenges and limitations associated with measuring flow rate, various examples of this disclosure are provided. For example, various examples of this disclosure provide exemplary flow sensing devices and exemplary manufacturing methods for providing exemplary flow sensing devices.

[0132] In some examples, exemplary flow sensing devices include a heating element disposed on the side of a thermal sensing element opposite to the flow channel. In such examples, the thermal sensing element may be directly heated by the heating element, and the flow medium in the flow channel may act as a heat sink on the opposite side of the thermal sensing element.

[0133] In some examples, exemplary flow sensing devices may separate the heating element from the thermal sensing element. For example, the heating element and the thermal sensing element may be located on opposite sides of the flow channel. In such examples, the thermal sensing element may not be heated to the elevated temperature of the heating element, but rather directly heated by the flow medium.

[0134] Alternatively, one or more plate elements (such as temperature uniformity plates) may be provided such that the one or more plate elements at least partially overlap with the thermal sensing element to, for example, but not limited to, improve the output signal and sensitivity.

[0135] Therefore, some examples of this disclosure may, for example but not limited to, improve the performance, sensitivity, accuracy and / or drift of flow sensing devices, and / or enable the measurement of flow in infusion pumps of invasive drug delivery systems.

[0136] Now for reference Figures 1A to 1E An exemplary view of at least a portion of an exemplary flow sensing device 100 is shown.

[0137] Specifically, Figures 1A to 1D An exemplary cross-sectional view of at least a portion of an exemplary flow sensing device 100 according to various embodiments of the present disclosure is shown. Figure 1E An exemplary top view of at least a portion of an exemplary flow sensing device 100 is shown. For example, Figure 1A and Figure 1D An exemplary sectional view can be taken from a plane defined by axis C-C'.

[0138] Figures 1A to 1D Various examples of a flow sensing device 100 are shown, which may include a flow top cover component 101 and a sensor component 103.

[0139] In this disclosure, the term "component" refers to an article of writing, apparatus, or device that may include one or more surfaces, portions, layers, and / or elements. For example, an exemplary component may include one or more substrates that may provide one or more underlying layers for the component, and may include one or more elements that may be disposed within and / or on top of the substrate. In this disclosure, the term "element" refers to an article of writing, apparatus, or device that may provide one or more functions.

[0140] For example, the flow top cover component 101 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics. Alternatively, the sensor component 103 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics.

[0141] In some embodiments, the flow top cover component 101 may include one or more heating elements, such as, but not limited to, heating element 105.

[0142] In this disclosure, the term "heating element" refers to an article, apparatus, or device that can impart heat, increase its temperature, and / or raise the temperature of the environment surrounding and / or adjacent to the heating element. For example, heating element 105 may include a coil, a strip (including but not limited to a straight strip, a corrugated strip), a plate, a connecting strip, and / or a layer connectable to a power source. In some examples, the heating element may include various geometries, including but not limited to zigzag, zigzag with rounded corners, S-shaped, S-shaped with rounded corners, double helix, double helix with rounded corners, double helix with irregular spacing, a plate with a central square hole, circular, drive wheel-shaped, elliptical, honeycomb, or irregular shapes. When the power source is turned on, current can flow through the coil, strip, plate, connecting strip, and / or layer, which in turn converts electrical energy into heat energy.

[0143] In some examples, heating element 105 may comprise nickel-based and / or iron-based materials. For example, heating element 105 may comprise one or more materials, such as a nickel-iron (NiFe) alloy, which provides a high temperature coefficient of resistance. For example, heating element 105 may comprise 81% nickel (Ni) and 19% iron (Fe). Alternatively, heating element 105 may comprise 60% Ni and 40% Fe.

[0144] In some examples, heating element 105 may comprise platinum, such as platinum in the form of a thin-film heater due to its high temperature coefficient of resistance (TCR). In some examples, copper alloys with low thermal conductivity, such as Alloy 52, may also be used for heating element 105.

[0145] While the above description provides some examples of heating elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, exemplary heating elements may include one or more additional and / or alternative elements, one or more additional and / or alternative materials, and / or may be in other forms. For example, exemplary heating elements may comprise materials such as, but not limited to, polycrystalline silicon, platinum (Pt), Ni, nickel-chromium alloy (NiCr), and CrSi2. In addition or alternatively, exemplary heating elements may include metals such as, but not limited to, Au, Pd, Mo, Ti, W, Hf, Zr, Cr, and their silicides and combinations thereof. In addition or alternatively, exemplary materials for exemplary heating elements may be selected from those materials having a temperature coefficient of resistance ranging from near zero to positive.

[0146] While the above description provides an exemplary flow top cover component including two heating elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary flow top cover component may include fewer or more than two heating elements.

[0147] exist Figure 1A In the example shown, the heating element 105 may be disposed in the first layer 109 of the flow top cover component 101. Figure 1B In the example shown, thermal sensing elements 111 and 113 may be disposed in the first layer 109 of the sensor component 103, and heating element 105 may be disposed in the second layer 115 of the sensor component 103. Figure 1C In the example shown, the heating element 105 may be disposed in the first layer 109 of the sensor component 103, and the thermal sensing elements 111, 113 may be disposed in the second layer 115 of the sensor component 103.

[0148] Although Figure 1A The example shown illustrates a single heating element, but it should be noted that examples of this disclosure may include two or more heating elements.

[0149] Furthermore, in various examples of this disclosure, the flow top cover component 101 may be an integral part of the exemplary flow sensing device 100. For example, the exemplary flow sensing device 100 may be etched to form a flow channel (as further described herein), and the flow top cover component 101 may refer to the portion of the exemplary flow sensing device 100 above the flow channel.

[0150] In some examples, the first layer 109 of the flow top cover component 101 may comprise a material such as, but not limited to, silicon nitride (Si3N4). For example, the first layer 109 may be an encapsulation layer. In some examples, the encapsulation layer may comprise other materials, including but not limited to silicon nitride, silicon oxide, silicon oxynitride, polymers, or other electrically insulating films.

[0151] In some examples, such as Figure 1D As shown, heater element 105 and thermal sensing elements 111, 113 may be disposed in the same layer (e.g., 109) of flow top cover component 101, or may be disposed in the same layer of sensor component 103.

[0152] Alternatively or in addition, the flow top cover component 101 and the sensor component 103 may contain materials that have a similar coefficient of thermal expansion (TCE).

[0153] In some examples, heating element 105 may be electrically coupled to one or more other components (e.g., a power source) based on techniques such as, but not limited to, through-glass vias (TGV), through-silicon vias (TSV), and / or aerosol or inkjet printing. As described herein, one or more “vias” may comprise electrical connections between layers in a physical electronic circuit. In addition or alternatively, heating element 105 may be electrically coupled to one or more other components via other means.

[0154] refer to Figure 1A The sensor component 103 may include one or more thermal sensing elements, such as, but not limited to, a first thermal sensing element 111 and a second thermal sensing element 113.

[0155] In this disclosure, the term "thermal sensing element" refers to an article, apparatus, or device capable of detecting, measuring, and / or identifying the thermal level (e.g., temperature) of the environment surrounding and / or adjacent to the thermal sensing element. For example, a first thermal sensing element 111 and / or a second thermal sensing element 113 may include one or more thermopile elements. In such examples, exemplary thermopile elements may include one or more thermocouples connected in series or parallel, which may detect, measure, and / or identify thermal energy and may convert the thermal energy into electrical energy and / or generate one or more electrical signals based on the detected / measured / identified thermal energy.

[0156] While the above description provides some examples of thermal sensing elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, exemplary thermal sensing elements may include one or more additional and / or alternative elements, one or more additional and / or alternative materials, and / or may be in other forms. For example, exemplary thermal sensing elements may include at least one temperature sensing circuit, such as, but not limited to, a resistor or a thermistor in a Wheatstone bridge circuit.

[0157] In an example of a Wheatstone bridge circuit, two resistor branches may be provided, and each resistor branch may include two resistor elements. Since temperature can affect the resistance of the resistor elements, an exemplary thermal sensing element can detect, measure, and / or identify the resistance change between the two resistor branches to determine the corresponding thermal energy.

[0158] While the above description provides exemplary sensor components including two thermal sensing elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary sensor components may include fewer or more than two thermal sensing elements.

[0159] exist Figure 1A In the example shown, the first thermal sensing element 111 and the second thermal sensing element 113 may be disposed in the second layer 115 of the sensor component 103. In some examples, the second layer 115 of the sensor component 103 may contain materials such as, but not limited to, silicon nitride (Si3N4). In addition or alternatively, the second layer 115 of the sensor component 103 may include other materials, including but not limited to silicon nitride, silicon oxide, silicon oxynitride, polymers, or other electrically insulating films.

[0160] In some examples, the second layer 115 may be an encapsulation layer that protects the thermal sensing element, and this encapsulation layer may contain a metal that can be corroded by moisture and other chemicals. In some examples, the second layer 115 may be electrically insulating.

[0161] In some examples, the first thermal sensing element 111 and / or the second thermal sensing element 113 may be electrically coupled to one or more other components (e.g., power supply, processor) based on techniques such as, but not limited to, through-glass via (TGV), through-silicon via (TSV), and / or aerosol or inkjet printing. Alternatively or otherwise, the first thermal sensing element 111 and / or the second thermal sensing element 113 may be electrically coupled to one or more other components via other means.

[0162] In some examples, the first layer 109 of the flow top cover component 101 and the second layer 115 of the sensor component 103 may be non-coplanar. In other words, the first layer 109 of the flow top cover component 101 may not occupy the same plane as the second layer 115 of the sensor component 103.

[0163] As described above, the first layer 109 of the flow top cover component 101 may include a heating element disposed therein, and the second layer 115 of the sensor component 103 may include at least one thermal sensing element disposed therein. Since the first layer 109 of the flow top cover component 101 and the second layer 115 of the sensor component 103 may be non-coplanar, the heating element may also be non-coplanar with the at least one thermal sensing element. Figure 1A In the example shown, heating element 105 may be coplanar and occupy a first plane, and first thermal sensing element 111 and second thermal sensing element 113 may be coplanar and occupy a second plane. The first plane may be parallel to the second plane.

[0164] Therefore, various examples of this disclosure can separate the heating element 105 from the first thermal sensing element 111 and / or the second thermal sensing element 113. Thus, the first thermal sensing element 111 and / or the second thermal sensing element 113 may not be heated to the elevated temperature of the heating element 105 and can be directly heated by the flow medium received by the flow sensing device 100 (details of which are described herein).

[0165] Re-reference Figure 1A In some examples, the flow top cover component 101 may be bonded to a first surface of the sensor component 103 to form a flow channel. For example, the flow top cover component 101 may be bonded to the first surface of the sensor component 103 via an adhesive material. In addition or alternatively, other bonding mechanisms may be used to bond the flow top cover component 101 to the sensor component 103, including but not limited to oxide glass sealing, anodic bonding, thermoelectric bonding, fusion bonding, metal brazing, direct bonding, etc.

[0166] In some examples, the flow top cover component 101 may include a flow channel portion 117 on a second surface of the flow top cover component 101. Figure 1A In the example shown, the surface of the flow channel portion 117 may be recessed from the surrounding surface of the flow top cover component 101. As described above, the flow top cover component 101 may be bonded to the first surface of the sensor component 103. In some examples, the flow channel portion 117 of the flow top cover component 101 and the first surface of the sensor component 103 may form at least a first portion of the flow channel.

[0167] In this disclosure, the term "flow channel" refers to a pathway through which a flowing medium can travel. In some examples, a flow channel may be a void formed within the flow top cover component 101 and an area on the sensor component 103 defined by the void in the flow top cover component 101 (when these are placed in close contact). As will be described in further detail herein, exemplary flow channels of this disclosure may be defined / formed by and / or include multiple sidewalls.

[0168] In some examples, the first layer 109 of the flow top cover component 101 and the second layer 115 of the sensor component 103 may be separated by flow channels. Thus, various examples of this disclosure may separate the heating element 105 from the first thermal sensing element 111 and / or the second thermal sensing element 113, and the first thermal sensing element 111 and / or the second thermal sensing element 113 may not be heated to the elevated temperature of the heating element 105.

[0169] In some embodiments, the flow top cover component 101 may include a first opening 119 and a second opening 121. In some examples, the first opening 119 and the second opening 121 may be connected to a flow channel portion 117 on a second surface of the flow top cover component.

[0170] In some examples, the flow top cover component 101 may be configured to receive the flow medium through a first opening 119. In some examples, the flow medium may travel through a flow channel and exit the flow top cover component 101 through a second opening 121.

[0171] In some examples, the flowing medium can travel through a sensing region 123, which may include a heating element 105, a first thermal sensing element 111, and a second thermal sensing element 113. For example, the first thermal sensing element 111 may be positioned upstream of the heating element 105. The second thermal sensing element 113 may be positioned downstream of the heating element. In such examples, the first thermal sensing element 111 can detect a first temperature of the flowing medium. The flowing medium can then be heated by the heating element 105, which can raise the temperature of the flowing medium by a predetermined amount. Subsequently, the second thermal sensing element 113 can detect a second temperature of the flowing medium. As the flow rate of the flowing medium increases, more heat can be lost as the flowing medium travels from the heating element 105 to the second thermal sensing element 113. The flow rate of the flowing medium can be calculated by comparing the difference between the first and second temperatures with a predetermined amount.

[0172] Now for reference Figure 1B An exemplary side view of at least a portion of an exemplary flow sensing device 100 is shown. In some examples, Figure 1B Many of the components, structures, configurations, and functions of the flow sensing device 100 shown may be similar to or substantially similar to those described above. Figure 1A The flow sensing devices shown are those described above; however, the heating element 105 may be disposed on or within the sensor component 103 instead of the flow top cover component 101. Therefore, Figure 1B The flow sensing device 100 shown may include the above-mentioned reference. Figure 1A For the sake of brevity, the aforementioned components or parts will not be referred to again. Figure 1B This will be described. Those skilled in the art will understand that many configurations and locations of the heating element 105 are possible while still allowing the flow sensor device 100 to operate as described herein. For example, as... Figure 1B As shown, thermal sensing elements 111 and 113 can be disposed in the first layer 109 of the sensor component 103, while heating element 105 can be disposed in the second layer 115 of the sensor component 103 opposite to the first layer 109 in the flow channel 119.

[0173] Now for reference Figure 1C An exemplary side view of at least a portion of an exemplary flow sensing device 100 is shown. In some examples, Figure 1CMany of the components, structures, configurations, and functions of the flow sensing device 100 shown may be similar to or substantially similar to those described above. Figure 1A The flow sensing devices shown are those described above; however, the heating element 105 may be disposed on or within the sensor component 103 instead of the flow top cover component 101. Therefore, Figure 1C The flow sensing device 100 shown may include the above-mentioned reference. Figure 1A For the sake of brevity, the aforementioned components or parts will not be referred to again. Figure 1C This will be described. Those skilled in the art will understand that many configurations and locations of the heating element 105 are possible while still allowing the flow sensor device 100 to operate as described herein. For example, as... Figure 1C As shown, thermal sensing elements 111 and 113 can be disposed in the second layer 115 of the sensor component 103, while heating element 105 can be disposed in the first layer 109 of the sensor component 103, with the second layer 115 opposite to the first layer 109 in the flow channel 119.

[0174] Now for reference Figure 1D An exemplary side view of at least a portion of an exemplary flow sensing device 100 is shown. In some examples, Figure 1D Many of the components, structures, configurations, and functions of the flow sensing device 100 shown may be similar to or substantially similar to those described above. Figure 1A The flow sensing devices shown are those described above; however, the heating element 105 may be disposed on or within the sensor component 103 instead of the flow top cover component 101. Therefore, Figure 1D The flow sensing device 100 shown may include the above-mentioned reference. Figure 1A For the sake of brevity, the aforementioned components or parts will not be referred to again. Figure 1D This will be described. Those skilled in the art will understand that many configurations and locations of the heating element 105 are possible while still allowing the flow sensor device 100 to operate as described herein. For example, as... Figure 1D As shown, thermal sensing elements 111, 113 and heating element 105 may be disposed in the same layer (e.g., 109) such that heating element 105 and thermal sensing elements 111, 113 are coplanar or substantially coplanar.

[0175] Now for reference Figure 1EAn exemplary top view of at least a portion of an exemplary flow sensor device 100 is shown. This top view of at least a portion of the exemplary flow sensor device 100 provides a clearer illustration of a possible location of a thermal sensor element within the flow sensor device 100. In some examples, a flow top cover member 101 may engage with a sensor member 103 to form the flow sensor device 100. In some examples, the flow top cover member 101 may define a flow channel 125. In other examples, the flow channel 125 may be defined partially by the flow top cover member 101 and partially by the sensor member 103, such that when the flow top cover member 101 is engaged, coupled, adhered to, or otherwise disposed to the top surface of the sensor member 103, the flow channel 125 is at least partially defined therebetween.

[0176] In some examples, the sensing region 123 may be defined or disposed along, adjacent to, above, below, or otherwise near the flow channel 125. In some examples, the sensing region 123 may include a first thermal sensor element (not shown) and a second thermal sensor element (not shown). The first thermal sensor element and the second thermal sensor element may be referred to herein as "thermal sensing elements".

[0177] In some examples, the sensing region 123 may also include a heating element (not shown) configured to at least heat the flow channel and the medium therein. In some examples, the heating element may be disposed on or within one or more of the flow top cover component 101 or the sensor component 103. In some examples, the heating element may be rectangular, cylindrical, generally planar, or otherwise sized. In some embodiments, the length of the heating element may be greater than the width of the heating element, for example, approximately twice, three times, four times, etc. In some examples, the sensing region 123 may be positioned such that the heating element is at least partially disposed above or below the flow channel 125. In some embodiments, the heating element may be oriented in the sensing region 123 such that the length of the heating element is substantially perpendicular to the flow direction of the medium within the flow channel 125.

[0178] In some implementations, the centerline of the heating element (e.g., Figures 1A to 1D The A-A' in the diagram can be used to define the end position of the upstream portion of the flow channel 125 and the beginning position of the downstream portion of the flow channel 125.

[0179] In some embodiments, the thermal sensing element may be disposed on or within the flow top cover component 101, or on or within the sensor component 103. In some examples, the thermal sensing element may be disposed above, below, adjacent to, or otherwise near the flow channel 125 and the heating element. In some examples, the thermal sensing element may be positioned at one or more predetermined distances from the heating element along its length. In some examples, a first thermal sensing element may be positioned at a first distance from the heating element, and a second thermal sensing element may be positioned at a second distance from the heating element, the second distance being greater than the first distance.

[0180] In some examples, the thermal sensing element may include a first end having a current input and a second end having a current output. In some embodiments, the thermal sensing element may include one or more materials configured to influence one or more characteristics of the current transmitted through it based on the temperature of the one or more materials. In other words, the thermal sensing element may be at least partially heated by a heating element such that the temperature of the one or more materials changes with the amount of heat conducted between the heating element and the thermal sensing element. The one or more characteristics of the current may include voltage, etc. In some examples, the one or more materials may be selected such that the voltage of the current at the output of the thermal sensing element indicates the temperature of the one or more materials.

[0181] In some examples, the thermal sensing element may be calibrated to one or more predetermined or known temperatures, one or more predetermined or known input currents of the heating element, one or more predetermined or known characteristics (e.g., voltage) of the input currents of the thermal sensing element, and / or one or more predetermined or known flow rates through the flow channel 125. In some examples, a first known and constant flow rate of the medium through the flow channel 125 is maintained, a first current with a known voltage is applied to the input of the heating element, a second current with a known voltage is applied to the input of the first thermal sensing element, a third current with a known voltage is applied to the input of the second thermal sensing element, and the voltages of the output currents from the first and second thermal sensing elements are measured to determine the corresponding voltages; then, the flow rate of the medium through the flow channel 125 is increased or decreased from the first known and constant flow rate to achieve a second known and constant flow rate, the same current previously applied at the first known and constant flow rate is applied to the inputs of the heating element and the thermal sensing element, and the output voltage of the thermal sensing element is measured again. This type of method can be used for a variety of different known and constant flow rates to create a calibration curve of the output voltage from the thermal sensing element to the flow rate of the medium through the flow channel 125.

[0182] Other methods can be used to calibrate the thermal sensing element such that the voltage or other characteristic of the output current from the thermal sensing element predictably indicates temperature changes at the thermal sensing element, and many such calibration methods will be apparent to those skilled in the art with reference to this disclosure. In some examples, the thermal sensing element can be calibrated before assembling the flow sensor device 100, after assembling the flow sensor device 100 but before integrating it into a delivery pumping system, or after integrating the flow sensor device 100 into a delivery pumping system, etc.

[0183] In some examples, the sensing region 123 may include a film or sensing layer comprising a relatively thermally conductive material, while the surrounding portion of the sensing region 123 and / or the surrounding portion of the flow top cover member 101 or the sensor member 103 comprises a relatively thermally insulating material. In some embodiments, a thermal sensing element may be disposed within or partially disposed therein of the film or sensing layer of the sensing region 123. In some examples, the thermal sensing element may be disposed only partially within the sensing region 123. In other words, in some examples, a first portion of the thermal sensing element may be disposed within the film or sensing layer, and a second portion of the thermal sensing element may extend beyond the outer edge of the film or sensing layer and enter into the surrounding portion of the sensing region 123 or the surrounding portion of the flow top cover member 101 or the sensor member 103. Without being bound by any particular theory, the thermal sensing element can output a current having a voltage reflecting the temperature difference between the interior and exterior of the sensing area 123 by extending from the thermally conductive area of ​​the sensing area 123 to the thermally insulating area of ​​the sensing area 123 or to one of 101 or 103. This can help distinguish the contribution of the thermal sensing element to the measured temperature from changes in ambient / environmental conditions from the contribution of the thermal sensing element to the measured temperature from the effective heating of the thermal sensing element by the heating element, which is directly affected by the flow rate of the medium (which acts as a heat sink) through the flow channel 125.

[0184] In some examples, the distance between the thermal sensing element and the heating element can be selected to achieve acceptable flow measurement accuracy over an acceptable wide flow range and / or a desired flow range (e.g., low flow rates between about 1 μL / h and about 1,000 μL / h). In some embodiments, the number of thermal sensing elements can also be selected to achieve flow measurement accuracy over a desired flow range. In some examples, using only a single thermal sensing element may result in a tailing of accuracy or precision at certain flow rates (such as low flow rates). In some examples, using two thermal sensing elements spaced at different distances from the heating element may result in improved accuracy at low flow rates, etc. It is not desirable to be bound by any particular theory; the increased accuracy or precision at low flow rates, etc., may be due to the difference in peak accuracy between the closer thermal sensing element and the more distant thermal sensing element. In some examples, closer thermal sensing elements are better suited for accurately and / or precisely measuring higher flow rates because higher flow rates of the medium increase the heat sink capacity of the medium in flow channel 125. In some examples, more distant thermal sensing elements are better suited for accurate and / or precise measurement of lower flow rates because lower flow rates reduce the heat dissipation capacity of the medium, and temperature differences can be more easily detected by thermal sensing elements located further away.

[0185] In some examples, when the thermal sensing element comprises a thermopile consisting of multiple thermocouples, using more thermocouples within the thermopile can be beneficial, as it increases the thermopile's sensitivity to temperature changes, which in turn increases the sensitivity of the flow sensor. In some examples, such as for digital sensors, this can improve the accuracy of the multiple bits representing the measured voltage value.

[0186] In some examples, the flow top cover component 101 may be bonded to a first surface of the sensor component 103 to form a flow channel. For example, the flow top cover component 101 may be bonded to the first surface of the sensor component 103 via an adhesive material at one or more bonding pads 127, etc. In addition to or alternatively, other bonding mechanisms may be used to bond the flow top cover component 101 to the sensor component 103, including but not limited to oxide glass sealing, anodic bonding, thermoelectric bonding, fusion bonding, metal brazing, direct bonding, etc.

[0187] In some examples, the flow top cover component 101 may include a flow channel portion (not shown) on a second surface of the flow top cover component 101. In some examples, the surface of the flow channel portion may be recessed from a surrounding surface of the flow top cover component 101. As described above, the flow top cover component 101 may be bonded to a first surface of the sensor component 103. In some examples, the flow channel portion of the flow top cover component 101 and the first surface of the sensor component 103 may form at least a first portion of the flow channel.

[0188] In some examples, the flow channel may be a void formed within the flow top cover component 101 and an area on the sensor component 103 defined by the void in the flow top cover component 101 (when these are placed in close contact). As will be described in further detail herein, exemplary flow channels of this disclosure may be defined / formed by and / or include multiple sidewalls.

[0189] In some examples, the first layer of the flow top cover component 101 and the second layer of the sensor component 103 may be separated by a flow channel. Therefore, various examples of this disclosure may separate the heating element (not shown) from the first thermal sensing element (not shown) and / or the second thermal sensing element (not shown), and the first thermal sensing element and / or the second thermal sensing element may not be heated to the elevated temperature of the heating element.

[0190] In some embodiments, the flow top cover component 101 may include a first opening 119 and a second opening 121. In some examples, the first opening 119 and the second opening 121 may be connected to a flow channel portion on a second surface of the flow top cover component 101.

[0191] In some examples, the flow top cover component 101 may be configured to receive the flow medium through a first opening 119. In some examples, the flow medium may travel through a flow channel 125 and exit the flow top cover component 101 through a second opening 121.

[0192] In some examples, the flowing medium can travel through a sensing region 123, which may include a heating element, a first thermal sensing element, and a second thermal sensing element. For example, the first thermal sensing element may be positioned upstream of the heating element, and the second thermal sensing element may be positioned downstream of the heating element. In some examples, both the first and second thermal sensing elements may be positioned upstream or downstream of the heating element. In some examples, the flow sensor device 100 may also include a third and a fourth thermal sensing element. In some examples, the first and second thermal sensing elements may be positioned upstream of the heating element, while the third and fourth thermal sensing elements may be positioned downstream of the heating element. In some examples, the first and third thermal sensing elements may be positioned at a first distance from the heating element, while the second and fourth thermal sensing elements may be positioned at a second distance from the heating element. In some examples, the first distance from the heating element may be less than the second distance from the heating element. In some examples, a first thermal sensing element may be positioned at a first distance from the heating element, a second thermal sensing element may be positioned at a second distance from the heating element, a third thermal sensing element may be positioned at a third distance from the heating element, and a fourth thermal sensing element may be positioned at a fourth distance from the heating element, wherein the first, second, third, and fourth distances may each be different from each other. The second thermal sensing element may be positioned in the downstream direction of the heating. In some examples, the first thermal sensing element may detect a first temperature of the heating element, the second thermal sensing element may detect a second temperature of the heating element, the third thermal sensing element may detect a first temperature of the flowing medium, and the fourth thermal sensing element may detect a second temperature of the flowing medium. In some examples, the first thermal sensing element may detect a first temperature of the flowing medium, the second thermal sensing element may detect a second temperature of the flowing medium, the third thermal sensing element may detect a third temperature of the flowing medium, and the fourth thermal sensing element may detect a fourth temperature of the flowing medium.

[0193] In some examples, the heating element can be deactivated or not activated, and a first temperature of the flowing medium can be measured by one or more of the thermal sensing elements. Subsequently, the heating element can be activated, and the flowing medium can be heated by the heating element, either by increasing the temperature of the flowing medium by a predetermined amount or by changing the current flowing to the heating element. A second temperature of the flowing medium can then be detected by one or more of the thermal sensing elements. As the flow rate of the flowing medium increases, more heat can be lost as the flowing medium travels from the heating element to the second thermal sensing element. The flow rate of the flowing medium can be calculated by comparing the difference between the first and second temperatures.

[0194] exist Figure 1EIn the example shown, a flow top cover component 101 may be disposed on a first surface of a sensor component 103. As described above, a first opening 119 of the flow top cover component 101 may receive an exemplary flow medium from the flow sensing device 100. The flow medium may travel through a flow channel 125 (including a sensing region 123) and exit the flow sensing device 100 through a second opening 121 of the flow top cover component 101.

[0195] In some examples, sensor component 103 may include one or more bonding pads (e.g., bonding pad 127). In some examples, flow top cover component 101 may isolate bonding pad 127 from flow channel 125, for example, to protect these bonding pads from liquid and to make bonding pad 127 available for lead bonding.

[0196] In some examples, a first tube may be connected to a first end of a flow channel, and a second tube may be connected to a second end of the flow channel, such that an exemplary flow medium may enter the exemplary flow sensing device through one of these tubes, travel through the flow channel, and exit the exemplary flow sensing device through the other tube. In some examples, the first and / or second tubes may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics.

[0197] Re-reference Figures 1A to 1D As described above, the first portion of the flow channel may include multiple sidewalls. In some examples, these multiple sidewalls may extend along the central axis of the flow channel. In various examples of this disclosure, the cross-section of the flow channel (e.g., along axis A-A') may include various shapes.

[0198] In some examples, the heating element may be disposed on a thin film or surface of a wafer included, for example, in sensor component 103. In some examples, the heating element may be miniature in size. In some examples, the heating element may comprise a single metal strip or multiple metal strips. In some examples, the heating element may comprise an embedded wire or strip in one of the flow top cover component 101 or sensor component 103. In some examples, the heating element may comprise a coil, strip, plate, wiring strip, and / or layer that can be connected to a power source. When the power is turned on, current may flow through the coil, strip, plate, wiring strip, and / or layer, which in turn converts electrical energy into heat energy.

[0199] In some examples, the heating element may comprise nickel-based and / or iron-based materials. For instance, the heating element may comprise a nickel-iron (NiFe) alloy, which provides a high temperature coefficient of resistance.

[0200] While the above description provides some examples of heating elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, exemplary heating elements may include one or more additional and / or alternative elements, one or more additional and / or alternative materials, and / or may be in other forms.

[0201] While the above description provides exemplary flow top cover components and / or sensors including a heating element, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary flow top cover component or sensor component may include two or more heating elements.

[0202] For example, a thermal sensing element may include one or more thermopile elements. In such examples, an exemplary thermopile element may include one or more thermocouples connected in series or parallel, which may detect, measure, and / or identify thermal energy, and may convert thermal energy into electrical energy and / or generate one or more electrical signals based on the detected / measured / identified thermal energy.

[0203] While the above description provides some examples of thermal sensing elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, exemplary thermal sensing elements may include one or more additional and / or alternative elements, one or more additional and / or alternative materials, and / or may be in other forms. For example, exemplary thermal sensing elements may include at least one temperature sensing circuit, such as, but not limited to, a thermopile, a resistor, a diode, a resistor in a Wheatstone bridge circuit, or a thermistor.

[0204] While the above description provides exemplary sensor components including one, two, three, or four thermal sensing elements, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary sensor component may include more than four thermal sensing elements. In some examples, the exemplary sensor component may include more than two thermal sensing elements upstream of a heating element. In some examples, the exemplary sensor component may include more than two thermal sensing elements downstream of a heating element. In some examples, the exemplary sensor component may include a number of thermal sensing elements upstream of a heating element that differs from the number of thermal sensing elements downstream of the heating element. In some examples, two or more thermal sensing elements may be positioned upstream of a heating element, while no thermal sensing elements are positioned downstream of the heating element. In some examples, two or more thermal sensing elements may be positioned downstream of a heating element, while no thermal sensing elements are positioned upstream of the heating element. In some examples, the upstream thermal sensing elements and / or the downstream thermal sensing elements may be electrically connected in series or in parallel.

[0205] In some examples, the thermal sensing element may be disposed in a layer of the sensor component separate from the layer where the heating element is located. In some examples, the separate layer of the sensor component including the thermal sensing element may comprise one or more suitable materials, including but not limited to silicon nitride, silicon oxide, silicon oxynitride, polymers, or other electrically insulating films. In some examples, the separate layer of the sensor component including the thermal sensing element may be an encapsulation layer that protects the thermal sensing element, and this encapsulation layer may comprise a metal that can be corroded by moisture and other chemicals. In some examples, the encapsulation layer may be electrically insulating.

[0206] In some examples, the thermal sensing element may be electrically coupled to one or more other elements (e.g., power supply, processor) based on technologies such as, but not limited to, through-glass vias (TGV), through-silicon vias (TSV), and / or aerosol or inkjet printing. Alternatively, the thermal sensing element may be electrically coupled to one or more other elements via other means.

[0207] In some examples, the flow top cover component may include a first layer with a heating element, while the sensor component includes a second layer with a thermal sensing element. In some examples, the sensor component may include both the first and second layers. In some components, the first and second layers may be non-coplanar. In other words, the first layer including the heating element may not occupy the same plane as the second layer including the thermal sensor element.

[0208] According to various examples of this disclosure, one or more plate elements may be disposed in an exemplary sensor component of an exemplary flow sensing device. In this disclosure, the term "plate element" refers to a piece of material that may be in the form of a plate. In some examples, the plate element may facilitate heat transfer from the flow medium in the flow channel to the sensing element in the sensor component. For example, at least one plate element may be disposed on a third layer of the exemplary sensor component, and said at least one plate element may at least partially overlap with at least one thermal sensing element disposed in a second layer of the exemplary sensor component.

[0209] Now for reference Figure 2The diagram illustrates a cross-section of an exemplary flow sensor device 200. In some examples, the flow sensor device 200 may include a flow top cover component 201 and a sensor component 203. In some examples, the flow top cover component 201 may be configured to be operatively coupled to the sensor component 203. In some examples, the flow top cover component 201 may be configured to be removably coupled, adhesively coupled, permanently coupled, attached, joined, or otherwise disposed to at least a portion of the top surface of the sensor component 203. In some examples, the flow top cover component 201 may define or partially define a flow path 217. In some examples, a portion of the top surface of the sensor component 203 may partially define the flow path 217. In some examples, a cavity 228 may be defined in at least a portion of the sensor component 203. In some examples, the cavity 228 may be defined by an aperture in the bottom surface of the sensor component 203, wherein the bottom surface is opposite the top surface of the sensor component 203. In some examples, the cavity 228 may be formed by removing material from the sensor component 203. In some examples, the flow top cover component 201 may be disposed on a first portion of the top surface of the sensor component 203, and one or more engagement pads 227 may be formed or disposed on a second portion of the top surface of the sensor component 203. In some examples, the one or more engagement pads 227 may be used to connect circuit elements to external circuitry, for example, via wire bonding, pins, spring clips, or any other suitable electrical contact means. In some examples, the one or more engagement pads 227 may maintain physical and / or thermal isolation from heating elements, etc., so that the electrical connection to external circuitry, etc., is not disrupted by the heat emitted by the heating elements. In some examples, the flow sensor device 200 may include one or more thermal sensor elements, which may include one or more thermopiles, resistors, etc.

[0210] In various examples of this disclosure, the exemplary dimensions of the exemplary cross-section of the exemplary flow channel may be from micrometers to hundreds of micrometers in height and from tens of micrometers to hundreds of micrometers in width. In various examples of this disclosure, the length of the exemplary flow channel may be greater than one hundred micrometers.

[0211] While the above description provides exemplary dimensions of exemplary flow channels, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary dimensions of the exemplary flow channels may have other values.

[0212] According to other embodiments, systems, devices, and methods can be provided to improve the accuracy of thermopile-based flow sensing devices and facilitate accurate measurement of low fluid flow rates. In some embodiments, the signal generated by the thermopile-based flow sensing device disclosed herein, using a thermocouple or thermopile, is a voltage source and has minimal response to membrane resistance. Without membrane resistance sensitivity, other sensitivities (such as stress or magnetoresistance changes) are negligible. An additional thermocouple can provide additional voltage, signal, and sensitivity, an advantage that conventional resistive flow sensors do not offer in terms of sensitivity. In some cases, the thermopile structure can be fabricated on a microbridge structure or membrane structure. In some embodiments, the membrane structure disclosed herein can provide the same thermopile structure as a microbridge, as well as other structures that a microbridge cannot provide.

[0213] In some implementations, the general process for manufacturing a thermopile flow sensor includes:

[0214] a. Growth of thermal silica.

[0215] b. Deposit silicon nitride at the bottom. In some implementations, silicon dioxide can be used instead of silicon nitride dielectric, such as by PECVD, tetraethoxysilane (TEOS), or sputtering deposition, to reduce thermal conductivity.

[0216] c. Deposit and pattern the resistance heater structure. The heater structure can be made of materials such as: silicon (including polycrystalline silicon); platinum; nickel-chromium alloys; permalloy; PtSi and other silicides; W; TiN; AlN; WN; any other suitable material; or any combination thereof.

[0217] d. Deposit silicon nitride interlayer dielectric.

[0218] e. Depositing and patterning the first thermocouple material. This paper discusses in more detail the various thermocouple materials that can be used for the first thermocouple.

[0219] f. Deposit interlayer dielectric. In some cases, depending on the materials used, this step may be optional but can result in higher yields. In some cases, if an interlayer dielectric is used, it must be patterned to open vias to the underlying thermocouple material.

[0220] g. Depositing and patterning the second thermocouple material. This paper discusses in more detail the various thermocouple materials that can be used for the second thermocouple.

[0221] h. Deposit interlayer dielectrics, patterns, and open vias onto the heater and thermopile connections.

[0222] i. Deposit metal (such as Al / 1% Cu) and pattern it to form lead-out lines and bonding pads.

[0223] j. Deposit a silicon nitride overlay and pattern it to open up the bonding pad area.

[0224] k. Pattern the back side of the wafer and use deep reactive ion etching (DRIE) to create a cavity beneath the thermopile structure.

[0225] In some embodiments, the heater structure may be located above or below a single set of thermocouples (e.g., one thermocouple), or above or below multiple sets of thermocouples, with one side upstream of the heater structure and the other side downstream. In these arrangements, the thermocouples are not located on the silicon die. Instead, in some examples, the thermocouples are suspended on the cavity or reside on the membrane structure. In some embodiments, the set of thermocouples may be collectively referred to as a thermopile. In some embodiments, the thermopile may be placed on a thermally insulating structure (such as a bridge or membrane), wherein opposing thermocouples (e.g., cold junctions, hot junctions) are oriented such that one set of junctions is upstream and the other set is downstream of the heating element centerline. In some examples, the flow sensor device 200 may include one or more thermopiles positioned entirely upstream of the heating element centerline and one or more thermopiles positioned entirely downstream of the heating element centerline.

[0226] In some implementations, the heater structure may be located between two sets of thermocouples (e.g., two thermopile structures), with one set of thermocouples upstream of the heater structure and the other set downstream. In these arrangements, parasitic effects exist, and each set of thermocouples has one side on the bulk silicon die that fluctuates in temperature.

[0227] In some implementations, the following formula can be used to characterize the thermopile-based flow sensing device disclosed herein:

[0228] ΔV = nΔS(ΔT)

[0229] Where ΔV = potential difference; n = number of thermocouples; S = Seebeck coefficient (also known as thermal power, thermoelectric power (TE) or thermoelectric sensitivity); ΔS = TE1 - TE2 (thermoelectric power of the first thermoelectric material - thermoelectric power of the second thermoelectric material); T = temperature; and ΔT = T1 - T ref (Measured temperatures at (multiple) thermojunctions - temperatures at (multiple) reference thermojunctions). In some cases, T1 can be measured on the film structure using a downstream thermocouple, and T... ref The downstream thermocouple junction can be used for measurement on bulk silicon. In other cases, the relative temperature difference ΔT can be measured on the film structure using both the upstream and downstream thermocouple junctions without using a reference temperature; however, in some cases, the heater temperature is measured using a separate thermocouple.

[0230] Although this disclosure describes the features of the thermopile-based flow sensing device disclosed herein with reference to flow sensors, the thermopile-based flow sensing device disclosed herein can be used in the testing or application of any suitable sensor, detector, gauge, instrument, utilizing precise heating or temperature detection, or other applications where such use is required.

[0231] In some embodiments, the heater structure may be located between three or more sets of thermocouples (e.g., three or more thermocouples), wherein at least one set of thermocouples is located upstream of the heater structure, and two or more other sets of thermocouples are located downstream of the heater structure, or at least one set of thermocouples is located downstream of the heater structure and at least one set of thermocouples is located upstream of the heater structure. In these arrangements, parasitic effects may exist, and each set of thermocouples may have one side on the bulk silicon die that fluctuates in temperature.

[0232] In some implementations, the following formula can be used to characterize the thermopile-based flow sensing device disclosed herein:

[0233] ΔV=n·S·(ΔT)=n·S·(T A –T0)

[0234] Where ΔV = potential difference; n = number of thermocouples; S = Seebeck coefficient (also known as thermal power, thermoelectric power (TE) or thermoelectric sensitivity); T = temperature; and ΔT = T A –T0(Measured temperature at the thermojunction - Reference temperature at the thermojunction). In some cases, T A Measurements can be taken on the film structure T0 within the sensing region 123 using a downstream thermocouple, and measurements can also be taken on bulk silicon using a downstream thermocouple. In other cases, the relative temperature difference ΔT can be measured on the film structure using both the upstream and downstream thermocouples without using a reference temperature. In some examples, T... A T0 can be considered an active junction or a hot junction because it is affected by the heating element, while T0 can be considered a reference junction or a cold junction because it is located outside the sensing area 123 and is not affected by the heating element.

[0235] In some embodiments, exemplary thermocouple materials may include at least one or more metallic or inorganic components. For example, one or more thermocouple materials may be used to provide a thermocouple junction comprising an interface between a first thermocouple material and a second thermocouple material. In some embodiments, the number of thermocouple junctions in the thermocouple stack of the example flow sensing device based on a thermocouple stack disclosed herein may depend on the Seebeck coefficients of the thermocouple materials in the thermocouple and the desired output voltage (e.g., it may be a function of them). The term "dS" refers to the difference between the Seebeck coefficients of the thermocouple materials in the thermocouple.

[0236] In some embodiments, the first thermocouple material may include polycrystalline silicon, and the second thermocouple material may include aluminum. In some embodiments, the first and second thermocouple materials may include polycrystalline silicon with different doping (e.g., n-type and p-type polycrystalline silicon). For example, the first thermocouple material may include n-type polycrystalline silicon (nPoly Si), and the second thermocouple material may include p-type polycrystalline silicon (pPoly Si). In another example, the first thermocouple material may include p-type polycrystalline silicon (pPoly Si), and the second thermocouple material may include n-type polycrystalline silicon (nPoly Si).

[0237] In some embodiments, the first thermocouple material may include a nickel-iron alloy (e.g., 60:40NiFe, 80:20NiFe), and the second thermocouple material may include chromium (Cr), wherein dS is about 65 μV / C for 60:40NiFe and Cr or about 53 μV / C for 80:20NiFe and Cr. In some embodiments, the first thermocouple material may include a nickel-iron alloy (e.g., 60:40NiFe, 80:20NiFe), and the second thermocouple material may include chromium disilicide (CrSi2), wherein dS is about 105 μV / C for 60:40NiFe and CrSi2 or about 93 μV / C for 80:20NiFe and CrSi2. In some embodiments, the first thermocouple material may include a nickel-iron alloy (e.g., 60:40NiFe, 80:20NiFe), and the second thermocouple material may include rhenium disilicide (ReSi2).

[0238] In some embodiments, the first thermocouple material may include chromium nitride (e.g., CrN), and the second thermocouple material may include copper (Cu), wherein the dS is about 146 μV / C for CrN and Cu. In some embodiments, the first thermocouple material may include chromium nitride (e.g., CrN), and the second thermocouple material may include aluminum (Al), wherein the dS is about 138 μV / C for CrN and Al. In some embodiments, the first thermocouple material may include chromium nitride (e.g., CrN), and the second thermocouple material may include p-type polycrystalline silicon (pPoly Si), wherein the dS is about 270 μV / C for CrN and pPoly Si.

[0239] In some embodiments, the first thermocouple material may include copper (Cu), and the second thermocouple material may include a copper-nickel alloy (e.g., constantan).

[0240] In some implementations, the thermopile-based flow sensing device disclosed herein may include any combination of components, structures, and features discussed with reference to the exemplary thermopile-based flow sensing device described herein and other exemplary thermopile-based flow sensing devices, including the addition or omission of components, structures, and features.

[0241] exist Figure 2 In the example shown, the exemplary flow sensing device 200 may include components similar to those described above. Figure 1A and Figure 1B The sensor component 103 and the flow top cover component 101 are sensor component 203 and flow top cover component 201, respectively.

[0242] For example, the flow top cover component 201 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics. Alternatively, the sensor component 203 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics.

[0243] For example, the flow top cover component 201 may include a flow channel portion on a second surface of the flow top cover component 201. The flow top cover component 201 may be bonded to a first surface of the sensor component 203. In some examples, the flow channel portion of the flow top cover component 201 and the first surface of the sensor component 203 may form at least a first portion of the flow channel 217.

[0244] In some examples, the first portion of the flow channel may be orthogonal to the central axis of the flow channel 217 and may have any suitable size and any suitable shape factor, such as a rectangular shape or a rectangular prism shape. For example, the flow channel portion of the flow cap component 201 may provide three sidewalls for the flow channel, wherein one of these sidewalls may be arranged orthogonally to the other two sidewalls.

[0245] In some examples, the first portion of the flow channel 217 may include at least one rounded corner or rounded edge. For example, the flow channel portion of the flow top cover component 201 may provide curved sidewalls for the flow channel 217. In some examples, at least one rounded corner or rounded edge may reduce bubble formation within the flow channel 217 and / or reduce the effect of turbulence of the flow medium in the flow channel 217 on reading inaccuracy.

[0246] In some examples, the flow top cover component 201 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics. Alternatively, the sensor component 203 may comprise materials such as, but not limited to, silicon, glass, polymers, and / or plastics.

[0247] While the foregoing description provides exemplary shapes of the cross-section of the first portion of the flow channel, it should be noted that the scope of this disclosure is not limited to the above description. In some examples, the exemplary cross-section of the first portion of the flow channel may include one or more additional and / or alternative shapes, may include one or more protrusions, may include one or more concave or convex surfaces, may include one or more baffles, etc., and / or the first portion of the flow channel may be formed in an additional and / or alternative manner.

[0248] Now for reference Figure 3 This paper presents a transient flow-medium temperature model for exemplary flow sensor devices such as the 100 and 200. The exemplary flow sensor devices are sized and constructed to define a flow channel with a height of approximately 25 μm, which generates a temperature difference (dT) greater than approximately 9 °C at a flow rate of approximately 1 mL / h. At a flow rate of approximately 1 mL / h, the pressure difference (dP) through the flow channel is between approximately 3.5 inches and 4.5 inches of water column. It was determined that shortening the channel length can reduce dP.

[0249] Now for reference Figure 4 It presents the same as Figure 3 The graph illustrates the experimental data associated with the transient flow-medium temperature model and the exemplary flow sensor device described above. As shown, the graph presents experimental results related to the temperature difference experienced by the flow channel at different distances from the heating element at different flow rates between approximately 0.1 mL / hr and approximately 2 mL / hr. Circle T1 indicates the distance of the first thermopile from the heating element, and circle T2 indicates the distance of the second thermopile from the heating element. As shown, the temperature difference between the cold and hot junctions indicates the point of maximum accuracy and / or precision of the reference measurement of temperature change over time, which in turn indicates the change in the flow rate of the flowing medium through the flow channel over time. As shown, if only a single thermopile is used, for example at T1, the accuracy of flow rate measurement at lower flow rates will be difficult to measure because the temperature difference is less pronounced as the flow rate changes at different distances from the heater element T1. However, for the thermopile at a distance of T2, accurate flow rate measurement at lower flow rates is much easier.

[0250] Now for reference Figure 5A transient flow-medium temperature model for exemplary flow sensor devices such as 100, 200, etc., is presented. The exemplary flow sensor devices are sized and constructed to define a flow channel with a height of approximately 90 μm, which generates a temperature difference (dT) greater than approximately 6 °C at a flow rate of approximately 15 mL / hr. The signal associated with a flow rate saturated at approximately 15 mL / hr is determined to be monotonic. When the sensor is placed at a T1 distance of approximately 125 μm from the heater element, a flow rate of approximately 0.5 mL / hr generates a dT of approximately 2.5 °C, which results in a reduction in the accuracy and precision of flow rate measurement at such lower flow rates. Therefore, including a second thermopile located at a T2 distance of approximately 50 μm from the heater element results in an increase in the accuracy and precision of flow rate measurement at lower flow rates, such as approximately 1 mL / hr, which indicates the flow rate for drug administration pumped to a patient.

[0251] Now for reference Figure 6 It presents the same as Figure 5 The graph illustrates the experimental data associated with the transient flow-medium temperature model and the exemplary flow sensor device described above. As shown, the graph presents experimental results related to the temperature difference experienced by the flow channel at different distances from the heating element at different flow rates between approximately 0.1 mL / hr and approximately 20 mL / hr. As shown, circle T1 indicates the distance of the first thermopile from the heating element, and circle T2 indicates the distance of the second thermopile from the heating element. As shown, the temperature difference between the cold and hot junctions indicates the point of maximum accuracy and / or precision of the reference measurement of temperature change over time, and the temperature change over time indicates the change in flow rate of the flowing medium through the flow channel over time. As shown, if only a single thermopile is used, for example at T1, the accuracy of flow rate measurement at lower flow rates will be difficult to measure because the temperature difference change is not significant as the flow rate varies at distances from the heater element T1. However, for the thermopile at distance T2, it is easier to accurately measure the flow rate at lower flow rates.

[0252] Now for reference Figure 7 A transient flow-medium temperature model for exemplary flow sensor devices such as the 100 and 200 is presented. The dimensions and construction of this exemplary flow sensor device are designed to define a flow channel with a height of approximately 350 μm, which generates a temperature difference (dT) of approximately 6 °C for a thermopile positioned at a distance of approximately 50 μm from the heater element at a flow rate of approximately 1,000 mL / h, but the signal saturates at approximately 250 mL / h. This means that a second thermopile at a distance of approximately 125 μm (T2) can improve accuracy at higher flow rates. At a distance of 25 μm from the heater element, the thermopile is able to achieve signal saturation of approximately 5 °C dT at a flow rate of approximately 500 mL / h.

[0253] Now for reference Figure 8 It presents the same as Figure 7 The graph illustrates experimental data associated with the transient flow-medium temperature model and the aforementioned exemplary flow sensor device. As shown, the graph presents experimental results related to the temperature difference experienced by the flow channel at different distances from the heating element at different flow rates of the flowing medium between approximately 10 mL / hr and approximately 1,000 mL / hr. As shown, circle T1 indicates the distance of the first thermopile from the heating element, and circle T2 indicates the distance of the second thermopile from the heating element. As shown, the temperature difference between the cold and hot junctions indicates the point of maximum accuracy and / or precision of the reference measurement of temperature change over time, and the temperature change over time indicates the change in flow rate of the flowing medium through the flow channel over time. As shown, if only a single thermopile is used, for example at T1, the accuracy of flow rate measurement at lower flow rates will be difficult to measure because the temperature difference change is not significant as the flow rate varies at distances from the heater element T1. However, for the thermopile at distance T2, it is easier to accurately measure the flow rate at lower flow rates.

[0254] Now for reference Figure 9A The diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with two sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance between the thermopile sensing elements and the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 1,000 mL / h. Figure 9A The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0255] Now for reference Figure 9BThe diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with three sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance between the thermopile sensing elements and the center of the heating element, and as a function of flow rates ranging from approximately 0.1 mL / h to approximately 1,000 mL / h. Figure 9A The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0256] Now for reference Figure 10 The image shows a top view of a portion of an exemplary flow sensor device 300, which includes a sensor component 303 on which a heater element 305 is disposed. Arrows labeled "flow" indicate the direction of flow of the flow medium through the flow channel, but do not indicate the relative position, location, size, or other factor or characteristic of the flow channel or flow medium relative to the heating element 305. In some examples, the heater element 305 is disposed on or within a sensing region 323, including a membrane or the like. In some examples, the sensing region 323 may include an upstream region and a downstream region relative to the direction of flow of the flow medium through a nearby flow channel. In some examples, one or more thermopiles may be disposed within or partially disposed within the sensing region 323 in the upstream region, and one or more other thermopiles may be disposed within or partially disposed within the sensing region 323 in the downstream region. In some examples, distances T1 and T2 from the heater element may be established in both the upstream and downstream regions. In some examples, the first end and / or first portion of the first thermopile or other such heat-sensing element may be positioned in the upstream region of the sensing region 323 at a distance from the heater element 305T1, and the second end or second portion of the first thermopile may be positioned outside the sensing region 323, such as... Figure 10As shown at T0. In some examples, T0 can be used as a reference temperature. In some examples, the temperature of the substrate at T0 can be used as a reference temperature to compare the temperature difference between two thermopile, etc., and can be used during the calibration of the flow sensor. In some examples, a first end or a first portion of the second thermopile can be positioned in the upstream region of the sensing region 323 at a distance from the heater element 305T2, and a second end or a second portion of the second thermopile can be positioned outside the sensing region 323 at T0. In some examples, the end of the thermopile can be the location where the temperature is sensed.

[0257] In some examples, the first thermopile is approximately 50 μm away from the heater element at distance T1, and the second thermopile is approximately 125 μm away from the heater element at distance T2. However, in other examples, the distance T1 can be between approximately 10 μm and approximately 500 μm, between approximately 15 μm and approximately 450 μm, between approximately 20 μm and approximately 400 μm, between approximately 25 μm and approximately 350 μm, between approximately 30 μm and approximately 300 μm, between approximately 35 μm and approximately 250 μm, between approximately 40 μm and approximately 200 μm, between approximately 45 μm and approximately 150 μm, between approximately 50 μm and approximately 100 μm, between approximately 10 μm and approximately 400 μm, or between approximately 10 μm and approximately 10 μm. Any suitable distance between approximately 300 μm, between approximately 10 μm and approximately 200 μm, between approximately 10 μm and approximately 100 μm, between approximately 10 μm and approximately 90 μm, between approximately 10 μm and approximately 80 μm, between approximately 10 μm and approximately 70 μm, between approximately 10 μm and approximately 60 μm, between approximately 10 μm and approximately 50 μm, between approximately 10 μm and approximately 40 μm, between approximately 10 μm and approximately 30 μm, or between approximately 10 μm and approximately 20 μm (including all values ​​and ranges in between).

[0258] In some examples, the distance T2 of the second thermopile from the heater element can be between approximately 100 μm and approximately 1,000 μm, between approximately 100 μm and approximately 950 μm, between approximately 100 μm and approximately 800 μm, between approximately 100 μm and approximately 750 μm, between approximately 100 μm and approximately 700 μm, between approximately 100 μm and approximately 650 μm, or between approximately 100 μm and approximately 100 μm. Between 0 μm and approximately 600 μm, between approximately 100 μm and approximately 550 μm, between approximately 100 μm and approximately 500 μm, between approximately 100 μm and approximately 450 μm, between approximately 100 μm and approximately 400 μm, between approximately 100 μm and approximately 350 μm, between approximately 100 μm and approximately 300 μm, between approximately 100 μm and approximately 250 μm, between approximately 100 μm and approximately 600 μm, between approximately 100 μm and approximately 600 μm, between approximately 100 μm and approximately 600 μm, between approximately 100 μm and approximately 600 μm, between approximately 100 μm and approximately 600 μm, between approximately 100 μm and approximately 65 ... Between approximately 200 μm and 100 μm, between approximately 100 μm and approximately 150 μm, greater than approximately 75 μm, greater than approximately 80 μm, greater than approximately 85 μm, greater than approximately 90 μm, greater than approximately 95 μm, greater than approximately 100 μm, greater than approximately 105 μm, greater than approximately 110 μm, greater than approximately 115 μm, greater than approximately 120 μm, greater than approximately 125 μm, greater than approximately 130 μm, greater than approximately 135 μm, greater than approximately 14 μm Any suitable distance of 0 μm, greater than about 145 μm, greater than about 150 μm, greater than about 175 μm, greater than about 200 μm, greater than about 250 μm, greater than about 300 μm, greater than about 400 μm, greater than about 500 μm, greater than about 600 μm, greater than about 700 μm, greater than about 800 μm, greater than about 900 μm, or greater than about 1,000 μm (inclusive of all values ​​and ranges in between).

[0259] Now for reference Figure 11The image shows a top view of a portion of an exemplary flow sensor device 400, which includes the top surface of a sensor component 403 on which a heater element 405 is disposed. Arrows labeled "flow" indicate the direction of flow of the flow medium through a flow channel, but do not indicate the relative position, location, size, or other factor or characteristic of the flow channel or flow medium relative to the heating element 405. In some examples, the heater element 405 is disposed on or within a sensing region 423, including a membrane or the like. In some examples, the sensing region 423 may include an upstream region and a downstream region relative to the direction of flow of the flow medium through a nearby flow channel. In some examples, one or more thermopiles may be disposed within or partially disposed within the sensing region 423 in the upstream region, and one or more other thermopiles may be disposed within or partially disposed within the sensing region 423 in the downstream region. In some examples, distances T1 and T2 from the heater element may be established in both the upstream and downstream regions. In some examples, a first end or portion of the first thermopile or other such heat-sensing element may be positioned in the upstream region of the sensing region 423 at a distance from the heater element 405T1, and a second end or portion of the first thermopile may be positioned outside the sensing region 423, such as... Figure 11 As shown in T0. In some examples, the first end or first portion of the second thermopile may be located in the upstream region of the sensing region 423 at a distance from the heater element 405T2, and the second end or second portion of the second thermopile may be located outside the sensing region 423 at T0.

[0260] For example, such as Figure 11As shown, a first thermocouple stack 411 may be disposed upstream of heater element 405. In some examples, the first thermocouple stack 411 may include a first thermocouple material 411b having a first end serving as a current input terminal 411a and a second end coupled to a first contact material 411c, which bonds the second end of the first thermocouple material 411b to the first end of a second thermocouple material 411d. The second thermocouple material 411d may be bonded to the second end of the first thermocouple material 411b at its first end via the first contact material 411c. The second thermocouple material 411d may include a second contact material 411e at its second end, the second contact material 411e being configured to contact the transmitting end electrical portion of the second thermocouple material 411d to the first end of a third thermocouple material 411f. In some examples, the third thermocouple material 411f may include the same or similar material as the first thermocouple material 411b or the second thermocouple material 411d. In some examples, each of the first thermocouple material 411b, the second thermocouple material 411d, and the third thermocouple material 411f may be different. In some examples, the third thermocouple material 411f may be electrically coupled at its second end to a third contact material 411g, which is configured to bond the second end of the third thermocouple material 411f to the first end of a fourth thermocouple material 411h. The fourth thermocouple material 411h may be electrically coupled at its second end to the first end of a fifth thermocouple material 411j via a fourth contact material 411i. The fifth thermocouple material 411j may be electrically coupled at its second end to the first end of a sixth contact material 411l via a fifth contact material 411k. The second end of the sixth contact material 411l may contact or define the current output of the first thermopile 411. In some examples, the first end of the first thermocouple material 411b, the second end of the second thermocouple material 411d, the first end of the third thermocouple material 411f, the second end of the fourth thermocouple material 411h, the first end of the fifth thermocouple material 411j, and the second end of the sixth thermocouple material 411l may be disposed outside the sensing region 423 at a distance T0. In some examples, the second ends of the first thermocouple material 411b, the first end of the second thermocouple material 411d, the second end of the third thermocouple material 411f, the first end of the fourth thermocouple material 411h, the second end of the fifth thermocouple material 411j, and the first end of the sixth thermocouple material 411l may be disposed upward along the dashed line T1 within the sensing region 423, such that all parts of the first thermocouple stack 411 are spaced apart from the heater element 405 by a minimum distance T1.

[0261] In some examples, the flow sensor device 400 may also include a second thermopile 412 disposed upstream and including a similar thermocouple material configuration as discussed above with reference to the first thermopile 411.

[0262] In some examples, at least one end of each different thermocouple material element of the second thermopile 412 may be positioned outside the sensing region 423, while the other end of each different thermocouple material element of the second thermopile 412 may be located in the upstream region of the sensing region 423 and positioned upward along the dashed line T2, such that all parts of the second thermopile 412 are spaced apart from the heater element 405 by a minimum distance of T2.

[0263] In some examples, the flow sensor device 400 may also include a third thermopile 413 disposed downstream and comprising a similar thermocouple material configuration as discussed above with reference to the first thermopile 411.

[0264] In some examples, at least one end of each different thermocouple material element of the third thermopile 413 may be positioned outside the sensing region 423, while the other end of each different thermocouple material element of the third thermopile 413 may be located in the downstream region of the sensing region 423 and positioned downward along the dashed line T1, such that all parts of the third thermopile 413 are spaced apart from the heater element 405 by a minimum distance of T1.

[0265] In some examples, the flow sensor device 400 may also include a fourth thermopile 414 disposed downstream and comprising a similar thermocouple material configuration as discussed above with reference to the first thermopile 411. In some examples, at least one end of each different thermocouple material element of the fourth thermopile 414 may be positioned outside the sensing region 423, while the other end of each different thermocouple material element of the fourth thermopile 414 may be located in the downstream region of the sensing region 423 and positioned downward along the dashed line T2, such that all portions of the fourth thermopile 414 are spaced apart from the heater element 405 by a minimum distance T2.

[0266] Therefore, the voltage change across each of the first thermopile 411, the second thermopile 412, the third thermopile 413, and the fourth thermopile 414 can be determined by inputting a corresponding current or signal with a known voltage to the corresponding input terminal (e.g., 411a) of each different thermopile and measuring the voltage or signal in response to the current received at the corresponding output terminal of each different thermopile. Figure 11 As shown, the voltage change V up1 V up2 V down1 and V down2 These are respectively associated with the first thermopile 411, the second thermopile 412, the third thermopile 413, and the fourth thermopile 414. In some examples, V can be... up1 and V up2 Summation is performed to determine the upstream voltage, and V can be used to determine the upstream voltage. down1 and Vdown2 The values ​​are summed to determine the downstream voltage. In some examples, the difference between the upstream and downstream voltages can indicate the flow rate of the medium through adjacent flow channels.

[0267] Now for reference Figure 12 An exemplary flow sensor device 500 with a configuration similar to that of flow sensor device 400 is shown. However, the first thermopile 411 and the second thermopile 412 of flow sensor device 400 are nested within each other or overlap according to their position along the length of heater element 405, and the third thermopile 413 and the fourth thermopile 414 of flow sensor device 400 are nested within each other or overlap according to their position along the length of heater element 405. Instead, flow sensor device 500 includes a first thermopile 511 that does not overlap and is not nested within the second thermopile 512 in the upstream direction, and also includes a third thermopile 513 that does not overlap and is not nested within the fourth thermopile 514 in the downstream direction. In some examples, the first thermopile 511 and the second thermopile 512 may be nested or overlapped, while the third thermopile 513 and the fourth thermopile 514 are not nested or overlapped. In other examples, the third thermopile 513 and the fourth thermopile 514 may be nested or overlapped, while the first thermopile 511 and the second thermopile 512 may not be nested or overlapped.

[0268] In some examples, the flow sensor devices 400 and 500 can be bidirectional. In some examples, the flow sensor devices 400 and 500 can measure flow in the upstream direction or flow in the downstream direction.

[0269] Now for reference Figure 13 An exemplary flow sensor device 600 with a configuration similar to flow sensor device 400 is shown. However, flow sensor device 600 includes a third thermopile 613 nested or overlapping with the fourth thermopile 614 in the downstream direction of heater element 605, but does not include a first thermopile 611 or a second thermopile 612 in the upstream direction of heater element 605. In some examples, the flow rate of the flowing medium in the nearby flow channel can be determined simply by summing Vdown1 and Vdown2 without determining the difference between the upstream and downstream voltage drops across the thermopile.

[0270] Now for reference Figure 14An exemplary flow sensor device 700 with a configuration similar to flow sensor device 500 is shown. However, flow sensor device 700 includes a third thermopile 713 that does not nest or overlap with a fourth thermopile 714 in the downstream direction of heater element 705, but is not included in the first thermopile 711 or the second thermopile 712 in the upstream direction of heater element 705. In some examples, the flow rate of the flowing medium in the nearby flow channel can be determined simply by summing Vdown1 and Vdown2 without determining the difference between the upstream and downstream voltage drops across the thermopile.

[0271] Although flow sensor devices 600 and 700 are described as including thermopile only in the downstream direction of heater elements 605, 705, other exemplary flow sensor devices may include thermopile only in the upstream direction of heater elements 605, 705.

[0272] In some examples, flow sensor devices 600 and 700 may be unidirectional. In some examples, flow sensor devices 600 and 700 may be configured to measure flow rate only in a single direction, such as by... Figure 13 and Figure 14 The direction indicated by the flow direction arrow at the bottom.

[0273] Now for reference Figure 15 and Figure 16 An exemplary perspective view of at least a portion of an exemplary flow sensing device is provided. It should be noted that, since these are perspective views, the heating element is shown as a projection relative to the plane of the heat sensing element.

[0274] For example, Figure 15 The heating elements 802 and 804 are shown as projections relative to the plane of the sensing element. For example, Figure 16 The heating elements 901 and 903 are shown as projections relative to the plane of the sensing element. In other words, in the exemplary flow sensing device, the heating element and the sensing element are not coplanar.

[0275] Now for reference Figure 15 An exemplary perspective view of at least a portion of an exemplary flow sensing device 800 is shown. Specifically, Figure 15 An exemplary top perspective view of at least a portion of an exemplary flow sensing device 800 is shown, wherein components of the exemplary flow sensing device 800 are projected onto the same plane.

[0276] In some examples, the exemplary flow sensing device 800 may include one or more heating elements disposed in the flow top cover component, similar to those described above. Figure 1DThose mentioned above. For example, an exemplary flow sensing device 800 may include a first heating element 802 and a second heating element 804. Figure 15 In the example shown, the first heating element 802 and / or the second heating element 804 may each include a metal layer comprising a nickel-based and / or iron-based material (e.g., a nickel-iron (NiFe) alloy).

[0277] In some examples, the exemplary flow sensing device 800 may include one or more thermal sensing elements disposed in a sensor component, similar to those described above. Figure 1D Those mentioned above. For example, the thermal sensing element of the exemplary flow sensing device 800 may be in the form of one or more thermopile elements, including a first thermopile element 806, a second thermopile element 808, and / or a resistor element 810.

[0278] As described above, one or more plate elements may be disposed in an exemplary sensor component of an exemplary flow sensing device. Figure 15 In the example shown, the first plate element 812, the second plate element 814, and / or the third plate element 816 may be disposed in the exemplary sensor component.

[0279] In some examples, the first plate element 812, the second plate element 814, and / or the third plate element 816 may cover only the thermocouples of each thermopile on the film of the sensor component, rather than the thermocouples of the thermopile on the substrate of the sensor component. In such examples, these plate elements must reside only on the film and may not contact the substrate portion of the sensor component, since heat will subsequently be transferred to the substrate.

[0280] Although Figure 15 The example shown illustrates an elliptical shape for the first plate element 812 and / or the second plate element 814, but it should be noted that the scope of this disclosure is not limited to elliptical shapes only. In addition to or alternatively, the first plate element 812 and / or the second plate element 814 may be other shapes, including squares, rectangles and / or circles.

[0281] In some examples, the first plate element 812 may be disposed on a third layer of the exemplary sensor component, and the first thermopile element 806 may be disposed on a second layer of the exemplary sensor component. In some examples, the conductive plate (e.g., the first plate element 812) may not be in close contact with the thermopile material (e.g., the first thermopile element 806), but a thin-film electrical insulator, such as silicon nitride, must be present between the thermopile material and the plate material. Figure 15 In the example shown, when the first plate element 812 is projected onto the plane of the first thermopile element 806, the first plate element 812 may at least partially overlap with the first thermopile element 806.

[0282] In some examples, the first plate element 812 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the first plate element 812 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the first plate element 812 may be in contact with a flow medium in a flow channel, and the first plate element 812 may comprise an inert material (e.g., gold).

[0283] In some examples, the exemplary sensor component may further include an insulating layer disposed between the first plate element 812 and the first thermopile element 806 (e.g., between the second layer and the third layer of the sensor component). In some examples, the insulating layer may comprise a material that provides electrical insulation (e.g., silicon oxide, silicon nitride, silicon oxynitride, etc.). As described above, the first plate element 812 may comprise a metallic material. Therefore, the insulating layer prevents the first plate element 812 from short-circuiting the first thermopile element 806.

[0284] Re-reference Figure 15 The second plate element 814 may be disposed on the third layer of the exemplary sensor component, and the second thermopile element 808 may be disposed on the second layer of the exemplary sensor component. In some examples, the conductive plate (e.g., the second plate element 814) may not be in close contact with the thermopile material (e.g., the second thermopile element 808), but a thin-film electrical insulator, such as silicon nitride, must be present between the thermopile material and the plate material. Figure 15 In the example shown, when the second plate element 814 is projected onto the plane of the second thermopile element 808, the second plate element 814 may at least partially overlap with the second thermopile element 808.

[0285] Similar to the first plate element 812 described above, in some examples, the second plate element 814 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the second plate element 814 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the second plate element 814 may be in contact with the flow medium in the flow channel, and the second plate element 814 may comprise an inert material (e.g., gold).

[0286] In some examples, exemplary sensor components may also include an insulating layer disposed between the second plate element 814 and the second thermopile element 808 (e.g., between the second layer and the third layer of the sensor component), similar to those described above.

[0287] Re-reference Figure 15The third plate element 816 may be disposed on the third layer of the exemplary sensor component, and the resistor element 810 may be disposed on the second layer of the exemplary sensor component. In some examples, the second layer may be above the third layer. In some examples, the second layer may be below the third layer. Figure 15 In the example shown, the third plate element 816 may at least partially overlap with the resistor element 810.

[0288] Similar to the first plate element 812 described above, in some examples, the third plate element 816 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the third plate element 816 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the third plate element 816 may be in contact with the flow medium in the flow channel, and the third plate element 816 may comprise an inert material (e.g., gold).

[0289] In some examples, the exemplary sensor component may also include an insulating layer disposed between the third plate element 816 and the resistor element 810 (e.g., between the second and third layers of the sensor component), similar to those described above. In some examples, it may be necessary to position the third plate element 816 to overlap with the resistor lines of the resistor element 810, but not with the wide leads of the resistor element 810, which are used for connections between the resistor element 810 and other devices (e.g., an ohmmeter).

[0290] Now for reference Figure 16 An exemplary perspective view of at least a portion of an exemplary flow sensing device 900 is shown. Specifically, Figure 16 An exemplary top perspective view of at least a portion of an exemplary flow sensing device 900 is shown, wherein components of the exemplary flow sensing device 900 are projected onto the same plane.

[0291] In some examples, the exemplary flow sensing device 900 may include one or more heating elements disposed in the flow top cover component, similar to those described above. Figure 1C Those mentioned above. For example, an exemplary flow sensing device 900 may include a first heating element 901 and a second heating element 903. Figure 16 In the example shown, the first heating element 901 and / or the second heating element 903 may each include a metal layer comprising a nickel-based and / or iron-based material (e.g., a nickel-iron (NiFe) alloy).

[0292] In some examples, the exemplary flow sensing device 900 may include one or more thermal sensing elements disposed in a sensor component, similar to those described above. Figure 1CThose mentioned above. For example, the thermal sensing element of the exemplary flow sensing device 900 may be in the form of one or more thermopile elements, including a first thermopile element 905, a second thermopile element 907, and / or a resistor element 909.

[0293] In some examples, Figure 15 An exemplary flow sensing device 800 can generate a ratio Figure 16 The exemplary flow sensing device 900 has a higher span output. This is due to the number of thermopiles that can be fitted onto the membrane in each configuration. Figure 15 The exemplary flow sensing device 800 allows for more thermopile; therefore, the voltage output is higher.

[0294] As described above, one or more plate elements may be disposed in an exemplary sensor component of an exemplary flow sensing device. Figure 16 In the example shown, the first plate element 911, the second plate element 913, and / or the third plate element 915 may be disposed in the exemplary sensor component.

[0295] In some examples, the first plate element 911, the second plate element 913, and / or the third plate element 915 may cover only the thermocouples of each thermopile on the film of the sensor component, rather than the thermocouples of the thermopile on the substrate of the sensor component. In such examples, these plate elements must reside only on the film and may not contact the substrate portion of the die, since heat will subsequently be transferred to the substrate.

[0296] Although Figure 16 The example shown illustrates an elliptical shape for the first plate element 911 and / or the second plate element 913, but it should be noted that the scope of this disclosure is not limited to elliptical shapes only. In addition to or alternatively, the first plate element 911 and / or the second plate element 913 may be other shapes, including squares, rectangles and / or circles.

[0297] In some examples, the first plate element 911 may be disposed on the third layer of the exemplary sensor component, and the first thermopile element 905 may be disposed on the second layer of the exemplary sensor component.

[0298] In some examples, the conductive plate (e.g., first plate element 911) may not be in close contact with the thermopile material (e.g., first thermopile element 905), but a thin-film electrical insulator, such as silicon nitride, must be present between the thermopile material and the plate material. Figure 16 In the example shown, when the first plate element 911 is projected onto the plane of the first thermopile element 905, the first plate element 911 may at least partially overlap with the first thermopile element 905.

[0299] In some examples, the first plate element 911 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the first plate element 911 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the first plate element 911 may be in contact with a flow medium in a flow channel, and the first plate element 911 may comprise an inert material (e.g., gold).

[0300] In some examples, the exemplary sensor component may further include an insulating layer disposed between the first plate element 911 and the first thermopile element 905 (e.g., between the second layer and the third layer of the sensor component). In some examples, the insulating layer may comprise a material that provides electrical insulation (e.g., silicon oxide, silicon nitride, silicon oxynitride, etc.). As described above, the first plate element 911 may comprise a metallic material. Therefore, the insulating layer prevents the first plate element 911 from short-circuiting the first thermopile element 905.

[0301] Re-reference Figure 16 The second plate element 913 may be disposed on the third layer of the exemplary sensor component, and the second thermopile element 907 may be disposed on the second layer of the exemplary sensor component.

[0302] In some examples, the conductive plate (e.g., second plate element 913) may not be in close contact with the thermopile material (e.g., second thermopile element 907), but a thin-film electrical insulator, such as silicon nitride, must be present between the thermopile material and the plate material. Figure 16 In the example shown, when the second plate element 913 is projected onto the plane of the second thermopile element 907, the second plate element 913 may at least partially overlap with the second thermopile element 907.

[0303] Similar to the first plate element 911 described above, in some examples, the second plate element 913 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the second plate element 913 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the second plate element 913 may be in contact with the flow medium in the flow channel, and the second plate element 913 may comprise an inert material (e.g., gold).

[0304] In some examples, exemplary sensor components may also include an insulating layer disposed between the second plate element 913 and the second thermopile element 907 (e.g., between the second layer and the third layer of the sensor component), similar to those described above.

[0305] Re-reference Figure 16The third plate element 915 may be disposed on the third layer of the exemplary sensor component, and the resistor element 909 may be disposed on the second layer of the exemplary sensor component. In some examples, the second layer may be above the third layer. In some examples, the second layer may be below the third layer. Figure 16 In the example shown, the third plate element 915 may at least partially overlap with the resistor element 909.

[0306] Similar to the first plate element 911 described above, in some examples, the third plate element 915 may comprise a non-metallic material with high thermal conductivity (e.g., graphene, diamond, etc.). In some examples, the third plate element 915 may comprise a metallic material (e.g., aluminum, gold, etc.). In some examples, the third plate element 915 may be in contact with the flow medium in the flow channel, and the third plate element 915 may comprise an inert material (e.g., gold).

[0307] In some examples, the exemplary sensor component may also include an insulating layer disposed between the third plate element 915 and the resistor element 909 (e.g., between the second and third layers of the sensor component), similar to those described above. In some examples, it may be necessary to position the third plate element 915 to overlap with the resistor lines of the resistor element 909, but not with the wide leads of the resistor element 909, which connect the resistor element 909 to other devices (e.g., an ohmmeter).

[0308] Now for reference Figure 17This document provides exemplary top views of exemplary heater elements according to some embodiments of the present disclosure. In some examples, the heater element may have a generally rectangular or cylindrical shape. In some examples, the heater element may have an aspect ratio of about 1:17, such as a width of about 12 μm and a length of about 210 μm; however, any and all suitable aspect ratios or other suitable size or shape factors are contemplated. For example, for smaller flow sensor devices, a heating element having a width between about 1 μm and about 10 μm and a length between about 50 μm and about 500 μm may be suitable. Similarly, this paper may also use and envision other aspect ratios, such as those between approximately 1:1 and approximately 1:100, between approximately 1:2 and approximately 1:50, between approximately 1:2 and approximately 1:30, between approximately 1:2 and approximately 1:20, between approximately 1:2 and approximately 1:15, between approximately 1:2 and approximately 1:10, greater than approximately 1:2, greater than approximately 1:5, greater than approximately 1:10, greater than approximately 1:15, greater than approximately 1:20, greater than approximately 1:25, greater than approximately 1:30, greater than approximately 1:40, greater than approximately 1:50, greater than approximately 1:100, less than approximately 1:100, less than approximately 1:50, less than approximately 1:40, less than approximately 1:30, less than approximately 1:30, less than approximately 1:25, less than approximately 1:20, less than approximately 1:15, less than approximately 1:10, or less than approximately 1:5 (including all values ​​and ranges in between). The heater may include one or more metallic materials configured to emit heat energy in the presence of an electric current passing through it, or any other suitable means for generating and emitting heat energy.

[0309] Now for reference Figure 18 Experimental data are provided in the form of graphs to include, for example, Figure 17 The flow sensor device for the heater. Figure 17 The diagram illustrates the mapping between the temperature difference (dT) between the inside and outside of the sensing area of ​​a flow sensing device and the distance of the thermopile from the center of the nearby heating element at various flow rates. For some flow rates, dT peaks at distances between approximately 0.05 mm and approximately 0.1 mm, while a second peak may exist for many flow rates between approximately 0.1 mm and approximately 0.2 mm. In some cases, it is shown that the sensitivity of the thermopile to temperature changes caused by flow rate variations at lower flow rates increases by increasing the distance of the thermopile from the heater element. In other cases, a thermopile positioned closer to the heater may be more effective for higher flow rates because a thermopile at a greater distance may not be heated by the heater, as the faster-flowing medium acts as an effective heat sink.

[0310] Now for reference Figure 19AThe diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with two sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance between the thermopile sensing elements and the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 19A The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0311] Now for reference Figure 19B The diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with three sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance of the thermopile sensing elements from the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 19BThe curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0312] Now for reference Figure 20 This provides exemplary top views of exemplary heater elements according to some embodiments of the present disclosure. In some examples, the heater element may have a generally rectangular or cylindrical shape. In some examples, the heater element may have a width of about 42 μm and a length of about 210 μm; however, any and all suitable aspect ratios or other suitable size or shape factors are contemplated, such as those described above (e.g., referring to heating element 105 and...). Figure 17 (Heating element).

[0313] Now for reference Figure 21 Experimental data are provided in the form of graphs for flow sensor devices that include heater elements, such as... Figure 20 The heater element shown is depicted. Figure 21 The diagram illustrates the relationship between the temperature difference (dT) between the inside and outside of the sensing region or membrane and the distance between the thermopile and the heater element under various flow rates. Figure 21As shown, for some flow rates, dT peaks at distances between approximately 0.05 mm and approximately 0.1 mm, while for many flow rates between approximately 0.1 mm and approximately 0.2 mm, peaks may exist. As illustrated, the sensitivity of a thermopile to temperature changes caused by flow rate variations at lower flow rates can often be increased by increasing the distance between the thermopile and the heater element. In some other cases, while a thermopile positioned closer to the heater may be more effective for higher flow rates, a thermopile located further away may not be heated by the heater, as the faster-flowing medium can act as an effective radiator. For a heater with a width of approximately 42 μm versus one with a width of 12 μm, the wider heater results in a larger temperature difference at higher flow rates, and for thermopiles located further from the heater element, this means that one way to increase the sharpness of the dT peak could be to increase the size of the heater element (and thus increase the heat output), or to add a second heater element, etc. In some examples, if the sharpness of the dT peak can be increased, the distance between the thermopile and the heater element can be determined more accurately, and the thermopile can be positioned to achieve maximum local or overall accuracy and / or precision in temperature measurement, which can translate into increased accuracy and / or precision in flow measurement.

[0314] Now for reference Figure 22A The diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with two sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance between the thermopile sensing elements and the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 22A The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0315] Now for reference Figure 22BThe diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with three sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance of the thermopile sensing elements from the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 22B The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0316] Now for reference Figure 23 This provides exemplary top views of exemplary heater elements according to some embodiments of the present disclosure. In some examples, the heater element may have a generally rectangular or cylindrical shape at one or both ends and include slits or holes through the material. In some examples, the heating element may have a width of about 42 μm and a length of about 210 μm at the inlet and outlet, wherein the gap between the parallel portions of the split heating element is in the middle, each of the parallel split portions having a width of about 20 μm, thus forming an intermediate portion between about 42 μm and about 62 μm; however, any and all suitable aspect ratios or other suitable size or shape factors, such as those described above (e.g., referring to heating element 105 and...), are contemplated. Figure 17 (Heating element).

[0317] Now for reference Figure 24 The experimental data are provided in the form of graphs for a flow sensor device including a split heater element comprising two parallel heating element portions joined together at each end with a gap between them, such as... Figure 23As shown. In this specific embodiment, the split heater has a width of approximately 42 μm and a length of approximately 210 μm, wherein there is a gap of approximately 40 μm between the parallel portions of the split heater element. Figure 24 The diagram shows the relationship between dT and the distance between the thermopile and the heater element under various flow rates. Figure 24 As shown, for some flow rates, dT peaks at distances between approximately 0.05 mm and approximately 0.1 mm, while for many flow rates between approximately 0.1 mm and approximately 0.2 mm, a second peak may exist. The thermopile's sensitivity to temperature changes caused by flow rate variations at lower flow rates can be increased by increasing the distance between the thermopile and the heater element. In some cases, a thermopile positioned closer to the heater may be more effective at higher flow rates because a thermopile at a greater distance may not be heated by the heater, as the faster-flowing medium can act as an effective radiator. For a split heater with a width of approximately 42 μm versus a non-split heater with a width of 12 μm or 42 μm, the split heater results in a larger temperature difference at higher flow rates, and for thermopiles located further from the heater element, this means that another way to increase the sharpness of the dT peak could be to use a split heater in addition to increasing the size of the heater element (and thus increasing the heat output), or to add a second heater element, etc. In some examples, if the sharpness of the dT peak can be increased, the distance between the thermopile and the heater element can be determined more accurately, and the thermopile can be positioned to achieve maximum local or overall accuracy and / or precision in temperature measurement, which can translate into increased accuracy and / or precision in flow measurement.

[0318] Now for reference Figure 25A The diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with two sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance between the thermopile sensing elements and the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 25AThe curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0319] Now for reference Figure 25B The diagram presents graphs of experimental data correlated with temperature variations between the inside and outside of an exemplary flow sensor with three sensing elements positioned at different distances from the center of a heating element. Temperature variations are shown as a function of the distance of the thermopile sensing elements from the center of the heating element, and as a function of flow rates between approximately 0.1 mL / h and approximately 20 mL / h. Figure 25B The curves, showing the distances T1 and T2 of the thermopile from the heating element described herein, can be optimized for various desired flow rates or flow ranges, and the flow sensor devices 100 and 200 can be configured for accurate and precise flow measurement within these flow rates or ranges. In some examples, experimental results may indicate that switching between a first thermopile at a distance T1 and a second thermopile at a distance T2 may be beneficial when the flow rate increases or decreases beyond a certain threshold. In some examples, experimental results may indicate that summing the output voltages of the first upstream thermopile at distance T1 and the second upstream thermopile at distance T2, summing the output voltages of the first downstream thermopile at distance T1 and the second downstream thermopile at distance T2, and determining that the difference between the summed upstream thermopile output voltages and the summed downstream thermopile output voltages results in accurate measurement of flow rate and flow rate changes at higher flow rates exceeding approximately 20 mL / h and at lower flow rates below approximately 20 mL / h.

[0320] In some examples, various applications of this disclosure may require laminar flow, characterized by particles in the flowing medium following a smooth path within the flow channel with little or no mixing (i.e., high momentum diffusion and low momentum identification). In contrast, turbulent flow may be characterized by particles in the flowing medium experiencing irregular fluctuations or mixing. In some examples, laminar flow for flow sensing devices can be implemented based on the flow rate of the flowing medium. As described above, examples of this disclosure can be implemented in infusion pumps where the flow rate may be less than a flow threshold (e.g., 5 ml / h). Thus, turbulence can be avoided by receiving a flow rate below the flow threshold to maintain the flowing medium as laminar.

[0321] While the above description provides an exemplary flow sensing device, it should be noted that the scope of this disclosure is not limited to the exemplary flow sensing device. For example, the scope of this disclosure may cover exemplary methods associated with a flow sensing device.

[0322] For example, according to various examples of this disclosure, a method for manufacturing a flow sensing device can be provided. The method may include: providing a flow top cover component including a heating element disposed in a first layer of the flow top cover component; and providing a sensor component including at least one thermal sensing element disposed in a second layer of the sensor component, similar to the above. Figures 1A to 2 Those described in section 2. For example, the flow top cover component can be formed by the etching process described above. In some examples, the first and second layers are coplanar, similar to the combination above. Figure 1C Those mentioned above.

[0323] In some examples, the method of manufacturing a flow sensor device or assembling a flow sensor device may include bonding a flow top cover component to a first surface of a sensor component.

[0324] In some examples, the exemplary flow sensing device manufactured according to the examples of this disclosure may be in the form of a microelectromechanical system (MEMS) die. For example, a flow top cover component may be integral with the MEMS die. In addition or alternatively, the MEMS die may include one or more other circuits, including but not limited to additional temperature sensing circuitry, communication circuitry (e.g., near field communication (NFC) circuitry), and / or power control circuitry, such that the MEMS die can be integrated into a control system (e.g., a control system for an infusion pump).

[0325] This document describes operations performed according to exemplary embodiments of this disclosure. It should be understood that each operation and combination of operations can be implemented by various means, such as means including hardware, firmware, one or more processors, and / or circuitry associated with the execution of software including one or more computer program instructions. In some embodiments, one or more of the above-described processes can be performed by executing program code instructions. For example, one or more of the above-described processes can be executed by a material handling apparatus (e.g., a robotic arm, servo motor, motion controller, etc.) and computer program instructions residing on a non-transitory computer-readable storage memory. In this regard, program code instructions that, when executed, cause the execution of the above-described processes can be stored by a non-transitory computer-readable storage medium (e.g., memory) of a computing device and executed by the processor of the computing device. In this respect, computer program instructions embodying the above-described processes can be stored by the memory of a device employing embodiments of this disclosure and executed by the processor of the device. It is understood that any such computer program instructions can be loaded onto a computer or other programmable device (e.g., hardware) to produce a machine such that the resulting computer or other programmable device provides an implementation of the functions specified throughout this application. When executed, instructions stored in a computer-readable storage memory produce an article of art configured to implement the various functions specified throughout this application. Program code instructions may also be loaded onto a computer or other programmable device to cause a series of operations to be performed on the computer or other programmable device to produce a computer-implemented process, thereby providing operations for implementing the functions specified in the operations described throughout this application. Furthermore, executing computer or other processing circuitry to perform various functions transforms the computer or other processing circuitry into a specific machine configured to perform the exemplary embodiments of this disclosure.

[0326] The operations and procedures described herein support combinations of means for performing a specified function and combinations of operations for performing a specified function. It will be understood that one or more operations, and combinations of operations, can be implemented by a computer system based on dedicated hardware or a combination of dedicated hardware and computer instructions to perform the specified function.

[0327] In some example implementations, some of the operations described herein may be modified or further amplified as described below. Furthermore, in some implementations, additional optional operations may be included. It should be understood that each of the modifications, optional additions, or amplifications described herein may be included in the operations herein, either individually or in combination with any other feature described herein.

[0328] The foregoing description of methods and processes is provided as illustrative examples only and is not intended to require or imply that the steps of the various embodiments must be performed in the presented order. As those skilled in the art will understand, the order of steps in the above embodiments can be performed in any order. Words such as “after,” “then,” “next,” and similar terms are not intended to limit the order of steps; these words are merely used to guide the reader through the description of the method. Furthermore, any reference to singular claim elements, for example, using the articles “a,” “an,” or “the,” should not be construed as limiting the element to the singular and, in some cases, may be interpreted in the plural form.

[0329] As described above, and based on this disclosure, it will be appreciated that embodiments of this disclosure can be configured as systems, apparatuses, methods, mobile devices, back-end network devices, computer program products, other suitable devices, and combinations thereof. Therefore, embodiments may include a variety of apparatuses, including entirely hardware or any combination of software and hardware. Furthermore, embodiments may take the form of a computer program product on at least one non-transitory computer-readable storage medium having computer-readable program instructions (e.g., computer software) embodied in the storage medium. Any suitable computer-readable storage medium may be utilized, including non-transitory hard disks, CD-ROMs, flash memory, optical storage devices, or magnetic storage devices. It should be understood that any computer program instructions and / or other types of code described herein may be loaded onto the circuitry of a computer, processor, or other programmable device to produce a machine, such that the computer, processor, or other programmable circuitry executing the code on that machine forms means for implementing various functions (including those described herein). In some embodiments, features of this disclosure may include or be communicatively coupled to an application-specific integrated circuit (ASIC) configured to convert differential output voltages from one or more thermopiles (e.g., in a single-chip or two-chip configuration).

[0330] Although various embodiments based on the principles disclosed herein have been shown and described above, modifications can be made by those skilled in the art without departing from the teachings of this disclosure. The embodiments described herein are representative only and not intended to be limiting. Many variations, combinations, and modifications are possible and are within the scope of this disclosure. Alternative embodiments resulting from the merging, integration, and / or omission of features of one or more embodiments are also within the scope of this disclosure. Therefore, the scope of protection is not limited by the description given above, but is defined by the following claims, which include all equivalents of the subject matter of the claims. Each claim is incorporated into the specification as further disclosure, and the claims are embodiments of this disclosure. Furthermore, any of the foregoing advantages and features may relate to specific embodiments, but the application of such published claims should not be limited to methods and structures that achieve any or all of the above advantages or have any or all of the above features.

[0331] Furthermore, the section headings used herein are intended to align with or provide organizational clues for the recommendations of 37 C. FR § 1.77. These headings should not limit or characterize the disclosure set forth in any of the claims published in this disclosure. For example, the description of the technology in the “Background Art” section should not be construed as an admission that a particular technology is prior art to any disclosure in this disclosure. Nor should “Summary of the Invention” be considered a limiting characterization of the disclosure set forth in the published claims. Furthermore, any reference in this disclosure to the singular forms of “Disclosure” or “Simplification” should not be used to prove that there is only one novel point in this disclosure. Multiple embodiments of this disclosure may be set forth according to the limitations of the multiple claims published in this disclosure, and such claims accordingly define the disclosure protected by them and their equivalents. In all cases, the scope of these claims should be considered in accordance with the advantages of the claims themselves, and should not be limited by the headings set forth herein.

[0332] Furthermore, without departing from the scope of this disclosure, the systems, subsystems, apparatuses, techniques, and methods described and illustrated in various embodiments in a discrete or separate manner can be combined or integrated with other systems, modules, techniques, or methods. Other devices or components shown or discussed as being interconnected or communicating with each other can be indirectly interconnected through some intermediate devices or components, whether such interconnection is made electrically, mechanically, or otherwise. Other examples of variations, substitutions, and modifications that can be identified by those skilled in the art without departing from the scope of this disclosure are also provided.

[0333] Those skilled in the art to which these embodiments pertain will recognize numerous modifications and other embodiments of the disclosure set forth herein, which benefit from the teachings presented in the foregoing description and associated drawings. Although the drawings show only certain components of the apparatuses and systems described herein, various other components may be used in conjunction with the components and structures disclosed herein. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. For example, various elements or components may be combined, rearranged, or integrated into another system, or certain features may be omitted or not implemented. Furthermore, the steps in any of the methods described above may not necessarily occur in the order depicted in the drawings, and in some cases, one or more of the depicted steps may occur substantially simultaneously, or additional steps may be involved. Although specific terminology is used herein, it is used only in a general and descriptive sense and not for limiting purposes.

[0334] For the purpose of providing a comprehensive understanding, certain exemplary embodiments have been described; however, it will be understood by those skilled in the art that the systems, apparatuses and methods described herein can be adapted and modified to provide systems, apparatuses and methods for other suitable applications, and other additions and modifications can be made without departing from the scope of the systems, apparatuses and methods described herein.

[0335] The embodiments described herein have been specifically shown and described, but it should be understood that various changes in form and detail are possible. Unless otherwise specified, the illustrated embodiments are to be understood as providing exemplary features of different details of certain embodiments, and therefore, unless otherwise specified, the illustrated features, components, modules, and / or aspects may be otherwise combined, separated, interchanged, and / or rearranged without departing from the disclosed system or method. Furthermore, the shape and size of the components are also exemplary and, unless otherwise specified, may be changed without affecting the scope of the disclosure and the exemplary systems, apparatus, or methods of this disclosure.

[0336] As used herein, the terms “about” and “approximately” generally refer to ±10% of the stated value; for example, about 250 μm would include 225 μm to 275 μm, and about 1,000 μm would include 900 μm to 1,100 μm.

[0337] This document uses conventional terms from the fields of electrical engineering, chemical engineering, materials science and engineering, and computer science. These terms are known in the art and are provided only as non-limiting examples for convenience. Therefore, unless otherwise indicated, the interpretation of the corresponding terms in the claims is not limited to any particular definition. Consequently, the terms used in the claims should be given the broadest reasonable interpretation.

[0338] Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that any arrangement adapted to achieve the same purpose may replace the specific embodiments shown. Many modifications will be apparent to those skilled in the art. Therefore, this application is intended to cover any modifications or variations.

[0339] The above detailed description includes reference to the accompanying drawings, which form part of the detailed description. These drawings illustrate specific embodiments that can be practiced by way of example. These embodiments are also referred to herein as “examples.” Such examples may include elements other than those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors contemplate examples using any combination or arrangement of those elements (or one or more aspects thereof) shown or described relative to a particular example (or one or more aspects thereof) or relative to other examples (or one or more aspects thereof) shown or described herein.

[0340] All publications, patents, and patent documents mentioned in this document are incorporated herein by reference in their entirety, as if they were individually incorporated by reference. In the event of any inconsistency between the usage in this document and that of the documents incorporated by reference, the usage in the incorporated references shall be considered supplementary to the usage in this document; in the case of irreconcilable inconsistencies, the usage in this document shall prevail.

[0341] In this document, as is common in patent documents, the terms “a” or “an” are used to include one or more, and are not related to any other instance or use of “at least one” or “one or more”. In this document, unless otherwise specified, the term “or” is used to mean a non-exclusive “or”, such that “A or B” includes “A but not B,” “B but not A,” and “A and B.” In this document, the terms “comprising” and “in which” are used as common English equivalents to the corresponding terms “including” and “wherein.” Additionally, in the following claims, the terms “comprising” and “including” are open-ended, meaning that a system, apparatus, article of manufacture, or process that includes elements other than those listed after such terms in the claims is still considered to fall within the scope of the claims. Furthermore, in the following claims, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their objects.

[0342] The above description is intended to be exemplary and not restrictive. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used by someone of ordinary skill in the art upon reviewing the above description. A summary of the specification is provided to comply with the requirements of Section 1.72(b) of 37 C.FR to allow the reader to quickly determine the nature of the technical disclosure and to submit it in a manner understood not to construe or limit the scope or meaning of the claims.

[0343] In this specific embodiment, various features may be combined to simplify this disclosure. This should not be construed as an intention that any disclosed, unclaimed features are essential to any claim. Rather, the subject matter of the invention may include fewer than all the features of the specific disclosed embodiment. Therefore, the following claims are hereby incorporated into the specific embodiment, wherein each claim is itself a separate embodiment, and such embodiments are contemplated to be combined with each other in various combinations or arrangements. The scope of the embodiments should be determined with reference to the appended claims and the full scope of the equivalents conferred by such claims.

Claims

1. A flow sensor, comprising: A flow channel configured to convey fluid, the flow channel being disposed along a first axis; A heating element is disposed near the flow channel, wherein the heating element is configured to release a predetermined amount of heat energy, and the center of the heating element is disposed along a second axis that is at least substantially perpendicular to the first axis. One or more first thermal sensing elements, the one or more first thermal sensing elements being configured at a first distance from the center of the heating element along the first axis, wherein a change in a first voltage difference between the inlet and outlet of the one or more first thermal sensing elements indicates a temperature change at the one or more first thermal sensing elements; One or more second thermal sensing elements are configured at a second distance from the center of the heating element along the first axis, the second distance being greater than the first distance, wherein a change in a second voltage difference between the inlet and outlet of the one or more second thermal sensing elements indicates a temperature change at the one or more second thermal sensing elements. The flow sensor is configured to determine the fluid flow rate through the flow channel based on the correlation between the sum of the first voltage difference and the second voltage difference and the fluid flow rate through the flow channel. The one or more first thermal sensing elements and the one or more second thermal sensing elements are located upstream of the heating element. Or, wherein the one or more first thermal sensing elements and the one or more second thermal sensing elements are located downstream of the heating element, and The circuit is configured to at least: Determine the sum of the first voltage difference and the second voltage difference; as well as The sum of the first and second voltage differences is compared to a calibration curve that correlates multiple summed voltage differences with the fluid flow rate. The first distance is between 25µm and 75µm, and the second distance from the heating element is between 125µm and 175µm.

2. The flow sensor of claim 1, wherein the one or more first thermal sensing elements or the one or more second thermal sensing elements comprise at least one of the following: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple, or a thermopile.

3. The flow sensor of claim 1, wherein the one or more first thermal sensing elements are configured at a first distance from the center of the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel, wherein the one or more second thermal sensing elements are configured at a second distance from the center of the heating element in an upstream direction relative to the flow direction of the fluid in the flow channel, and wherein the flow sensor further comprises: One or more third thermal sensing elements, the one or more third thermal sensing elements being arranged at a first distance from the center of the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel; and One or more fourth thermal sensing elements are configured at a second distance from the center of the heating element in the downstream direction relative to the flow direction of the fluid in the flow channel.

4. The flow sensor according to claim 1, further comprising: A sensor component, the sensor component including a top surface and defining an inner cavity; and A membrane is disposed on a portion of the top surface of the sensor component, wherein one or more first thermal sensing elements and one or more second thermal sensing elements are disposed on or within the membrane. Each of the one or more first thermal sensing elements and the one or more second thermal sensing elements includes a first thermocouple material operably coupled to a thermocouple contact at a first end, and a second thermocouple material operably coupled to the thermocouple contact at the first end. The thermocouple contact is positioned at the first distance from the center of the heating element, and wherein the second end of the first thermocouple material and the second end of the second thermocouple material extend beyond the edge of the membrane disposed on or within the sensor component.

5. The flow sensor of claim 1, wherein the flow channel has a height or diameter between 1 µm and 500 µm, and is configured to measure flow rates between 0.1 mL / h and 1,000 mL / h.

6. The flow sensor of claim 1, wherein the heating element has a width between 5µm and 100µm, and wherein the heating element has a length between 50µm and 1,000µm.

7. The flow sensor of claim 1, wherein the one or more first thermal sensing elements are configured to be electrically coupled to the one or more second thermal sensing elements.

8. A method for measuring the flow rate of a fluid in a flow path, the method comprising: The heating element emits a known amount of heat energy, and the heating element is positioned substantially perpendicular to the flow path; A first current having a first voltage is provided to the inlet of a first thermal sensing element, the first thermal sensing element being spaced a first distance from the central longitudinal axis of the heating element; The first thermal sensing element is disposed within a membrane mounted on the top surface of the sensor component; A second current with a second voltage is provided to the inlet of the second thermal sensing element, the second thermal sensing element being spaced apart from the central longitudinal axis of the heating element by a second distance, the second distance being greater than the first distance, wherein the second thermal sensing element is disposed within a membrane mounted on the top surface of the sensor component; The first thermal sensing element and the second thermal sensing element are located upstream of the heating element. Alternatively, wherein the first thermal sensing element and the second thermal sensing element are located downstream of the heating element, and the outlet voltage at the respective outlets of the first thermal sensing element and the second thermal sensing element is measured, wherein the outlet voltage at the respective outlets of the first thermal sensing element and the second thermal sensing element indicates the fluid flow rate; Determine a first voltage difference between the inlet and the outlet of the first thermal sensing element and a second voltage difference between the inlet and the outlet of the second thermal sensing element; as well as The flow rate of the fluid in the flow path is determined based on the correlation between the sum of the first voltage difference and the second voltage difference and the flow rate of the fluid in the flow path; Sum the first voltage difference and the second voltage difference; as well as The sum of the first voltage difference and the second voltage difference is compared with a calibration curve, wherein the calibration curve correlates multiple summed voltage differences with multiple associated fluid flow rates to determine the flow rate of the fluid in the flow path.

9. A flow sensor, comprising: A flow top cover component that at least partially defines a flow channel, wherein the flow channel is configured to convey fluid therethrough and the flow channel is disposed substantially along a first axis; A sensor component, including a top surface and defining an inner cavity, wherein a flow top cover is operatively coupled to at least a portion of the top surface of the sensor component, the sensor component comprising: A membrane disposed on the top surface of the sensor component; A heating element disposed on or within the sensor component, the heating element being disposed along a second axis that is at least substantially perpendicular to the first axis; A first thermal sensing element is disposed on or inside the membrane along the second axis and spaced a first distance from the center of the heating element along a first direction, wherein a first output voltage can be measured at the outlet of the first thermal sensing element; A second thermal sensing element is disposed on or inside the membrane along the second axis and spaced a second distance from the center of the heating element in the first direction, the second distance being greater than the first distance, wherein a second output voltage can be measured at the outlet of the second thermal sensing element; A third thermal sensing element is disposed on or within the membrane along the second axis and spaced a first distance from the center of the heating element in a second direction opposite to the first direction, wherein a third output voltage can be measured at the outlet of the third thermal sensing element; and A fourth thermal sensing element is disposed on or within the membrane along the second axis and spaced a second distance from the center of the heating element along the second direction, wherein a fourth output voltage can be measured at the outlet of the fourth thermal sensing element. The voltage difference between the sum of the first and second output voltages and the sum of the third and fourth output voltages indicates the fluid flow rate through the flow channel.

10. The flow sensor of claim 9, wherein one or more of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element and the fourth thermal sensing element comprise at least one of the following: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple or a thermopile.

11. The flow sensor of claim 10, wherein each of the first thermal sensing element, the second thermal sensing element, the third thermal sensing element, and the fourth thermal sensing element comprises a first thermocouple material operatively coupled to a thermocouple contact at a first end, and a second thermocouple material operatively coupled to a thermocouple contact at the first end.

12. The flow sensor of claim 11, wherein the second end of the first thermocouple material is positioned at a first distance from the center of the heating element, wherein the second end of the second thermocouple material is positioned at a second distance from the center of the heating element, wherein the first distance is between 25 μm and 75 μm, and wherein the second distance is between 125 μm and 175 μm.

13. The flow sensor of claim 12, wherein the membrane comprises one or more first materials, and the sensor component comprises one or more second materials, wherein the one or more first materials are substantially thermally insulating and the one or more second materials are substantially thermally conductive.

14. A method for manufacturing a flow sensing device, the method comprising: A flow top cover component is provided that partially defines a flow path oriented along a first axis; A sensor component including a heating element is provided, wherein the sensor component includes a top surface and defines an inner cavity, the heating element is oriented substantially along a second axis substantially orthogonal to a first axis, the sensor component further including a first thermal sensing element and a second thermal sensing element, the first thermal sensing element being disposed at a first distance from the heating element along the first axis and the second thermal sensing element being disposed at a second distance from the heating element along the first axis. The flow top cover component is bonded to the first surface of the sensor component to form a flow channel therebetween. A film is disposed on a portion of the top surface of the sensor component, wherein the first thermal sensing element and the second thermal sensing element are disposed within the film; and The first thermal sensing element and the second thermal sensing element are located upstream of the heating element. Alternatively, the first thermal sensing element and the second thermal sensing element may be located downstream of the heating element. Provide a circuit configured to at least: The sum of a first voltage difference and a second voltage difference is determined, wherein the first voltage difference is determined between the inlet and outlet of the first thermal sensing element and the second voltage difference is determined between the inlet and outlet of the second thermal sensing element; as well as The sum of the first and second voltage differences is compared with a calibration curve, which is correlated with multiple summed voltage differences of the fluid flow rate in the flow channel.

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