Flow Sensing Device

Abstract

To provide a method, device, and computer program product associated with a flow sensing device.SOLUTION: An exemplary flow sensing device is a controller component in electronic communication with a flow sensing component, and includes a controller component configured to: monitor at least one flow sensing component output; detect an air bubble at a location adjacent to a surface of the flow sensing component based at least in part on the at least one flow sensing component output; and determine whether the air bubble satisfies a bubble condition that defines one or more predetermined characteristics.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Flow sensors can be used to measure the flow rate and / or volume 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 dispensing of a liquid or gas.

[0002] Such flow sensors suffer from technical challenges and limitations. Through exerted effort, ingenuity, and innovation, many of these identified problems have been resolved by developing solutions contained in embodiments of the present disclosure, many examples of which are described in detail herein. Summary of the Invention

[0003] Various embodiments of the present disclosure may provide an exemplary flow sensing device.

[0004] An exemplary flow sensing device may include a housing, a flow sensing component disposed at least partially within the housing, the flow sensing component configured to be in direct contact with the flow medium in a flow path of the flow sensing device, and a controller component in electronic communication with the flow sensing component, the controller component configured to monitor at least one flow sensing component output, detect an air bubble at a location adjacent to a surface of the flow sensing component based at least in part on the at least one flow sensing component output, and determine whether the air bubble satisfies an air bubble condition defining one or more predetermined characteristics.

[0005] In some embodiments, the controller component is further configured to perform generating a bubble indication in response to determining that the bubble satisfies the bubble condition.

[0006] In some embodiments, monitoring the at least one flow sensing component output includes determining whether the at least one sensing component output is less than a previous value and determining whether the output of the at least one sensing component is equal to a predetermined minimum value.

[0007] In some embodiments, the flow sensing device is positioned such that when the flow medium comes into direct contact with the flow sensing device, a void is formed adjacent to a surface of the flow sensing device, and at least one of the predetermined characteristics is associated with an air bubble that is bonded to the void.

[0008] In some embodiments, the flow sensing component comprises at least one heating element, a first flow sensing element positioned upstream relative to the at least one heating element, and a second flow sensing element positioned downstream relative to the at least one heating element.

[0009] In some embodiments, the flow sensing component comprises a sensing die. In some embodiments, the controller component is configured to determine whether the bubble meets the bubble condition by determining a first temperature output associated with the first flow sensing element, determining a second temperature output associated with the second flow sensing element, and comparing the first temperature output and the second temperature output.

[0010] In some embodiments, the controller component is further configured to, in response to detecting an air bubble, start a bubble residence timer, determine a minimum allowable residence time value, look up a maximum allowable residence time coefficient, and, in cases where the maximum allowable residence time value is less than the air bubble residence time value, generate an air bubble residence indication.

[0011] In some embodiments, the controller component is further configured to generate a second bubble residence indication in cases where the maximum allowable residence time value is less than a flow termination factor, hi some embodiments, the flow termination factor is determined based at least in part on an estimated long flow void length in the flow path representative of a flow termination scenario.

[0012] Some embodiments of the present disclosure provide a method that may include monitoring at least one flow sensing component output by a controller component in electronic communication with the flow sensing component, the flow sensing component being at least partially disposed within a housing of the flow sensing device, the flow sensing component being configured to directly contact a flow medium in a flow path of the flow sensing device, detecting, by the controller component, an air bubble at a location adjacent a surface of the flow sensing component based at least in part on the at least one flow sensing component output, and determining, by the controller component, whether the air bubble satisfies an air bubble condition defining one or more predetermined characteristics.

[0013] The foregoing exemplary summary, as well as examples of other exemplary objects and / or advantages of the present disclosure, and the manner in which they may be achieved, may be further described in the following detailed description and its accompanying drawings. [Brief explanation of the drawings]

[0014] The description of the illustrated embodiments may be read in conjunction with the accompanying drawings. Unless otherwise noted, it will be understood that for simplicity and clarity of illustration, components and elements shown in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the components or elements may be exaggerated relative to other components or elements unless otherwise noted. Embodiments incorporating the teachings of the present disclosure are shown and described in connection with the figures presented herein. [Figure 1] 1 illustrates a perspective view of an exemplary flow sensing device, according to an embodiment of the present disclosure. [Figure 2]1 illustrates a cross-sectional view of an exemplary flow sensing device, according to an embodiment of the present disclosure. [Figure 3A] 1 illustrates a cross-sectional view of an exemplary flow sensing device, according to an embodiment of the present disclosure. [Figure 3B] 1 illustrates a cross-sectional view of an exemplary flow sensing device, according to an embodiment of the present disclosure. [Figure 4] 1 illustrates a cross-sectional view of an exemplary flow sensing device, according to an embodiment of the present disclosure. [Figure 5] 1 illustrates an exemplary controller component in electronic communication with an exemplary device, according to various embodiments of the present disclosure. [Figure 6] 1 is a flowchart diagram illustrating exemplary operations according to various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Certain embodiments of the present disclosure will now be described in more detail below with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the present disclosure. Indeed, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0016] The phrases "in one embodiment," "according to one embodiment," "in some embodiments," and similar phrases generally mean that the particular feature, structure, or characteristic that follows the phrase may be included in at least one embodiment of the present disclosure, and may be included in more than one embodiment of the present disclosure (although such phrases do not necessarily refer to the same embodiment).

[0017] When the specification uses the words "may," "can," "could," "should," "would," "preferably," "possibly," "typically," "optionally," "for example," "in one embodiment," "in some embodiments," "in many cases," or "might" (or other such phrases) in reference to the inclusion or having of a certain component or feature, the particular component or feature is not required to be included or have the characteristic. Such component or feature may be optionally included or excluded in some embodiments.

[0018] As used herein, the words "example" or "exemplary" mean "serving as an example, instance, or illustration." Any embodiment described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0019] In this disclosure, the terms "electronically coupled," "electronically coupled," "electronically coupled," "communicating with," "in electronic communication with," or "connected" refer to two or more elements or components that are connected via wired and / or wireless means such that signals, electrical voltage / current, data, and / or information can be transmitted to and / or received from those elements or components.

[0020] The term "component" may refer to an article, device, or apparatus that may comprise one or more surfaces, portions, layers, and / or elements. For example, an example component may comprise one or more substrates that may provide an underlying layer for the component, may form part of a substrate, and / or may comprise one or more elements disposed on a substrate. In this disclosure, the term "element" may refer to an article, device, or apparatus that may provide one or more functions.

[0021] The term "flow sensing device" refers to an apparatus that can detect, measure, and / or identify the flow rate (including, but not limited to, linear flow rate, non-linear flow rate, mass flow rate, and / or volumetric flow rate) of one or more flow media. In this disclosure, the term "flow medium" refers to a substance (such as, but not limited to, a liquid substance and / or a gaseous substance).

[0022] The term "flow path" may refer to a passageway through which a flow medium may flow, traverse, or be transported. Exemplary flow paths of the present disclosure may be defined / formed by and / or comprise one or more channels. Exemplary channels may define multiple sidewalls. In various embodiments of the present disclosure, exemplary dimensions of exemplary cross-sections of exemplary flow paths / channels may range from a few microns to hundreds of microns in height and from tens of microns to thousands of microns in width. In various embodiments of the present disclosure, exemplary flow paths / channels may be 4500 microns wide and 1500 microns high to provide flow rates of up to 1000 milliliters per hour (mL / hr).

[0023] The term "laminar flow" may be characterized by particles of a flow medium following smooth paths in a flow path / channel with little or no mixing (i.e., high momentum diffusion and low momentum convection). In contrast, the term "turbulent flow" may be characterized by particles of a flow medium undergoing irregular fluctuations or mixing. In some embodiments, laminar flow in a flow sensing device may be achieved based on the flow rate of the flow medium. As described herein, embodiments of the present disclosure may be implemented in an infusion pump where the flow rate may be below a flow rate threshold (e.g., 0.02 milliliters per hour (mL / hr) to 0.5 mL / hr).

[0024] Flow sensing devices may be utilized in a variety of applications, including micropipettes, high-performance liquid chromatography (HPLC) applications, medical devices (e.g., drug delivery, infusion pumps, dialysis pumps), and the like. For example, an exemplary flow sensing device may be implemented in an invasive or non-invasive drug delivery system to detect, measure, and / or identify the flow rate of a flowable medium associated with the invasive or non-invasive drug delivery system. In such an example, an infusion pump may be implemented to deliver a substance (such as, but not limited to, a fluid, a medication, and / or a nutrient) into a patient's body in an invasive drug delivery system. The substance may need to be delivered in a controlled amount. Thus, an exemplary flow sensing device may be implemented in an infusion pump to detect, measure, and / or identify the flow rate of the substance that may be delivered to the patient. In various examples, the flow rate of the flowable medium may need to be accurately measured. Continuing from the infusion pump example above, the flow rate of the substance may need to be delivered at a slow rate based on the patient's condition and / or the patient's treatment. For example, the substance may need to be delivered at less than 5 milliliters per hour. If the flow rate is not measured accurately, the patient may be overdosed or underdosed, which may result in injury, injury, and / or death.

[0025] In some embodiments, a flow sensing device (e.g., a micro-electro-mechanical systems (MEMS) thermopile-based flow sensing device) can comprise a heating element and two temperature sensors (e.g., thermopiles), each positioned adjacent to a side of the heating element. In some examples, a first temperature sensor can be positioned upstream with respect to the flow, and a second temperature sensor can be positioned downstream with respect to the flow. The term downstream can refer to the position of a first component in a flow channel relative to a second component in the flow channel based at least in part on the direction of flow of the flow medium in the flow channel. For example, if the flow medium flows to component A and then to component B, component B is downstream with respect to component A. Similarly, the term upstream can refer to the position of a first component in a flow channel relative to a second component in the flow channel based at least in part on the direction of flow of the flow medium in the flow channel. For example, if the flow medium flows to component A and then to component B, component A is upstream with respect to component B. In various embodiments, the temperature distribution (i.e., ΔT or dT) or temperature difference between the first and second temperature sensors is calibrated using electronic signal processing circuitry to extract / determine flow information associated with the flow medium in the flow path / channel.

[0026] 1, a schematic diagram is provided depicting a cross-sectional view of an exemplary flow sensing device 100 in accordance with various embodiments of the present disclosure. As depicted in FIG. 1, the flow sensing device 100 comprises a housing 101 and flow sensing components 103 (e.g., a controller component, a sensing chip, a printed circuit board assembly (PCBA), etc.).

[0027] 1 , the housing 101 of the exemplary flow sensing device 100 may be or may comprise a tubular member configured to transport a flow medium from an inlet 102 of the flow sensing device 100 to an outlet 104 of the flow sensing device 100. In various embodiments, the flow sensing device 100 may form part of and / or be connected to an external flow path / channel (e.g., via a first tube connected to the inlet 102 and a second tube connected to the outlet 104) such that the flow medium can be transported therethrough. In various embodiments, the inlet 102 and the outlet 104 may define or comprise slide-on fittings, luer locks, swage-locks, etc. In various embodiments, the exemplary housing 101 may be or include plastic, a biodegradable material, polymethyl methacrylate (PMMA), cyclic olefin copolymer, polycarbonate, polystyrene, polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), liquid-crystal polymer (LCP), polyetherimide (PEI), epoxy, perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), combinations thereof, and the like.

[0028] As described above, the exemplary flow sensing device 100 includes a flow sensing component 103. In various examples, a surface of the exemplary housing 101 may be disposed adjacent to a surface of the flow sensing component 103. For example, as depicted in FIG. 1 , a bottom surface of the housing 101 of the flow sensing device 100 may be disposed adjacent to and / or attached to a top surface of the flow sensing component 103. In various embodiments, the flow sensing component 103 may be in electronic communication with one or more elements of the flow sensing device 100. By way of example, the exemplary flow sensing component 103 may be or include a sensing chip, a transducer, etc. Additionally, the flow sensing component 103 may include one or more additional elements, such as, but not limited to, one or more heating elements, temperature sensors, etc. The exemplary flow sensing component 103 may include a glass-reinforced epoxy laminate material (e.g., FR-4). In various embodiments, the exemplary flow sensing component 103 may include epoxy, ceramic, alumina, LCP, etc. In some embodiments, the sensing tip may be connected to another element of the flow sensing component using wire bonds, bump bonds, etc. The exemplary flow sensing component 103 may include a thick-film printed ceramic substrate, laminate, and / or other material. As depicted in FIG. 1 , the exemplary flow sensing component 103 includes one or more electronic components and / or pads thereon for connecting to other electronic components of the flow sensing device 100 and / or other equipment. In some examples, the flow sensing component 103 may include an application specific integrated circuit (ASIC) that may be attached to a surface of the flow sensing component 103, such as an ASIC electrically coupled to the flow sensing component 103 via wire bonds, bump bonds, electrical terminals, and / or any other suitable electrical connection. Additionally or alternatively, the exemplary flow sensing component 103 may include one or more conductive pads for engaging circuitry and / or electronic components for communication with a remote processor, etc.

[0029] While the above description provides an exemplary flow sensing device 100, it should be noted that the scope of the present disclosure is not limited to the above description. In some embodiments, the exemplary flow sensing device 100 according to the present disclosure may be in other forms. In some embodiments, the exemplary flow sensing device 100 may include one or more additional and / or alternative elements and / or may be structured / positioned differently than illustrated in FIG. 1 .

[0030] 2, a schematic diagram is provided depicting an exemplary flow sensing device 200 according to various embodiments of the present disclosure. As depicted in FIG. 2, the flow sensing device 200 comprises a housing 201 and flow sensing components 203 (e.g., a controller component, a sensing chip, a printed circuit board assembly (PCBA), etc.).

[0031] As depicted, the flow sensing device 200 comprises / defines a flow path / channel 202. The flow path / channel 202 may refer to a passage beginning at an inlet and ending at an outlet, through which a flow medium may enter, flow through, and exit the flow sensing device 200. The flow path / channel 202 may be or comprise, for example, without limitation, a pipe, a conduit, a tubular structure, or the like. The flow medium (e.g., liquid, gas, and / or air) may enter an inlet located on a first surface of the exemplary flow sensing device 200, travel through at least a portion of the flow path / channel 202, and exit the flow sensing device through an outlet located on another surface of the flow sensing device 200. In an invasive flow sensing device, the flow medium may directly contact a flow sensing component 203 (e.g., a thermal flow sensing chip) positioned within the flow path / channel 202 of the flow sensing device 200 such that the flow sensing component 203 can detect the flow rate of the flow medium.

[0032] 2 , as the flow medium or liquid flows through the flow path / channel 202 of the flow sensing device, it can contact at least a portion of the flow sensing component 203 (e.g., sensing tip) (in some examples, such that a sensing bridge or active area is in direct contact with the flow sensing component 203 (e.g., sensing tip)). In some examples, as the flow medium or liquid flows adjacent to at least one surface / edge of the flow sensing component 203 (e.g., sensing tip), localized disturbances / turbulence in the flow of the flow medium can be generated due to interaction between the flow sensing component 203 (e.g., sensing tip) and the flow medium or liquid. In some embodiments, the exemplary flow sensing component 203 (e.g., sensing tip) can include a protective coating or layer (e.g., a passivation layer, such as a silicon nitride passivation layer) that protects the flow sensing component 203 (e.g., sensing tip) and repels any flow medium or liquid. In some embodiments, as a flow medium or liquid flows across and / or over the flow sensing component 203, heat from a nearby heating element or heater may flow along with the liquid, creating an asymmetric temperature flow profile. In various examples, thin air gaps adjacent to the surface of the flow sensing component 203 may be tolerated, and the flow sensing device 200 may be appropriately calibrated to account for such air gaps. However, in instances where air gaps / gas bubbles are present in the flow medium (e.g., liquid), the flow sensing device 200 may generate erroneous outputs and fail to accurately detect the flow rate of the sample flow medium.

[0033] In different applications, the flow sensing component 203 (e.g., a sensing tip) may be or may comprise a sensing tip having hydrophobic (e.g., repels flow media / liquids) or hydrophilic (e.g., is wetted by flow media / liquids) properties. In some examples, as described above, when a liquid contacts an exemplary hydrophilic sensing tip surface, a thin air film may exist adjacent to the sensing tip surface due to the interaction between the liquid surface tension and the sensing tip surface energy. The presence of a gap / void (e.g., several microns to several hundred microns in height) above a flow sensing component such as a sensing tip may pose many technical challenges and limitations. For example, the size / height of the gap / void may depend on the amount of surface tension on the surface of the flow sensing component. In examples of invasive flow sensing devices, air films (e.g., air bubbles, gas bubbles, etc., used interchangeably herein) trapped in a flow medium (e.g., a liquid) moving adjacent to the flow sensing component may reduce the accuracy of measurements obtained using the flow sensing component and may adversely affect the sensitivity and / or resolution of the generated flow measurements. In some embodiments, the flow sensing component (e.g., sensing tip) may be treated to become more hydrophilic to improve wettability. However, the contact angle with the flow sensing component / sensing tip surface may be insufficient to achieve suitable wettability of the flow sensing component / sensing tip. Additionally, treating the flow sensing component / sensing tip may involve additional processing steps that may significantly increase the complexity and cost of fabrication / manufacturing.

[0034] 3A, a schematic diagram is provided depicting an exemplary flow sensing device 300A according to various embodiments of the present disclosure. As depicted in FIG. 3A, the flow sensing device 300A includes a housing 301A and flow sensing components 303A (e.g., a controller component, a sensing chip, a printed circuit board assembly (PCBA), etc.).

[0035] As depicted in FIG. 3A , the flow sensing device 300A includes / defines a flow path / channel 302A. The flow path / channel 302A may refer to a passage beginning at an inlet and ending at an outlet, through which a flow medium can enter, flow through, and exit the flow sensing device 300A. The flow medium (e.g., liquid and / or air) may enter an inlet on a first surface of the exemplary flow sensing device 300A, travel through at least a portion of the flow path / channel 302A, and exit the flow sensing device through an outlet on another surface of the flow sensing device 300A. As depicted in FIG. 3A , as the flow medium or liquid flows through the flow path / channel 302A of the flow sensing device 300A, it may contact at least a portion of the flow sensing component 303A (e.g., a sensing tip) (in some embodiments, such that a sensing bridge or active area is in direct contact with the flow sensing component 303A (e.g., a sensing tip)). In some embodiments, when a flow medium or liquid flows adjacent to at least one surface / edge of the flow sensing component 303A (e.g., sensing tip), localized disturbances / turbulence may be generated in the flow of the flow medium in the stream due to interaction between the flow sensing component 303A (e.g., sensing tip) and the flow medium or liquid.

[0036] As illustrated in FIG. 3A , in some embodiments, fluid located directly above the top surface of the flow sensing component 303A (e.g., the sensing chip) may be displaced (e.g., with a force equal to the surface tension of the sensing chip passivation layer), leaving behind a void 304A. In some embodiments, the normal force associated with edge-induced turbulence further increases the tensile force on the flow sensing component 303A (e.g., the sensing chip) surface to define the void 304A. The tensile force may be balanced / opposed by the normal force from the fluid column and the fluid flow pressure. Thus, the balance between the two forces may result in a particular thickness of the void 304A. In various embodiments, as long as the thickness of the void 304A remains relatively constant during the surface interaction, the flow measurements detected / produced using the flow sensing component 303A are accurate.

[0037] As further depicted in FIG. 3A, the flow medium may include a plurality of gas bubbles (as shown, at least a first gas bubble 306A, a second gas bubble 308A, and a third gas bubble 310A), each of which may flow through the flow path / channel 302A along with the flow medium.

[0038] 3B, another schematic diagram is provided depicting an exemplary flow sensing device 300B according to various embodiments of the present disclosure. The flow sensing device 300B may be similar to or identical to the flow sensing device 300A described above in connection with FIG. 3A. As depicted in FIG. 3B, the flow sensing device 300B includes a housing 301 and flow sensing components 303B (e.g., a controller component, a sensing chip, a printed circuit board assembly (PCBA), etc.).

[0039] As depicted in FIG. 3B , the flow sensing device 300B includes / defines a flow path / channel 302B. A flow path / channel 302B may refer to a passage beginning at an inlet and ending at an outlet, through which a flow medium can enter, flow through, and exit the flow sensing device 300B. A flow medium (e.g., liquid and / or air) may enter an inlet on a first surface of the exemplary flow sensing device 300B, travel through at least a portion of the flow path / channel 302B, and exit the flow sensing device through an outlet on another surface of the flow sensing device 300B. As depicted in FIG. 3B , as the flow medium or liquid flows through the flow path / channel 302B of the flow sensing device 300B, it may contact at least a portion of the flow sensing component 303B (e.g., a sensing tip) (in some embodiments, such that a sensing bridge or active area is in direct contact with the flow sensing component 303B (e.g., a sensing tip)). In some embodiments, when a flow medium or liquid flows adjacent to at least one surface / edge of the flow sensing component 303B (e.g., sensing tip), localized disturbances / turbulence may be generated in the flow of the flow medium in the stream due to interaction between the flow sensing component 303B (e.g., sensing tip) and the flow medium or liquid.

[0040] As depicted in FIG. 3B , the flow medium includes at least a first gas bubble 306B, a second gas bubble 308B, and a third gas bubble 310B. As further depicted in FIG. 3B , in addition to the void 304B located directly above the top surface of the flow sensing component 303B (e.g., the sensing chip), gas bubbles may be trapped above / with the void 304B. As depicted, the first gas bubble 306B is trapped adjacent to (e.g., coupled to, contacting, etc.) the void 304B, thereby increasing the overall size / thickness of the gap / void. In some embodiments, such coupling between the gas bubble and a prevalent void / air film on the flow sensing component / sensing chip can change the effective air film thickness and result in flow measurement errors. In some cases, the exemplary gas bubble may be retained adjacent to the void / air film for an extended period of time, thus interfering with flow measurement for an extended period of time. To solve these and other problems, techniques are needed to detect and provide an indication in response to unwanted air bubbles that may be present in a flow sensing device (e.g., a MEMS thermal flow sensor).

[0041] Various embodiments of the present disclosure provide exemplary methods, apparatuses, and systems. In some examples, a flow sensing device is provided. The flow sensing device may include a housing; a flow sensing component disposed at least partially within the housing, the flow sensing component configured to directly contact a flow medium in a flow path of the flow sensing device; and a controller component in electronic communication with the flow sensing component, the controller component configured to: monitor at least one flow sensing component output; detect an air bubble at a location adjacent to a surface of the flow sensing component based at least in part on the at least one flow sensing component output; and determine whether the air bubble satisfies an air bubble condition defining one or more predetermined characteristics. In some examples, the controller component is further configured to generate an air bubble indication in response to determining that the air bubble satisfies the air bubble condition. In some examples, monitoring the at least one flow sensing component output includes determining whether the at least one sensing component output is less than a previous value and determining whether an output of the at least one sensing component is equal to a predetermined minimum value. In some embodiments, the flow sensing device is positioned such that when the flow medium directly contacts the flow sensing device, a void is formed adjacent a surface of the flow sensing device, and at least one of the predetermined characteristics is associated with a bubble bonded to the void. In some embodiments, the flow sensing component comprises at least one heating element, a first flow sensing element positioned upstream relative to the at least one heating element, and a second flow sensing element positioned downstream relative to the at least one heating element. In some embodiments, the flow sensing component comprises a sensing tip. In some embodiments, the controller component is configured to determine whether the bubble meets the bubble condition by determining a first temperature output associated with the first flow sensing element, determining a second temperature output associated with the second flow sensing element, and comparing the first temperature output and the second temperature output.In some embodiments, the controller component is further configured to: start a bubble residence timer in response to detecting an air bubble; determine a minimum allowable residence time value; retrieve a maximum allowable residence time factor; and generate a bubble residence indication in the event that the maximum allowable residence time value is less than the bubble residence time value. In some embodiments, the controller component is further configured to generate a second bubble residence indication in the event that the maximum allowable residence time value is less than the flow termination factor. In some embodiments, the flow termination factor is determined based at least in part on an estimated long flow void length in the flow path representative of a flow termination scenario.

[0042] Some embodiments of the present disclosure provide a method. The method may include monitoring at least one flow sensing component output by a controller component in electronic communication with the flow sensing component, the flow sensing component being at least partially disposed within a housing of the flow sensing device, the flow sensing component being configured to directly contact a flow medium in a flow path of the flow sensing device; detecting, by the controller component, an air bubble at a location adjacent to a surface of the flow sensing component based at least in part on the at least one flow sensing component output; and determining, by the controller component, whether the air bubble satisfies an air bubble condition defining one or more predetermined characteristics. In some examples, the method includes generating, by the controller component, an air bubble indication in response to determining that the air bubble satisfies the air bubble condition. In some examples, monitoring the at least one flow sensing component output includes determining, by the controller component, whether the at least one sensing component output is less than a previous value; and determining, by the controller component, whether an output of the at least one sensing component is equal to a predetermined minimum value. In some embodiments, the flow sensing device is positioned such that when the flow medium directly contacts the flow sensing device, a void is formed adjacent a surface of the flow sensing device, and at least one of the predetermined characteristics is associated with a bubble bonded to the void. In some embodiments, the flow sensing component comprises at least one heating element, a first flow sensing element positioned upstream relative to the at least one heating element, and a second flow sensing element positioned downstream relative to the at least one heating element. In some embodiments, the flow sensing component comprises a sensing tip. In some embodiments, determining whether the bubble satisfies the bubble condition further includes determining, by a controller component, a first temperature output associated with the first flow sensing element, determining, by the controller component, a second temperature output associated with the second flow sensing element, and comparing, by the controller component, the first temperature output and the second temperature output.In some embodiments, the method includes starting, by a controller component, a bubble residence timer in response to detecting an air bubble, determining, by the controller component, a minimum allowable residence time value, retrieving, by the controller component, a maximum allowable residence time coefficient, and generating, by the controller component, a bubble residence indication in the event that the maximum allowable residence time value is less than the bubble residence time value. In some embodiments, the method includes generating, by the controller component, a second bubble residence indication in the event that the maximum allowable residence time value is less than the flow termination coefficient. In some embodiments, the flow termination coefficient is determined based at least in part on an estimated long flow void length in the flow path representative of a flow termination scenario.

[0043] 4, a schematic diagram is provided depicting a portion of an exemplary flow sensing device 400 in accordance with various embodiments of the present disclosure. In particular, as depicted, the exemplary flow sensing device 400 includes a flow sensing component 402 (e.g., a sensing chip). As illustrated, the flow sensing component 402 includes a heating element 403, a first flow sensing element 405, and a second flow sensing element 407. The flow sensing device 400 may be similar to or identical to the flow sensing devices 300A and 300B described above in connection with FIGS. 3A and 3B.

[0044] As depicted, the flow sensing device 400 defines a housing 401 or other enclosure configured to at least partially support one or more of a first flow sensing element 405, a second flow sensing element 407, and / or a heating element 403. The first flow sensing element 405, the second flow sensing element 407, and the heating element 403 may be in thermal engagement with a flow medium disposed within at least a portion of the flow sensing device 400. As shown, the flow sensing device 400 comprises a tubular member configured to transport a flow medium therethrough (e.g., from an inlet to an outlet of the flow sensing device 400). In various embodiments, the flow sensing device 400 may form a part of and / or be connected to an external flow path / channel, such that the flow medium can be transported through the external flow path / channel.

[0045] An exemplary gas bubble may propagate in a particular direction through the exemplary flow sensing device 400. As depicted, the gas bubble may propagate through the exemplary flow sensing device along a flow path 404. As the gas bubble moves through the flow sensing device 400, the first flow sensing element 405 and / or the second flow sensing element 407 may detect a change in temperature proximate the respective first and second flow sensing elements 405 and 407 (e.g., temperature sensors / thermopiles) due to changes in thermal conductivity within the exemplary flow sensing device 400.

[0046] As depicted in FIG. 4 , the exemplary flow sensing device 400 / flow sensing component 402 includes a heating element 403. In various examples, the heating element 403 may include any heat source configured to output thermal energy to heat or otherwise warm a flow medium within the flow sensing device 400 proximate the heating element 403. As an example, the heating element may include a resistive heating element in which passing an electric current through a resistor generates heat. Although described herein with reference to a resistive heating element 403, the present disclosure contemplates that any heating element (e.g., radiator, film heater, conduction heater, convection heater, etc.) may be used to generate a thermal output (e.g., generate heat). In various embodiments, the flow sensing device 400 further includes a controller / heating control circuitry operative to maintain and / or control the thermal output of the heating element 403. For example, the heating element 403 may include a coil, a ribbon (including, but not limited to, a straight ribbon, a corrugated ribbon), a plate, a wire strip, and / or a layer that may be connected to a power source. In some embodiments, the heating element 403 may include various geometric shapes, including, but not limited to, a serpentine, a serpentine with rounded corners, an S-shape, an S-shape with rounded corners, a double helix, a double helix with rounded corners, a double helix with irregular spacing, a flat plate with a square hole in the center, a circle, a drive wheel, an oval, a honeycomb, etc. When a power source is turned on, an electric current may flow through the coils, ribbons, plates, wire strips, and / or layers, which may then convert electrical energy into thermal energy.

[0047] The exemplary heating element 403 may be or include a high temperature coefficient of resistance (TCR) material (e.g., Pt, NiFe, doped silicon / polysilicon, PtSi and other silicides, W, AlN, WN, etc.). In some embodiments, the exemplary heating element 403 may include a nickel-based and / or iron-based material. For example, the heating element 403 may include one or more metallic materials, such as a nickel-iron (NiFe) alloy, which may provide a high temperature coefficient of electrical resistance. For example, the heating element 403 may include a Permalloy that is 81% nickel (Ni) and 19% iron (Fe). Additionally or alternatively, the heating element 403 may include 60% Ni and 40% Fe. In some embodiments, the heating element 403 may include platinum, for example, in the form of a thin film heater due to its high temperature coefficient of resistance (TCR). In some embodiments, copper alloys with low thermal conductivity, such as alloys, may also be used for the heating element 403.

[0048] In some examples, the example controller / heating control circuitry may operate to maintain a substantially constant (e.g., within applicable tolerances) heat output of the heating element 403. Stated another way, in some examples, the flow sensing device 400 may use a heating element 403 having a substantially constant heat output so as to stabilize the temperature data detected / generated by the first flow sensing element 405 and the second flow sensing element 407. In various embodiments, the controller may be co-located with the flow sensing device 400 or may be remote from the flow sensing device 400.

[0049] As described above and depicted in FIG. 4 , the exemplary flow sensing device 400 / flow sensing component 402 includes a first flow sensing element 405 (e.g., a first temperature sensor) and a second flow sensing element 407 (e.g., a second temperature sensor). In various examples, the first flow sensing element 405 may be configured to generate a first temperature data / output. As depicted, the first flow sensing element 405 may be in thermal engagement with at least a portion of the flow sensing device 400 (e.g., in thermal engagement with a flow medium within the flow sensing device 400) to determine a temperature within the flow sensing device 400 proximate the first flow sensing element 405. In some embodiments, the first flow sensing element 405 may be positioned upstream (e.g., with respect to the flow path 404) of the heating element 403 and the second flow sensing element 407. As examples, the first flow sensing element 405 may include a thermocouple, a positive temperature coefficient (PTC) thermistor, a negative temperature coefficient (NTC) thermistor, a p-n junction, a resistor, etc. configured to determine the temperature of the fluid proximate the first flow sensing element 405. While illustrated with a single first flow sensing element 405, the present disclosure contemplates that the first flow sensing element 405 may further comprise a pair of offset thermopiles configured, alone or in combination, to generate first temperature data. In other words, while this specification is described with reference to a single first flow sensing element 405 for convenience of description, the present disclosure contemplates that the techniques herein may be applicable to any number of first sensing elements / temperature sensors 405 positioned at any location relative to the flow sensing device 400.

[0050] 4, the flow sensing device 400 includes a second flow sensing element 407 that may be configured to generate a second temperature data / output. As shown, the second flow sensing element 407 may be thermally engaged with the flow sensing device 400 (e.g., may be thermally engaged with the flow medium within the flow sensing device 400) to determine a temperature within the flow sensing device 400 proximate the second flow sensing element 407. In some embodiments, the second flow sensing element 407 may be positioned downstream (e.g., with respect to the flow path 404) of the heating element 403 and the first flow sensing element 405. As examples, the second flow sensing element 407 may also include a thermocouple, a positive temperature coefficient (PTC) thermistor, a negative temperature coefficient (NTC) thermistor, a p-n junction, a resistor, etc. configured to determine a temperature of the fluid proximate the second flow sensing element 407. While illustrated with a single second flow sensing element 407, the present disclosure contemplates that the second flow sensing element 407 may further comprise a pair of offset thermopiles configured, alone or in combination, to generate second temperature data. In other words, while described herein with reference to a single second flow sensing element 407 for convenience of description, the present disclosure contemplates that the techniques herein may be applicable to any number of second flow sensing elements 407 / temperature sensors positioned in any location relative to the flow sensing device 400.

[0051] In some exemplary embodiments, the first flow sensing element 405 and / or the second flow sensing element 407 (or their equivalent functionality) may be positioned on the heating element 403. Stated differently, generating temperature data as described herein may, in some embodiments, refer to temperature data generated near or on the heating element 403. As an example, as a bubble / gas bubble passes near or across the heating element 403, the resistance of the heating element 403 may also change, at least in part, due to the difference in heat capacity and thermal conductivity between gas and liquid as described herein. As an exemplary gas bubble moves over the heating element 403 (e.g., a resistive heater), the temperature of the heating element 403 may increase, and the resistance of the heating element 403 may change based on the temperature coefficient of resistance of the material of the heating element 403. In some examples, a flow medium may move through a sensing region that may comprise the heating element 403, the first flow sensing element 405, and the second flow sensing element 407. For example, the first flow sensing element 405 is positioned upstream relative to the heating element 403. The second flow sensing element 407 is positioned downstream relative to the heating element 403. Thus, the first flow sensing element 405 may detect a first temperature of the flowable medium. The flowable medium may then be heated by the heating element 403, which may increase the temperature of the flowable medium by a predetermined amount. The second flow sensing element 407 may then detect a second temperature of the flowable medium. As the flow rate of the flowable medium increases, more heat may be lost as the flowable medium moves from the heating element 403 to the second flow sensing element 407. By comparing the difference between the first temperature and the second temperature to a predetermined amount, the flow rate of the flowable medium may be calculated / determined.

[0052] While the above description provides several examples of flow sensing elements / temperature sensors, it should be noted that the scope of the present disclosure is not limited to the above description. In some examples, the exemplary temperature sensor 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, the exemplary temperature sensor may include at least one temperature sensing circuit, such as, but not limited to, a resistor in a Wheatstone bridge circuit, or a temperature sensing diode. In an example of a Wheatstone bridge circuit, two resistive branches may be provided, each of which may include two resistive elements. Because temperature may affect the electrical resistance of the resistive elements, the exemplary temperature sensor may detect, measure, and / or identify the resistance change between the two resistive branches to determine the corresponding thermal energy.

[0053] While the above description provides an example flow sensing device 400, it should be noted that the scope of the present disclosure is not limited to the above description. In some embodiments, the example flow sensing device 400 according to the present disclosure may be in other forms. In some embodiments, the example flow sensing device 400 may include one or more additional and / or alternative elements and / or may be structured / positioned differently than illustrated in FIG. 4 . For example, the example flow sensing component may include fewer than two or more than two temperature sensors.

[0054] In some examples, the distance that a temperature sensor is spaced from the heating element can be selected to achieve acceptable accuracy of flow measurement over a wide range of acceptable flow rates and / or for a desired range of flow rates (e.g., low flow rates between about 1 μL / hr and about 10,000 μL / hr). In some embodiments, the number of temperature sensors can also be selected to achieve accuracy of flow measurement for a desired flow rate range. In some examples, using only a single temperature sensor can lead to gradually decreasing accuracy or precision at some flow rates, such as low flow rates. In some examples, using two temperature sensors spaced at different distances from the heating element can lead to increased accuracy, such as at low flow rates. Without wishing to be bound by any particular theory, increased accuracy or precision, such as at low flow rates, can be due to the difference between the peak accuracy for a closer temperature sensor and the peak accuracy for a more distant temperature sensor. In some examples, a closer temperature sensor may be better suited for accurate and / or precise measurement of higher flow rates because a higher flow rate of the medium can increase the heat sinking capability of the medium in the flow path of an exemplary flow sensing device. In some embodiments, the additional temperature sensor may be better suited for accurate and / or precise measurement of lower flow rates because a lower flow rate of the medium may reduce the heat sinking capability of the medium and differences in temperature may be more easily detected by the additionally positioned temperature sensor.

[0055] In some examples, when a temperature sensor may comprise a thermopile made up of multiple thermocouples, it may be useful to use more thermocouples in the thermopile because using more thermocouples may increase the sensitivity of the thermopile to temperature changes, which may increase the sensitivity of the flow sensor. In some examples, for example, for digital sensors, this may improve the accuracy of the number of bits representing the measured voltage value.

[0056] While the above description provides some examples of temperature sensors, it should be noted that the scope of the present disclosure is not limited to the above description. In some examples, an exemplary temperature sensor 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, an exemplary temperature sensor may include at least one temperature sensing circuit, such as, but not limited to, a resistor in a Wheatstone bridge circuit, or a temperature sensing diode.

[0057] In some embodiments, the temperature sensor may be located in a layer of the sensor component separate from the layer in which the heating element is located. In some embodiments, the separate layer of the sensor component comprising the temperature sensor may comprise one or more suitable materials, including but not limited to silicon nitride, silicon oxide, silicon oxynitride, polymer, or other electrically insulating thin film. In some embodiments, the separate layer of the flow sensing component comprising the temperature sensor may be an encapsulation layer that may protect the temperature sensor. In some embodiments, the encapsulation layer may be electrically insulating.

[0058] In some embodiments, the temperature sensor may be electronically coupled to one or more other elements (e.g., power supply, processor) based on techniques such as, but not limited to, through-glass vias (TGVs), through-silicon vias (TSVs), and / or aerosol or inkjet printing. Additionally or alternatively, the temperature sensor may be electronically coupled to one or more other elements through other means.

[0059] 5, a schematic diagram depicts an example controller component 500 of an example device in electronic communication with various other components, in accordance with various embodiments of the present disclosure. As shown, the controller component 500 comprises a processing circuit 501, a communications module 503, an input / output module 505, a memory 507, and / or other components configured to perform various operations, procedures, functions, etc., described herein.

[0060] As shown, controller component 500 (e.g., processing circuit 501, communications module 503, input / output module 505, and memory 507) is electrically coupled to and / or in electronic communication with flow sensing component 509. As depicted, flow sensing component 509 can exchange (e.g., transmit and receive) data with processing circuit 501 of controller component 500.

[0061] The processing circuit 501 may be implemented as a variety of devices including, for example, one or more microprocessors with digital signal processors, one or more processors without digital signal processors, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuits, one or more computers, and various other processing elements (including integrated circuits such as ASICs or FPGAs, or some combination thereof). In some embodiments, the processing circuit 501 may comprise one or more processors. In an exemplary embodiment, the processing circuit 501 is configured to execute instructions stored in memory 507 or accessible by the processing circuit 501. When executed by the processing circuit 501, these instructions may enable the controller component 500 to perform one or more of the functions as described herein. Whether configured by hardware, firmware / software methods, or a combination thereof, the processing circuit 501, when correspondingly configured, may comprise an entity capable of performing operations according to embodiments of the present invention. Thus, for example, when processing circuitry 501 is implemented as an ASIC, FPGA, etc., processing circuitry 501 may comprise hardware that is specially configured to perform one or more operations described herein. Alternatively, as another example, when processing circuitry 501 is implemented as an actuator of instructions (such as may be stored in memory 507), the instructions may specifically configure processing circuitry 501 to execute one or more algorithms and operations described herein, such as those described with reference to FIG.

[0062] Memory 507 may comprise, for example, volatile memory, non-volatile memory, or some combination thereof. While illustrated as a single memory in FIG. 5, memory 507 may comprise multiple memory components. In various embodiments, memory 507 may comprise, for example, a hard disk drive, random access memory, cache memory, flash memory, a Compact Disc Read-Only Memory (CD-ROM), a Digital Versatile Disk Read-Only Memory (DVD-ROM), an optical disk, a circuit configured to store information, or some combination thereof. Memory 507 may be configured to store information, data, application programs, instructions, etc. to enable controller component 500 to perform various functions in accordance with embodiments of the present disclosure. For example, in at least some embodiments, memory 507 is configured to cache input data for processing by processing circuit 501. Additionally or alternatively, in at least some embodiments, memory 507 is configured to store program instructions for execution by processing circuit 501. The memory 507 may store information in the form of static and / or dynamic information, which may be stored and / or used by the controller component 500 when functions are performed.

[0063] The communications module 503 may be implemented as any device included in a circuit, hardware, a computer program product, or a combination thereof, configured to receive and / or transmit data from / to another component or device. The computer program product includes computer-readable program instructions stored on a computer-readable medium (e.g., memory 507) and executed by the controller component 500 (e.g., processing circuit 501). In some embodiments, the communications module 503 (as well as other components described herein) may be at least partially implemented as or otherwise controlled by the processing circuit 501. In this regard, the communications module 503 may communicate with the processing circuit 501, for example, via a bus. The communications module 503 may comprise, for example, an antenna, a transmitter, a receiver, a transceiver, a network interface card, and / or supporting hardware and / or firmware / software, and is used to establish communication with another device. The communications module 503 may be configured to receive and / or transmit any data that may be stored by the memory 507 by using any protocol that may be used for communication between devices. The communications module 503 may additionally or alternatively communicate with the memory 507, the input / output module 505, and / or any other components of the controller component 500, for example, via a bus.

[0064] In some embodiments, the controller component 500 may include an input / output module 505. The input / output module 505 may communicate with the processing circuit 501 to receive commands input by a user and / or provide audio, visual, mechanical, or other output to the user. Accordingly, the input / output module 505 may include supporting devices such as a keyboard, a mouse, a display, a touchscreen display, and / or other input / output mechanisms. Alternatively, at least some aspects of the input / output module 505 may be implemented on a device used by a user to communicate with the controller component 500. The input / output module 505 may communicate with the memory 507, the communications module 503, and / or any other components, for example, via a bus. One or more input / output modules and / or other components may be included in the controller component 500.

[0065] For example, the flow sensing component 509 may be similar to the flow sensing component 402 described above with respect to Figure 4. For example, the flow sensing component 509 may generate a flow rate indication and transmit the flow rate indication to the processing circuit 501.

[0066] Referring now to FIG. 6, a flowchart illustrating exemplary operations 600 according to various embodiments of the present disclosure is provided.

[0067] In some examples, method 600 may be performed by a processing circuit (e.g., without limitation, an application specific integrated circuit (ASIC), a central processing unit (CPU)). In some examples, the processing circuit may be electrically coupled to and / or in electronic communication with other circuitry of the exemplary device, such as, without limitation, a wettable flow sensing component, a dehumidifier component, gas detection, memory (e.g., a random access memory (RAM) for storing computer program instructions), and / or display circuitry (for rendering readings on a display).

[0068] In some examples, one or more of the procedures described in Figure 6 may be embodied by computer program instructions that may be stored by a memory (e.g., non-transitory memory) and executed by a processing circuit (e.g., a processor) of a system employing embodiments of the present disclosure. These computer program instructions may direct the system to function in a particular manner, such that a product may be manufactured according to the instructions stored in the memory circuit, and execution thereof may implement the functions specified in the steps / acts of the flow diagram. Additionally, the system may include one or more other circuits. The various circuits of the system may be electronically coupled between each other to transmit and / or receive energy, data, and / or information.

[0069] In some examples, embodiments may take the form of a computer program product on a non-transitory computer-readable storage medium storing computer-readable program instructions (e.g., computer software). Any suitable computer-readable storage medium may be utilized, including a non-transitory hard disk, a CD-ROM, a flash memory, an optical storage device, or a magnetic storage device.

[0070] As described above, in various embodiments, the presence of a thin air film on the flow sensing component (e.g., the sensing chip) due to the degree of surface hydrophobicity or hydrophilicity can result in a thin boundary layer that reduces flow friction against the flowing medium and provides a predictable thermal interface for the flow sensing component (e.g., a sensing component, heating element, temperature sensor, including a thermopile, etc., that may be disposed on the MEMS flow sensing chip). Under these conditions, the flow sensing device can be calibrated for a specific flow range. Any change in the air film thickness can induce flow measurement errors. For example, when air / gas bubbles in the flowing medium (e.g., a liquid) pass over the flow sensing component (e.g., the sensing chip), the thermal conductivity can drop sharply, resulting in a decrease in the sensing component output (e.g., the thermopile output). In some examples, the signal difference (e.g., dT) between the upstream and downstream sensing components can be close to zero. Processing of such a signal can be used to detect the presence of air / gas bubbles in the flow sensing device flow path and trigger the generation of a control instruction / alert. In various embodiments, the algorithm may be implemented via an electronic controller with input from a flow sensing component (e.g., a thermopile or temperature sensor) using pre-set / stored parameters to identify various conditions, as described in more detail below. For example, the flow sensing device may be configured to detect an air bubble adjacent to a surface of the flow sensing component based at least in part on the flow sensing component output and determine whether the air bubble meets air bubble conditions that define one or more predetermined characteristics.

[0071] The exemplary method 600 begins at step / action 601. In step / action 601, a processing circuit (such as, but not limited to, the processing circuit 501 of the controller component 500 illustrated in connection with FIG. 5, described above) monitors one or more sensing component outputs (e.g., thermopile outputs). For example, the processing circuit may monitor a first sensing element output and a second sensing element output. The first sensing component and the second sensing component may be similar or identical to the first flow sensing element 405 and the second flow sensing element 407, described above in connection with FIG. 4. In particular, the first flow sensing element 405 and the second flow sensing element 407 may be positioned upstream and downstream, respectively, with respect to a heating element (e.g., heating element 403). The processing circuit may, for example, monitor a temperature range from a prevailing value to a predetermined minimum value ("T"). low ") and identify instances where the temperature distribution (dT) (e.g., between the two sensing elements) is close to zero. In instances where the above conditions are met, the processing circuitry may determine that an air / gas bubble is present in the flow path of the flow sensing device and adjacent to (e.g., on, near, etc.) the flow sensing component (e.g., the sensing tip).

[0072] In some embodiments, as described below, the processing circuitry detects whether (i) the flow sensing component / thermopile output voltage is lower than its previous value, and (ii) the flow sensing component / thermopile output voltage is lower than a predetermined minimum value (e.g., "T low "), and (iii) determining that a bubble passage condition exists based at least in part on detecting that the flow sensing component / thermopile output voltage (e.g., dT) variation meets a threshold (e.g., close to 0 or 0.01 millivolts (mV)).

[0073] Following step / action 601, method 600 proceeds to step / action 603. At step / action 603, in some embodiments, the processing circuit determines whether at least one flow sensing component output is less than a previous value.

[0074] Following step / action 603, method 600 proceeds to step / action 605. At step / action 605, in some embodiments, the processing circuit determines whether at least one flow sensing component output is equal to a predetermined minimum value.

[0075] Following step / action 605, method 600 proceeds to step / action 607. At step / action 607, in some embodiments, the processing circuit determines whether at least one flow sensing component output (e.g., dT) variation meets a threshold value (e.g., equal to 0.01 mV).

[0076] In various embodiments, the processing circuit may sequentially determine (e.g., check) whether at least one sensing component output changes from a typical value to a new lower value to determine whether there is flow medium disposed in the flow path of the flow sensing device. For example, if at least one flow sensing component output changes from a predetermined minimum value (e.g., "T low ") or within a predetermined minimum range, the processing circuit may determine that there is no flow medium disposed within the flow sensing device (i.e., an empty tube or no fluid condition). As another example, low contains the difference between the upstream and downstream temperature sensor outputs, which may be a fraction of a degree Celsius (e.g., 0.1 C, and the corresponding voltage difference may be equal to 0.01 mV for a given thermopile stack).

[0077] Following step / action 607, method 600 proceeds to step / action 609. At step / action 609, in response to determining or identifying an air bubble condition (e.g., an air bubble is present or passing) based at least in part on the preceding step / action, the processing circuitry starts an air bubble dwell timer (e.g., "t d For example, in response to detecting an air bubble, the processing circuitry may trigger the activation of a timer or timing mechanism to measure a period of time associated with the detected air / gas bubble.

[0078] Following step / action 609, method 600 proceeds to step / action 611. Further at step / action 611, in response to determining or identifying an air bubble condition, the processing circuit generates (e.g., transmits, sends, triggers, etc.) an air bubble presence indication (e.g., an alert regarding the presence of an air / gas bubble adjacent to, on, near, or near the flow sensing component).

[0079] Following step / operation 611, method 600 proceeds to step / operation 613. At step / operation 613, the processing circuit determines a minimum acceptable residence time value for the detected air / gas bubble. For example, the processing circuit may determine the minimum acceptable residence time value based at least in part on the previous flow rate value and the dimensions (e.g., width) of the flow sensing component (e.g., sensing tip). The minimum acceptable residence time value may define the period of time that the air / gas bubble is allowed to remain suspended while passing with the flow medium. For example, the processing circuit may determine the minimum acceptable residence time "tpd" using the following formula: tpd=sense die width / flow rate During the ceremony, Sensing tip width = sensing tip width parallel to the flow direction (e.g., 1.064 mm); Flow rate = typical measurement from the sensor.

[0080] Following step / action 613, method 600 proceeds to step / action 615. At step / action 615, the processing circuitry retrieves (e.g., obtains, fetches, etc.) a minimum allowable residence time coefficient (e.g., "S") from a set preset value according to the calculated residence time. In some embodiments, the processing circuitry determines that the allowable residence time coefficient "S" is a preset value that is determined based at least in part on the detected / general flow rate of the flow medium.

[0081] In some embodiments, the acceptable residence time factor "S" is determined by the linear regression equation over the range t pd The value of "S" can be determined by using the following formula: S=A * tpd+B* Lbubble+C During the ceremony, tpd = minimum allowable residence time for a given flow rate; L bubble = foam length, A, B, and C are regression coefficients.

[0082] In some embodiments, the value of S can be configured based on the particular application (flow range). For example, a given application, such as infusion pump flow measurement, can include performing factory testing to determine S, which can be a preset value. One such value can be 10 for flow rates of 1 to 1000 mL / hr, for bubble lengths ranging from 0.5 mm to 50 mm.

[0083] Following step / action 615, method 600 proceeds to step / action 617. At step / action 617, the processing circuitry determines a maximum allowable dwell time value (e.g., "t md In some embodiments, the processing circuit determines the maximum allowable dwell time value using the following equation: t md =S * t pd During the ceremony, S = minimum allowable residence time factor, t md = Maximum allowable dwell time value.

[0084] Following step / action 617, method 600 proceeds to step / action 619. At step / action 619, the processing circuit determines whether the maximum allowable dwell time value is greater than the current bubble dwell timer value (e.g., t d ) or less. In other words, the processing circuitry determines whether t md <t d Determine whether it is.

[0085] Following step / action 619, method 600 proceeds to step / action 621. At step / action 621, the maximum allowed residence time value is greater than the current bubble residence timer value (i.e., t md >t dIn some instances, the processing circuit determines that an air bubble is currently trapped / held adjacent to, on, or above the flow sensing component (e.g., the sensing tip) for a period of time that meets or exceeds the allowable dwell time value for the given flow rate. In such instances, at step / operation 621, the processing circuit generates a first air bubble dwell indication. However, in instances where the processing circuit determines that the maximum allowable dwell time value is lower than the current air bubble dwell timer value, method 600 proceeds to step / operation 627.

[0086] Following step / action 621, method 600 proceeds to step / action 623. At step / action 623, to distinguish between a bubble retention condition and an end-of-flow condition / scenario, the processing circuitry calculates a maximum allowable retention time value ("t md ") is less than a flow termination factor "EF." In some embodiments, the flow termination factor is determined based at least in part on an estimated long flow void length in a flow path representative of the flow termination scenario. In some examples, the flow void length may be 30 centimeters (cm) long.

[0087] In some embodiments, the flow termination factor "EF" is determined by the linear regression equation for the range t pd The flow termination factor "EF" can be determined by using the following formula: EF=D * tpd+E * Lflow voids+F During the ceremony, tpd = minimum allowable residence time for a given flow rate; L flow voids = foam length, D, E, and F are regression coefficients.

[0088] In some embodiments, the value of EF can be preset by the manufacturer based on a particular application (flow rate range). For example, for a given application, such as infusion pump flow measurement, factory testing is performed to determine the EF, which can be a preset value. One such value can be 50 for flow rates of 1 to 1000 ml / hr, for end of flow head lengths ranging from 50 mm to 300 mm.

[0089] Following step / action 623, method 600 proceeds to step / action 625. In the instance where the processing circuit determines at step / action 625 that the maximum allowable residence time value is less than the flow termination factor, the processing circuit generates a second bubble residence indication.

[0090] Following step / action 625, method 600 proceeds to step / action 627. At step / action 627, in some embodiments, the processing circuitry determines whether (i) at least one flow sensing component output is below a predetermined minimum value (e.g., "T low "), and (ii) whether the flow sensing component / thermopile output voltage variation (e.g., dT) is equal to 0.01 mV. In instances where the processing circuit determines that the flow sensing component output does not meet or meet the predetermined minimum value and the voltage variation does not meet the threshold or range (e.g., not equal to 0.01 mV), method 600 returns to step / operation 601 and the processing circuit continues to monitor one or more sensing component outputs (e.g., thermopile outputs). However, in instances where the processing circuit determines that the flow sensing component output does meet or meet the predetermined minimum value and the voltage variation (dT) is equal to 0.01 mV, method 600 returns to step / operation 619.

[0091] Using the techniques disclosed herein, undesirable air / gas bubble conditions that can generate flow measurement errors can be detected. For example, air / gas bubbles can exist in a flow path where a flow sensing component (thermal flow sensing chip) is configured to invasively and directly contact the flow medium (e.g., liquid, fluid, etc.). According to some embodiments of the present disclosure, invasive / direct placement of the flow sensing component (e.g., sensing chip) within the flow path can reduce the thermal sensor heater drive current while maintaining improved flow sensitivity. As described herein, microturbulence effects from sensing chip edge interactions with the upstream flow on the exemplary sensing chip, along with sensing chip hydrophobic forces on the sensing chip, can result in a thin air film that acts as a dynamic flow boundary layer between the sensing chip and the flow to reduce flow friction compared to a thermal isolation layer. Certain embodiments of the present disclosure provide for detecting air / gas bubbles in a flow medium that arise from the flow medium while it is passing adjacent to or over a flow sensing component (e.g., a sensing tip) based at least in part on a sudden change in the temperature sensor output compared to a previously measured value and each temperature sensor output being at or below a predetermined value equal to a bubble presence temperature value. Additionally, as described herein, aspects of the present disclosure facilitate distinguishing between passing air bubbles and air bubbles trapped in an air film adjacent to or over the flow sensing component / sensing tip. In some embodiments, aspects of the present disclosure provide techniques for detecting an end-of-flow condition and generating an indication / alert associated therewith.

[0092] While various embodiments according to the principles disclosed herein have been shown and described above, modifications thereto may be made by those skilled in the art without departing from the teachings of the present disclosure. The embodiments described herein are merely representative and are not intended to be limiting. Many variations, combinations, and modifications are possible and fall within the scope of the present disclosure. Alternative embodiments resulting from combining, integrating, and / or omitting features of the embodiments are also within the scope of the present disclosure. Accordingly, the scope of protection is not limited by the above description, but is defined by the claims that follow, including all equivalents of the subject matter of the claims. Each and every claim is incorporated herein as further disclosure, and the claims are embodiments of the present disclosure. Furthermore, while any advantages and features described above may relate to particular embodiments, application of such issued claims is not limited to processes and structures achieving any or all of the above advantages or having any or all of the above features.

[0093] Additionally, the section headings used herein are provided to conform to the proposal under Title 37, Code of Federal Regulations, Section 1.77, or to otherwise provide organizational guidance. These headings do not limit or characterize the disclosure set forth in any claims that may issue from this disclosure. For example, the description of a technology in the "Background" section should not be construed as an admission that a particular technology is prior art to any disclosure in this disclosure. The "Abstract" section also should not be considered a limiting feature of the disclosure that will be set forth in the claims to be issued. Furthermore, any reference in this disclosure to the singular "disclosure" or "embodiments" should not be used to assert that there is only a single point of novelty in the disclosure. Multiple embodiments of the present disclosure may be set forth according to the limitations of the multiple claims that issue from this disclosure, and such claims therefore define the present disclosure and their equivalents protected thereby. In all cases, the claims should be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.

[0094] Additionally, the systems, subsystems, devices, techniques, and methods described and illustrated in various embodiments, individually or separately, may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other devices or components shown or described as coupled or in communication with each other may be indirectly coupled through some intermediate device or component, whether electrical, mechanical, or otherwise. Other examples of changes, substitutions, and alterations will be ascertainable by those skilled in the art and could be made without departing from the scope disclosed herein.

[0095] Many modifications and other embodiments of the disclosure described herein will come to mind to one skilled in the art to which these embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. While the drawings illustrate only certain components of the devices and systems described herein, various other components may be used in conjunction with the components and structures disclosed herein. It is to be understood, therefore, that the disclosure is not limited to the particular embodiments disclosed, and that 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 in another system, or certain features may be omitted, or not implemented. Furthermore, the steps in any method described above need not necessarily occur in the order depicted in the accompanying drawings; in some cases, one or more of the depicted steps may occur substantially simultaneously, or additional steps may be included. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. A flow sensing device comprising: Housing and a flow sensing component disposed at least partially within the housing, the flow sensing component configured to be in direct contact with a flow medium in a flow path of the flow sensing device; a controller component in electronic communication with the flow sensing component, monitoring at least one flow sensing component output; detecting an air bubble adjacent a surface of the flow sensing component based at least in part on the at least one flow sensing component output; determining whether the bubble satisfies a bubble condition defining one or more predetermined characteristics; generating a bubble indication in response to determining that the bubble satisfies the bubble condition. the flow sensing device is positioned such that when the flow medium directly contacts the flow sensing device, a void is formed adjacent a surface of the flow sensing device, and at least one of the predetermined characteristics is associated with the gas bubble adjacent the void; The controller component comprises: initiating a bubble dwell timer in response to detecting the bubble; determining a minimum acceptable residence time value; determining a maximum allowable residence time value; generating an air bubble residence time indication in the event that the maximum allowable residence time value is less than an air bubble residence time value.

2. The controller component comprises: determining a first temperature output associated with the first flow sensing element; determining a second temperature output associated with the second flow sensing element; 2. The flow sensing device of claim 1, configured to determine whether the bubble satisfies the bubble condition by: comparing the first temperature output with the second temperature output.

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