Integrated sensor for monitoring fluid transport

Abstract

A sensor for fluid flow applications is provided. The sensor includes: an inlet chamber configured to receive fluid flow from a first conduit; an outlet chamber configured to supply fluid flow to a second conduit; and a diaphragm separating the inlet and outlet chambers, the diaphragm including a fluid channel to allow fluid flow from the inlet chamber to the outlet chamber. The sensor also includes: circuitry disposed on the diaphragm, the circuitry having electrical properties configured to change according to deformation of the diaphragm; and a conductor formed on a substrate and coupled to the circuitry, providing an electrical signal based on changes in the electrical properties of the circuitry. The diaphragm includes an epitaxial layer formed on the substrate. Methods for manufacturing and using the above-described sensor are also proposed.

Description

[0001] This application is a divisional application of Chinese patent application No. 201980013186.5, filed on February 12, 2019, entitled "Integrated Sensor for Monitoring Fluid Transport". Technical Field

[0002] This disclosure generally relates to apparatuses and methods for measuring and controlling fluid flow. More specifically, this disclosure relates to apparatuses and methods for using microelectromechanical moving systems (MEMS) to measure fluid flow parameters in fluid transport applications. Background Technology

[0003] Many methods for fluid delivery involve the measurement of multiple fluid flow parameters related to fluid flow control. Some of these parameters are particularly relevant in medical applications (e.g., intravascular drug delivery, subcutaneous drug delivery, etc.). In addition to measuring multiple parameters, it is desirable to provide a compact form factor that is easy to handle and facilitates movement and access to the device (e.g., healthcare providers, patients, etc. in medical applications). Typically, devices for measuring multiple fluid parameters are not compact and include moving parts that hinder their use in applications requiring easy access (e.g., emergency rooms in medical facilities). Summary of the Invention

[0004] In a first embodiment, a sensor for fluid flow applications is proposed. The sensor includes: an inlet chamber configured to receive fluid flow from a first conduit; an outlet chamber configured to supply fluid flow to a second conduit; and a diaphragm separating the inlet and outlet chambers, the diaphragm including fluid channels to allow fluid flow from the inlet chamber to the outlet chamber. The sensor also includes: circuitry disposed on the diaphragm, the circuitry having electrical properties configured to change according to deformation of the diaphragm; and a conductor formed on a substrate and coupled to the circuitry, providing an electrical signal based on changes in the electrical properties of the circuitry. The diaphragm includes an epitaxial layer formed on the substrate.

[0005] In some embodiments, a method for manufacturing a sensor is proposed. The method includes: growing an epitaxial layer on a substrate, wherein forming the epitaxial layer includes selectively implanting dopant atoms to form strain-sensitive electrical components in the epitaxial layer; and forming a diaphragm on the epitaxial layer, the diaphragm having a selected thickness such that a pressure difference between opposite sides of the diaphragm induces strain in the epitaxial layer. The method further includes: forming a fluid channel through the diaphragm; attaching an inlet fitting to the substrate to form an inlet chamber on a first side of the diaphragm; attaching an outlet fitting to the substrate to form an outlet chamber on a second side of the diaphragm; and attaching an electrical connector to the electrical components.

[0006] In another embodiment, a method for controlling fluid flow is proposed. The method includes: providing fluid flow through a sensor including a diaphragm separating an inlet chamber from an outlet chamber, the diaphragm including fluid channels, wherein the diaphragm includes an epitaxial layer formed on a substrate; and providing power to a piezoresistive element on the diaphragm, wherein the piezoresistive element is configured to measure deformation of the diaphragm separating the inlet and outlet chambers. The method further includes: detecting deformation of the diaphragm based on changes in the electrical properties of the piezoresistive element on the diaphragm; obtaining the flow velocity of the fluid flow through the sensor based on the deformation of the diaphragm; and using a controller to modify fluid flow parameters based on the flow velocity. Attached Figure Description

[0007] Figure 1 A fluid flow system including a sensor for monitoring fluid flow is shown according to some embodiments.

[0008] Figure 2 A sensor for monitoring fluid flow is shown according to some embodiments.

[0009] Figure 3A -G illustrates a method for manufacturing according to some embodiments. Figure 2 The steps of a method for monitoring fluid flow using sensors.

[0010] Figure 4 A flowchart is shown of a method for manufacturing a sensor to monitor fluid flow according to some embodiments.

[0011] Figure 5 A flowchart is shown for a method for monitoring fluid flow using sensors, according to some embodiments.

[0012] In the accompanying drawings, unless otherwise expressly stated, elements with the same or similar reference numerals have the same or similar functions or configurations. Detailed Implementation

[0013] This disclosure discloses a monolithically integrated sensor for monitoring five parameters during IV fluid transport. Some embodiments include sensing modes such as fluid flow rate, fluid pressure (gauge pressure relative to ambient atmosphere), fluid conductivity, temperature, and the presence of bubbles. Embodiments consistent with this disclosure include integrating one or more of the above sensing modes into a single device, and a method of manufacturing the device.

[0014] Some advantages of embodiments consistent with this disclosure include the ability to combine different sensing modes into a small, monolithic package. Furthermore, the embodiments disclosed in this application provide a low-cost, high-volume manufacturing method for production equipment.

[0015] The embodiments disclosed in this application may include the application of fluid sensors in intravascular drug delivery. More generally, embodiments consistent with this disclosure may include the application of fluid systems in subcutaneous fluid delivery for medical applications, or in implantable systems that can directly deliver fluid to organs, tumors, etc., for compounding, removing bodily fluids, and other therapeutic applications.

[0016] Figure 1 A fluid flow system 10, including a sensor 100 for monitoring fluid flow, is shown according to some embodiments. The fluid flow system 10 may include a frame 140 supporting a container 143 having fluid 150. In some embodiments, the fluid flow system 10 may include a fluid extraction system to extract sample fluid from a patient 160. Furthermore, in some embodiments, the fluid flow system 10 may transfer fluid 150 from a first vessel or container to a second vessel or container, for example, for drug preparation and / or storage purposes.

[0017] In some embodiments, the fluid flow system 10 is an intravenous delivery system, and the fluid 150 may include intravenous fluid to be administered to patient 160 via a blood vessel. Therefore, the fluid 150 may include blood, plasma, or a drug. In some embodiments, the fluid 150 includes a soluble gas, which may be in the form of bubbles 151, or may form a gas phase above the liquid surface, or include any combination of these forms. The gas in the bubbles 151 may be air, nitrogen, oxygen, or any other gas readily soluble in the fluid 150. The fluid 150 may be any fluid suitable for intravenous delivery. Common intravenous fluids include crystalloids (e.g., saline, lactated Ringer's solution, glucose, dextran), colloids (e.g., hydroxyethyl starch, gelatin), liquid drugs, buffers, and blood products (e.g., congested red blood cells, plasma, clotting factors) or blood substitutes (e.g., artificial blood) intended to be injected intravenously into patient 160. The fluid line 130 transports the fluid 150 from container 143 to patient 160. In some embodiments, fluid 150 moves through fluid line 130 by a pressure differential created by gravity. Therefore, in some embodiments, container 143 is positioned at a higher height relative to the patient on frame 140. In some embodiments, pump 145 generates a pressure differential to move liquid 150 through fluid line 130.

[0018] Some embodiments of the fluid flow system 10 include a thermostat 147 to regulate the temperature of the fluid 150 in the container 143. The fluid flow system includes a sensor 100 fluidly coupled to the fluid line 130. The sensor 100 is configured to provide multiple measurements of the fluid flow. In some embodiments, the sensor 100 is configured to measure fluid pressure, fluid velocity, bubble concentration, fluid temperature, and fluid conductivity. In some embodiments, the sensor 100 is configured to measure the pressure difference between the fluid in the fluid delivery system 10 and atmospheric pressure P.

[0019] In some embodiments, the operation of the fluid flow system 10 can be wirelessly controlled by, for example, a remote control 170 located at a nurse's station. Wireless communication can be performed via an antenna 175 on the controller side and an antenna 155 on the frame 140. The controller 170 includes a processor 171 and a memory 172. The memory 172 may include commands and instructions that, when executed by the processor 171, cause the controller 170 to at least partially perform some of the steps included in the method according to this disclosure. Furthermore, the sensor 100 can wirelessly communicate with the antenna 155 and the controller 170 to receive commands from the controller 170 and provide data to the controller 170.

[0020] The controller 170, antenna 155, and sensor 100 can communicate via Bluetooth, Wi-Fi, or any other radio frequency protocol. Therefore, the controller 170 can be configured to process readings from the sensor 100 and determine fluid flow rate and other fluid characteristics related to drug transfer or injection. When the sensor 100 detects that the bubble content is below a predetermined threshold, a valve 190 in the fluid line 130 can be actuated to allow fluid 150 to flow into the patient 160. In some embodiments, the valve 190 can be closed by the controller 170 when an alarm is issued as described above.

[0021] Furthermore, when the bubble count in sensor 100 exceeds a threshold, controller 170 can provide an alarm to the centralized system. In some embodiments, controller 170 can also provide a command to thermostat 147 to adjust the temperature of fluid 150 based on the bubble count or temperature measurement provided by sensor 100.

[0022] Figure 2 A sensor 100 for monitoring fluid flow is illustrated according to some embodiments. In some embodiments, the sensor 100 may use silicon MEMS fabrication techniques to integrate multiple sensing capabilities into a package with a substantially reduced form factor. For example, but not limited to, as shown, some embodiments may include up to five or more sensing modes.

[0023] Sensor 100 includes an inlet chamber 251 configured to receive fluid flow 250 from a first conduit 253. An outlet chamber 252 is configured to supply fluid flow 250 to a second conduit 255. A diaphragm 202a separates the inlet chamber 251 from the outlet chamber 252. Diaphragm 201a may include a fluid channel 221 to allow fluid flow 250 from the inlet chamber 251 to the outlet chamber 252. In some embodiments, diaphragm 202a may be an epitaxial layer grown on a substrate 201, wherein the substrate 201 is subsequently etched into the “back side” (bottom of the figure) of diaphragm 202a. Thus, in some embodiments, the fluid channel 221 may be formed by etching orifices into diaphragm 202a.

[0024] In some embodiments, sensor 100 includes circuitry 210a disposed on diaphragm 202a. Circuitry 210a may be configured to change electrical properties according to deformation of diaphragm 202a. Some embodiments also include a plurality of conductors 217 formed on substrate 201 to provide power and receive electrical signals from different circuitry components in sensor 100. In some embodiments, conductors 217 provide electrical signals to circuitry 210a based on changes in the electrical properties of circuitry 210a to a circuit configured to use the electrical signals to obtain the flow rate of fluid flow 250. In some embodiments, diaphragm 202a is an epitaxial layer formed on substrate. In some embodiments, the sensing mode in sensor 100 may include a flow rate measurement based on Torricelli's law, which correlates the pressure drop between inlet chamber 251 and outlet chamber 252 across fluid channel 221 with the flow rate.

[0025] In some embodiments, circuit component 210a is a piezoresistive element, and its electrical property is resistance. Circuit component 210a is formed in and around the fluid channel 221 to detect deformation of the diaphragm 202a, which is related to the pressure difference between the inlet chamber 251 and the outlet chamber 252. Therefore, monitoring circuit component 210a can provide a direct measurement of the pressure drop across the diaphragm 202a, which can be used to calculate the flow velocity through the fluid channel 221 (e.g., using Torricelli's law).

[0026] Piezoresistive pressure sensors operate based on the piezoresistive principle, which is the dependence of a material's conductivity on the strain present in the material. Therefore, the diaphragm 202a forms a selectively doped piezoelectric resistor region (e.g., circuit element 210a). A pressure difference across the diaphragm 202a causes it to flex (or "buck") under applied stress. For example, the pressure difference across the diaphragm 202a is caused by a pressure drop in the fluid flow through the fluid channel 221. Internal stress generated by strain or deformation of the diaphragm 202a compensates for the pressure difference. Strain in the diaphragm 202a produces a change in resistance of the piezoresistive element 210a. This change in resistance can be detected electronically, for example, via a Wheatstone bridge circuit structure, which can be reached through one or more conductors 217.

[0027] Some embodiments include a second circuit component 210b disposed on a second diaphragm 202b. The second diaphragm 202b separates the outlet chamber 252 from atmospheric pressure P. In a non-limiting manner, some embodiments may include the second diaphragm 202b separating the inlet chamber 251 from atmospheric pressure P. Thus, one side of the diaphragm 202b is in contact with the fluid 150, and the other side is exposed to atmospheric pressure P. Therefore, the diaphragm 202b deforms (e.g., "strains") to compensate for the pressure difference between the fluid 150 (in either the inlet chamber 251 or the outlet chamber 252) and atmospheric pressure P. For example, when atmospheric pressure P is greater than the fluid pressure in outlet chamber 252, the diaphragm 202b may "recess" into outlet chamber 252. Conversely, when atmospheric pressure P is lower than the fluid pressure in outlet chamber 252, the diaphragm 202b may "bulge" out of chamber 252. Diaphragms 202a and 202b will be collectively referred to as "diaphragm 202" below. In some embodiments, the second circuit component 210b may be configured to change its electrical properties according to the deformation of the second diaphragm 202b. For example, the second circuit component 210b may include a piezoresistive element configured to change its resistivity as it deforms with the deformation of the second diaphragm 202b. Hereinafter, circuit component 210a and the second circuit component 210b will be collectively referred to as "circuit component 210". Therefore, a principle similar to that used in the flow rate measurement described above is employed to monitor the fluid pressure relative to atmospheric pressure P in one of the inlet chamber 251 or outlet chamber 252.

[0028] In some embodiments, substrate 201 includes a semiconductor material (e.g., silicon, germanium, gallium arsenide, and any combination or alloy of the above materials), and diaphragm 202 includes an epitaxial layer grown over the semiconductor material.

[0029] Some embodiments also include electrodes 203a and 203b (hereinafter collectively referred to as "electrode 203") deposited on substrate 201. Electrode 203 may be configured to contact fluid 150 to measure electrical properties of fluid 150, such as fluid conductivity. Fluid conductivity is monitored by measuring the impedance between electrodes 203, which are arranged in a defined geometry (e.g., horizontally along a predetermined distance, such as...). Figure 2 (As shown) is exposed to fluid 150. Conductor 217 can supply current, such as direct current (DC), to electrode 203. Therefore, DC impedance and geometric factors produce fluid conductivity.

[0030] Some embodiments also include electrodes 205a and 205b (hereinafter collectively referred to as "electrodes 205") deposited on a substrate and separated from the fluid 150 by passivation layers 207a and 207b (hereinafter collectively referred to as "passivation layer 207"), respectively. Electrodes 205 can be configured to measure the capacitance of the fluid 150, which can indicate the dielectric properties of the fluid 150. In some embodiments, electrodes 205 are configured to measure the bubble content in the fluid by the value of the dielectric constant ε of the fluid 150. The capacitance between electrodes 205 can be determined by the dielectric properties of the fluid 150. For example, because water has a higher dielectric constant, the capacitance can be higher when water or some fluid with a high dielectric constant fills the gap between electrodes 205 compared to an air gap with the same geometry. In some embodiments, sensor 100 monitors the capacitance between electrodes 205 over time, thereby detecting the presence and size of bubbles.

[0031] In some embodiments, sensor 100 includes a temperature sensor 215 to measure the fluid temperature. In embodiments including silicon integrated circuits (e.g., MEMS), temperature sensor 215 may include a bandgap sensor, wherein the measured value varies based on a change in the voltage of a forward-biased diode, depending on the temperature of the PN junction. A voltage across temperature sensor 215 may be provided via conductor 217. In some embodiments, a thin passivation layer is formed over the PN junction to electrically isolate the diode from the fluid while still allowing thermal equilibrium between the fluid and the PN junction. Temperature compensation and linearization circuitry may also be included on-chip.

[0032] Alternative arrangements of the components may be equally effective; the specific arrangement shown in the figures is merely one possible solution. On the one hand, for compact, easy-to-use applications, there is a strong need for monolithic integration of five sensing functions within a single silicon MEMS chip.

[0033] Sensor 100 can be integrated into various systems and components, or connected as a standalone module to the patient's IV access port. For example, it can be integrated into a micropump device to provide active feedback on controlled flow and to issue an alarm when pressure or fluid conductivity is out of range or air is detected in the line. Alternatively, this low-cost sensor can be integrated into smart catheters, for example, to allow monitoring of all intravenous fluid delivery to the patient.

[0034] Figure 3A -G illustrates steps in a method for manufacturing an integrated sensor 100 to monitor fluid transport, according to some embodiments. Figure 3A -G illustrates a schematic diagram of a method for fabricating sensor 100 using standard silicon MEMS processes, showing cross-sections of the device at some fabrication steps. The device is embedded in a single silicon die and then integrated into a housing to provide fluid and electrical connectivity. For purely illustrative purposes and without loss of generality, Figure 3A The top of the substrate in -G will be referred to as the "front end", and Figure 3A In -G, the bottom end of the base will be referred to as the "back end".

[0035] Figure 3A Step 300A according to some embodiments is illustrated. In step 300A, a bare silicon wafer 301 has an epitaxial layer 311 grown on its front surface. Dopant atoms are selectively implanted into this epitaxial layer to form a piezoelectric resistor element 210. When the substrate material comprises a semiconductor such as silicon, the dopant atoms may include electron donor atoms such as phosphorus (P) or arsenic (As), or electron acceptor atoms such as boron (B) or aluminum (Al), or any combination of donor and acceptor atoms. The deflection of the silicon diaphragm due to the transdiaphragm pressure difference can be detected by the resistance change of these implanted regions caused by strain in the lattice.

[0036] Figure 3B Step 300B according to some embodiments is shown. In step 300B, a temperature sensor circuit 215 is disposed on the front side of the silicon wafer 301.

[0037] Figure 3C Step 300C according to some embodiments is shown. In step 300C, separators 202a and 202b are formed by deep silicon etching from the back side of silicon wafer 301.

[0038] Figure 3DStep 300D according to some embodiments is shown, wherein the fluid channel 221 is etched through the diaphragm 202a adjacent to the piezoelectric resistor component 210a. In step 300D, the fluid channel 221 allows the fluid flow 250 to proceed from the front end to the rear end of the silicon wafer 301. Once the fluid channel 221 is formed in the diaphragm 221, the substrate 301 is formed in the shape of the substrate 201, as described in detail above.

[0039] Figure 3E Step 300E according to some embodiments is shown. In step 300E, backside metallization is performed to form electrode 203 for a conductivity sensor and electrode 205 for a capacitive sensor. In some embodiments, this can be done in one step (if electrodes 203 and 205 are stacked from the same material) or in multiple steps. Electrodes 203 and 205 do not need to be the same material because electrode 203 is exposed to fluid 150, while electrode 205 is not. Electrode 205 is deposited on the sidewall of diaphragm 202a. This can be done by a stripping process, or alternatively, metal can be uniformly deposited and then etched from the surface area.

[0040] Figure 3F Step 300F according to some embodiments is illustrated. In step 300F, a passivation layer 307 is deposited on the back side of substrate 201 to isolate electrode 205 from fluid 150, and selective etching is performed to open windows, thereby exposing electrode 203 to fluid 150. In some embodiments, in step 300F, front-side isolation and metallization are performed to establish selective contact between pressure sensor, flow sensor, and temperature sensor 215 and piezoelectric resistor 210.

[0041] In some embodiments, step 300F includes passivating the front side of substrate 301 with an additional passivation layer 321 to isolate electrical components from fluid paths. The passivation material used for passivation layers 307 or 321 may include a conformal polymer such as parylene or an inorganic glass layer such as silicon dioxide.

[0042] Figure 3G Step 300G according to some embodiments is illustrated. In some embodiments, in step 300G, the fitting 221 is attached to the sensor mold via adhesive portion 350. In some embodiments, step 300G includes: wire bonding to the respective electrodes and final encapsulation in the housing to complete the MEMS process.

[0043] Figure 4A flowchart is shown of a method 400 for fabricating an integrated sensor (e.g., sensor 100) to monitor fluid transport, according to some embodiments. Thus, in some embodiments, method 400 includes forming a sensor on a semiconductor substrate (e.g., substrate 201) using a MEMS configuration. The integrated sensor in method 400 may include multiple components configured to measure fluid properties such as flow rate, pressure, salinity, bubble content, etc.

[0044] The steps in method 400 may be performed in overlapping or nearly simultaneously. Furthermore, some embodiments consistent with this disclosure may include at least, but not all, of the steps shown in method 400, performed in any order.

[0045] Step 402 includes growing an epitaxial layer over the front side of a semiconductor substrate. In some embodiments, step 402 includes selectively implanting dopant atoms to form strain-sensitive electrical components in the epitaxial layer. In some embodiments, step 402 includes forming a piezoresistive element for pressure and flow rate measurement together with the selectively implanted dopant atoms. The piezoresistive element may have a resistivity that changes according to strain induced in the epitaxial layer.

[0046] Step 404 includes: forming a temperature sensing circuit on the epitaxial layer.

[0047] Step 406 includes forming a separator in the semiconductor substrate. In some embodiments, step 406 may include etching the back side of the semiconductor substrate down to the epitaxial layer formed on the front side. Therefore, in some embodiments, step 404 includes selecting the thickness of the separator such that a pressure difference between opposite sides of the separator (e.g., front and back ends) causes strain in the epitaxial layer.

[0048] Step 408 includes forming a fluid channel through a portion of a diaphragm region, the diaphragm region including at least one piezoresistive element. In some embodiments, step 408 includes etching said portion of the diaphragm to form the fluid channel.

[0049] Step 410 includes depositing a back metallization layer onto a selected region of a semiconductor substrate, the selected region including a conductivity sensor and a bubble sensor.

[0050] Step 412 includes depositing a passivation layer on the back side of a semiconductor substrate to isolate a pair of capacitive electrodes from the fluid.

[0051] Step 414 includes etching a passivation layer in a selected area to expose the electrodes for the conductivity sensor to the fluid.

[0052] Step 416 includes depositing a metallization layer and a passivation layer on the front side of a semiconductor substrate to form selective circuit contacts for a piezoresistive element in a pressure and flow sensor.

[0053] Step 418 includes depositing a passivation layer on the front side of a semiconductor substrate to isolate electrical components from fluids.

[0054] Step 420 includes connecting inlet and outlet fittings to the sensor mold to form an inlet chamber and an outlet chamber (e.g., inlet chamber 251 and outlet chamber 252) separated by a diaphragm.

[0055] Step 422 includes applying wire bonding to the individual electrodes for final packaging.

[0056] Figure 5 A flowchart of a method 500 for monitoring fluid flow using an integrated sensor, according to some embodiments, is shown. Methods consistent with method 500 may include using an integrated sensor (e.g., integrated sensor 100) having at least one measuring component, as disclosed in this application. Further, according to some embodiments, methods consistent with this disclosure may include an IV delivery system (e.g., fluid flow system 10) as disclosed in this application. An IV delivery system may include: a frame, fluid container, pump, thermostat, fluid line, antenna, sensor, and valve (e.g., frame 140, fluid container 143, pump 145, fluid line 130, antenna 155, sensor 100, and valve 190, see [link to relevant documentation]). Figure 1 ).

[0057] A method consistent with method 500 may include: a controller comprising a memory and a processor (e.g., controller 170, processor 171, and memory 172, see...). Figure 1 At least one step of method 500 is executed. Commands are stored in the memory that, when executed by the processor, cause the controller to execute at least one step of method 500. Further, according to some embodiments, a method consistent with method 500 may include: Figure 5 The method disclosed herein includes at least one step, but not all steps. Furthermore, in some embodiments, the method may include steps that are compatible with… Figure 5 The steps in method 500 are executed in different orders as shown. For example, in some embodiments, at least two or more steps in method 500 may overlap in time, or even be executed simultaneously or quasi-simultaneously.

[0058] Step 502 includes providing fluid flow through a sensor, the sensor including a diaphragm (e.g., membrane 202a, inlet chamber 251, outlet chamber 252) separating an inlet chamber and an outlet chamber.

[0059] Step 504 includes: providing electrical energy to a piezoresistive element in the sensor, the piezoresistive element being configured to measure the deformation of the diaphragm separating the inlet chamber and the outlet chamber.

[0060] Step 506 includes: detecting diaphragm deformation based on changes in the electrical properties of the piezoresistive component in the sensor.

[0061] Step 508 includes: obtaining the flow rate of the fluid flow through the sensor based on the deformation of the diaphragm.

[0062] Step 510 includes obtaining one of the conductivity, temperature, or bubble content of the fluid in the fluid flow. Step 510 may include performing a DC measurement of the impedance between two electrodes (e.g., electrode 203) having a known geometry relative to the fluid volume. To measure the impedance, step 510 may include applying a fixed voltage between the electrodes and measuring the resulting current. In some embodiments, step 510 may include applying a fixed current through the electrodes and measuring the resulting voltage. Step 510 may include selecting one of the above-described conductivity measurement methods based on the actual conductivity of the fluid. In some embodiments, step 510 may include implementing both of the above techniques to measure the conductivity of the fluid in the fluid flow. Based on the measured impedance and a geometric correction factor, the conductivity of the fluid in the fluid flow can be derived. Step 510 may include measuring the temperature of the fluid in the fluid flow using a temperature sensor, the temperature sensor including a diode with a PN junction (e.g., temperature sensor 215). Therefore, step 510 may include applying a fixed current through the diode and measuring the voltage across the junction. The forward voltage on a diode (used for constant current density) is linearly related to temperature over a wide operating range.

[0063] In some embodiments, step 510 may further include measuring the capacitance between a pair of electrodes (e.g., electrode 205). Therefore, step 510 may include monitoring the capacitance between the pair of electrodes over time; and detecting the presence and size of a bubble based on the capacitance value over time.

[0064] Step 512 includes providing the controller with at least one of the following: fluid flow rate, conductivity, temperature, or bubble content.

[0065] Step 514 includes: using a controller to modify fluid flow parameters based on at least one of flow rate, conductivity, temperature, or bubble content.

[0066] The foregoing description is provided to enable those skilled in the art to practice the various configurations described in this application. Although the subject matter has been specifically described with reference to various accompanying drawings and configurations, it should be understood that these are for illustrative purposes only and should not be considered as limiting the scope of the subject matter.

[0067] Many other ways may exist to implement the subject matter technology. Without departing from the scope of this subject matter technology, the various functions and elements described herein may be distinguished differently from those shown. Various modifications to these configurations will be apparent to those skilled in the art, and the general principles defined herein can be applied to other configurations. Therefore, those skilled in the art can make many changes and modifications to the subject matter technology without departing from its scope.

[0068] As used in this application, the phrase "at least one" preceding a series of items, separated by the terms "and" or "or," modifies the list as a whole rather than a list of each member of the list (e.g., each item). The phrase "at least one" does not require selection of at least one of each listed item; rather, the phrase allows for the inclusion of at least one of any one of the items and / or at least one of any combination of the items and / or at least one of each item. For example, the phrases "at least one of A, B, and C" or "at least one of A, B, or C" respectively refer to only A, only B, or only C; any combination of A, B, and C; and / or at least one of each of A, B, and C.

[0069] Furthermore, the use of terms such as "comprising," "having," etc., in the specification or claims is intended to encompass in a manner similar to the term "comprising," as it is interpreted as "comprising" when used as a transitional word in the claims. The word "exemplary" is used in this application to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" in this application is not necessarily to be construed as preferred or advantageous over other embodiments.

[0070] Unless otherwise specified, reference to elements in the singular is not intended to mean "one and only one," but rather "one or more." The term "some" refers to one or more. All structures and functions of elements equivalent to the various constructions described throughout this disclosure, which are known or will be known hereafter by one of ordinary skill in the art, are expressly incorporated herein by reference and are intended to be covered by the subject matter. Furthermore, whether or not such disclosure is expressly stated in the foregoing description, nothing disclosed in this application is intended for public use only.

[0071] Although certain aspects and implementations of the subject matter have been described, these are given by way of example only and are not intended to limit the scope of the subject matter. In fact, the novel methods and systems described herein may be embodied in various other forms without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of the subject matter.

Claims

1. A method for manufacturing a sensor assembly for use in fluid flow applications, the method comprising: An epitaxial layer is grown on a first side of a substrate, wherein forming the epitaxial layer includes selectively implanting dopant atoms to form strain-sensitive electrical components in the epitaxial layer; A diaphragm is formed on the epitaxial layer by deep silicon etching from a second side of the substrate. The thickness of the diaphragm causes strain in the epitaxial layer due to the pressure difference between opposite sides of the diaphragm. Forming fluid channels through the diaphragm; The inlet fitting is attached to the first side of the base to form an inlet chamber on the first side of the diaphragm; The outlet fitting is attached to the second side of the substrate to form an outlet chamber on the second side of the diaphragm; and Connect the electrical connector to the electrical component; A temperature sensing element is formed on a first side of the substrate; A metallization layer is deposited onto a selected area of ​​the substrate to form a capacitive sensor; The metallization layer is formed as one or more electrodes on the sidewall of the substrate in the outlet chamber, the sidewall being disposed between a first side and a second side of the substrate.

2. The method according to claim 1, wherein, The electrical components are formed as one or more piezoresistive elements.

3. The method according to claim 1, wherein, The electrical components are located on the first side of the diaphragm inside the entrance chamber.

4. The method according to claim 1, wherein, The temperature sensing element is formed in the epitaxial layer.

5. The method of claim 1, further comprising forming a second electrical connector on a first side of the substrate, the second electrical connector being connected to the temperature sensing component.

6. The method according to claim 1, wherein, The diaphragm is formed by deep silicon etching from the second side of the substrate.

7. The method of claim 1, further comprising depositing a metallization layer onto a selected region of the substrate to form a conductivity sensor.

8. The method according to claim 7, wherein, The metallization layer is formed as one or more electrodes on the second side of the substrate in the outlet chamber.

9. The method of claim 1, further comprising depositing a passivation layer over the metallization layer, the passivation layer separating the metallization layer from the fluid in the outlet chamber.

10. The method of claim 1, further comprising depositing a metallization layer and a passivation layer over the diaphragm to form an electrical contact with the electrical component.

11. The method of claim 1, further comprising depositing a passivation layer on the substrate and etching the passivation layer in the substrate.

12. The method of claim 1, further comprising forming a second diaphragm on a first side of the substrate outside the inlet chamber, the second diaphragm separating atmospheric pressure from the outlet chamber.

13. The method of claim 12, further comprising forming a second electrical component on the second diaphragm to measure fluid pressure from strain in the second diaphragm.

14. The method of claim 13, further comprising forming a second electrical connector on a first side of the substrate, the second electrical connector being connected to the second electrical component.

15. The method of claim 1, further comprising forming a passivation layer on a first side of the substrate to isolate the electrical components from the fluid in the inlet chamber.

16. The method according to claim 1, wherein, The inlet fitting and the outlet fitting are attached to the first and second sides of the substrate via adhesive portions.

17. The method of claim 1, further comprising encapsulating the sensor assembly in a housing.

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