Microwave flow sensing chip applied to fuel cell control

Abstract

The application discloses a microwave flow sensing chip applied to fuel cell control, comprising a microfluidic chip and a capacitance array sensing chip; the microfluidic chip comprises a microfluidic gas channel, a microfluidic liquid channel and a microfluidic mixing channel connected with each other, and the microfluidic mixing channel comprises a plurality of microfluidic mixing channel units; the capacitance array sensing chip comprises a substrate and a capacitance sensing structure arranged on the substrate, and the capacitance sensing structure comprises a plurality of bubble measuring units which are in one-to-one bonding with the plurality of microfluidic mixing channel units. The microwave flow sensing chip provided by the application is composed of a microfluidic chip and a capacitance array sensing chip, has the ability of fast and accurate measurement and control of gas flow, and can perform more reliable and efficient flow monitoring. The microwave flow sensing chip can significantly improve the stability and performance of a fuel cell system, thereby promoting the application development of the fuel cell system in the field of energy conversion.

Description

TECHNICAL FIELD

[0001] The present application relates to a microwave flow sensing chip applied to fuel cell control, belonging to the technical field of microwave flow sensors. BACKGROUND

[0002] In the context of increasing global energy demand and environmental pollution, renewable energy technologies are gradually becoming a hot research field. Among various renewable energy technologies, fuel cells show great application potential due to their high efficiency, cleanliness and sustainability. For fuel cells, control technology is particularly critical, as it directly relates to energy output efficiency, system safety and operation stability. Fuel cells convert chemical energy into electrical energy through electrochemical reactions, and in this process, microwave flow sensing chips play a crucial role. This chip can accurately measure and control the flow of reaction gases, thereby optimizing battery performance and ensuring efficient and stable energy conversion processes, which is of great significance for promoting the development and application of fuel cell technology.

[0003] Microwave flow sensing chips use advanced microwave technology to measure fluid flow. It accurately detects the speed and flow of fluids by transmitting and receiving microwave signals. This sensing chip uses a non-contact measurement method, making it very suitable for flow monitoring in high-temperature, high-pressure or corrosive environments. Thanks to its fast response time and high measurement accuracy, the microwave flow sensing chip can provide stable and reliable data without being affected by the physical and chemical properties of the fluid. In the field of fuel cell technology, the key role of the microwave flow sensing chip is to monitor and control the flow of hydrogen, air and other reaction gases in real time, which is crucial for ensuring efficient energy output and system stability of fuel cells. By accurately regulating gas flow, the microwave flow sensing chip helps optimize the performance of fuel cells, improve their energy conversion efficiency, and thus promote the widespread application of fuel cell technology in the field of clean energy.

[0004] Although traditional flow meters, such as differential pressure and mass flow meters, have made significant contributions in the field of gas flow measurement, they still have limitations in terms of measurement accuracy, stability, response speed, and susceptibility to changes in fluid density. Microfluidic channel technology effectively reduces environmental factors that interfere with measurements by precisely controlling gas flow. By placing a capacitive array sensor at key locations in the microfluidic channel, when gas flows, it changes the dielectric properties of the capacitive array within the channel, such as gas density and flow rate, resulting in changes in capacitance values. There is a certain functional relationship between this capacitance change and gas flow, allowing gas flow to be measured with high precision. Therefore, using microfluidic technology combined with capacitive array sensors as a microwave flow sensor to measure gas flow is becoming a rapidly developing emerging technology. The development of this technology not only improves the energy output efficiency of fuel cells, but also optimizes operating parameters, reduces fuel consumption, and improves the overall efficiency of the system. With continued technological advancements, microwave flow sensors have a promising future in the energy sector and are expected to play an increasingly important role in the future. SUMMARY

[0005] The present application aims to provide a microwave flow sensing chip for fuel cell control, which can solve the challenges faced by existing microwave flow sensors in application, including environmental interference, temperature compensation difficulties, and limitations of intelligent algorithms. The microwave flow sensing chip is specifically designed for fuel cell flow control, combining a microfluidic chip and a capacitive array sensing chip, with the ability to quickly and accurately measure and control gas flow, enabling more reliable and efficient flow monitoring. Through this design, the stability and performance of the fuel cell system can be significantly improved, thereby promoting its application and development in the field of energy conversion.

[0006] In a first aspect, the present application provides a microwave flow sensing chip, comprising a microfluidic chip and a capacitive array sensing chip.

[0007] The microfluidic chip comprises a microfluidic gas channel and a microfluidic liquid channel connected to each other, and a microfluidic mixing channel connected at the connection between the microfluidic gas channel and the microfluidic liquid channel, wherein the microfluidic mixing channel comprises a plurality of microfluidic mixing channel units; the microfluidic gas channel is used for introducing gas, the microfluidic liquid channel is used for introducing liquid, and one end of the microfluidic mixing channel is used for mixing the gas in the microfluidic gas channel and the liquid in the microfluidic liquid channel to form a bubble-containing liquid; the bubble-containing liquid is dispersed through a plurality of microfluidic mixing channel units from one end of the microfluidic mixing channel and converges at the other end of the microfluidic mixing channel.

[0008] The capacitive array sensing chip comprises a substrate and a capacitive sensing structure arranged on the substrate, and the capacitive sensing structure comprises a plurality of bubble measuring units, and the plurality of bubble measuring units are in one-to-one bonding with a plurality of microfluidic mixing channel units.

[0009] In an embodiment of the present application, the microfluidic gas channel and the microfluidic liquid channel are provided with electrically controlled valves at the connection with the microfluidic mixing channel.

[0010] In an embodiment of the present application, the microfluidic gas channel and the microfluidic liquid channel are connected with pluggable pipes at the end away from the microfluidic mixing channel, and the microfluidic mixing channel is provided with a liquid discharge port at the end away from the microfluidic gas channel and the microfluidic liquid channel.

[0011] In an embodiment of the present application, the microfluidic gas channel and the microfluidic liquid channel are both in straight line type structure, the number of the microfluidic mixing channel units is five, and the five microfluidic mixing channel units are arranged in parallel, and each of the microfluidic mixing channel units is connected with both ends of the microfluidic mixing channel.

[0012] In an embodiment of the present application, the bubble measuring unit comprises a capacitive sensing array measuring region, and the capacitive sensing array measuring region comprises a capacitor; the capacitor is an interdigital capacitor comprising two groups of electrodes, the two groups of electrodes are arranged in adjacent staggered arrangement and do not directly contact, and each group of electrodes is independently connected to a corresponding port provided with the capacitor.

[0013] In an embodiment of the present application, the shape of the two groups of electrodes is two combs placed in inclined staggered arrangement.

[0014] In an embodiment of the present application, the capacitor uses metal as electrode material and is coated on an insulating substrate by chemical deposition process; when the capacitor is connected to a power supply, charges are stored in the electric field between the two electrodes, and the electric field is mainly concentrated in the region between the electrodes, thereby generating a significant capacitive effect; the capacitance value depends on the area of the electrode, the distance between the adjacent electrodes, the dielectric constant of the dielectric material and the arrangement of the electrodes; by adjusting the above parameters, the size of the capacitor is accurately controlled, and the performance of the sensor is optimized;

[0015] The capacitance value C of the capacitor is calculated by the following formula:

[0016]

[0017] Wherein, is the relative dielectric constant of the dielectric material, is the vacuum dielectric constant, N is the total index of the interdigital electrode, i.e., the total number of electrodes, L is the length of each electrode, t is the thickness of the electrode, and d is the spacing between adjacent electrodes.

[0018] In a second aspect, the present application provides a flow sensor comprising the microwave flow sensing chip.

[0019] In a third aspect, the present application provides a liquid concentration detection method applied to fuel cell control, which uses the microwave flow sensing chip and comprises the following steps:

[0020] Step S101: input the liquid to be measured into the microfluidic liquid channel through the pluggable pipeline, and after flowing through the microfluidic mixing channel, enter the microfluidic mixing channel unit with one-to-five branch flow;

[0021] Step S102: measure the liquid to be measured in the five-way microfluidic mixing channel unit using the capacitive array sensing chip, obtain the capacitance value of the liquid to be measured, and take the average of the five capacitance values collected;

[0022] Step S103: change the concentration of the liquid to be measured and repeat the above operation to obtain the capacitance values of liquids with different concentrations;

[0023] Step S104: use COMSOL Multiphysics to simulate and obtain the change relationship curve between the concentration of the liquid to be measured and the capacitance value; as can be seen from the curve, the higher the concentration of the liquid to be measured, the greater the capacitance value.

[0024] In a fourth aspect, the present application provides a gas concentration detection method applied to fuel cell control, which uses the microwave flow sensing chip and comprises the following steps:

[0025] Step S201: input the gas to be measured into the microfluidic gas channel through the pluggable pipeline, input the liquid into the microfluidic liquid channel, control the flow of the gas and the liquid through the electrically controlled valve, form a liquid with bubbles after passing through the microfluidic mixing channel, and enter the microfluidic mixing channel unit with one-to-five branch flow;

[0026] Step S202: measure the bubbles in the liquid with bubbles in the five-way microfluidic mixing channel unit using the capacitive array sensing chip, and take the average of the capacitance values obtained by measuring the bubbles;

[0027] Step S203: change the flow of the gas input, and the liquid still flows at a constant speed, repeat the above operation, and obtain the capacitance values of the bubbles under multiple different gas flows;

[0028] Step S204, simulation is performed using COMSOL Multiphysics to obtain a curve of the relationship between the gas flow and the capacitance value; it can be seen from the curve that after the gas flow is changed, the size and flow rate of the bubbles change, thereby changing the dielectric constant in the channel, and finally leading to the change of the capacitance value; when the bubbles pass through the interdigital capacitance sensor, the capacitance value will change significantly; by monitoring the change of the capacitance value, the existence of the bubbles and the size and flow rate thereof are detected, so that the flow rate of the gas is determined.

[0029] The beneficial effects of the present application are:

[0030] The microwave flow sensing chip has high precision; by integrating the microfluidic chip and the capacitance array sensing chip, the microwave flow sensing chip can accurately measure the tiny gas flow, and the measurement precision significantly exceeds that of traditional technologies;

[0031] The microwave flow sensing chip can quickly respond; the capacitance array sensing chip used in the present application is optimized to realize efficient utilization of the capacitance electrodes and significantly improve the measurement precision. This improvement can realize real-time monitoring of the gas flow, and is especially suitable for tracking and analyzing dynamic gas flow;

[0032] The microwave flow sensing chip has simple structure and low cost; the application of microfluidic technology greatly simplifies the structure and reduces the cost, and is suitable for large-scale production and application.

[0033] The microwave flow sensing chip has wide applicability; the microwave flow sensing chip is suitable for various gas flow measurement scenes and can adapt to various industrial and laboratory environments, and has high application flexibility.

[0034] In summary, the microwave flow sensing chip applied to fuel cell control provided by the present application can solve the challenges faced by existing microwave flow sensors in application, including the interference of environmental factors, the problem of temperature compensation, and the limitations of intelligent algorithms. The microwave flow sensing chip is specially designed for the flow control of fuel cells, which is composed of a microfluidic chip and a capacitance array sensing chip, and has the ability to quickly and accurately measure and control the gas flow, and can perform more reliable and efficient flow monitoring. Through this design, the stability and performance of the fuel cell system can be significantly improved, thereby promoting the application development of the fuel cell system in the field of energy conversion. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The split schematic diagram of the microwave flow sensing chip provided by the present application.

[0036] Figure 2 The structure schematic diagram of the microfluidic chip provided by the present application.

[0037] Figure 3 Part structure schematic diagram of the capacitive array sensing chip provided by the application.

[0038] Figure 4 Capacitance simulation result diagram of the application.

[0039] Figure 5 Flow sensor simulation result diagram of the application.

[0040] In the figure: 1, microfluidic gas channel; 2, microfluidic liquid channel; 3, microfluidic mixing channel; 31, microfluidic mixing channel unit; 4, capacitive array sensing chip; 41, substrate; 42, bubble measurement unit; 421, capacitive sensing array measurement area; 5, pluggable pipe; 6, electrically controlled valve; 7, liquid discharge port. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0043] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or it can be detachable connection; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the connection between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] Please refer to Figure 1 , Figure 2 and Figure 3 The embodiment of the present application provides a microwave flow sensing chip, which comprises a microfluidic chip and a capacitive array sensing chip 4.

[0045] In some embodiments, the microfluidic chip comprises a microfluidic gas channel 1 and a microfluidic liquid channel 2 connected to each other, a microfluidic mixing channel 3 is connected to the connection of the microfluidic gas channel 1 and the microfluidic liquid channel 2, the microfluidic mixing channel 3 comprises a plurality of microfluidic mixing channel units 31; the microfluidic gas channel 1 is used to pass in gas, the microfluidic liquid channel 2 is used to pass in liquid, one end of the microfluidic mixing channel 3 is used to mix the gas in the microfluidic gas channel 1 and the liquid in the microfluidic liquid channel 2 to form a bubble-containing liquid, and the bubble-containing liquid is dispersed by a plurality of microfluidic mixing channel units 31 from one end of the microfluidic mixing channel 3 and then converges at the other end of the microfluidic mixing channel 3.

[0046] Optionally, the microfluidic gas channel 1 and the microfluidic liquid channel 2 are both linear structures, and a linear structure layout is adopted to facilitate the direct flow of gas or fluid.

[0047] Further, the number of microfluidic mixing channel units 31 is five, and the five microfluidic mixing channel units 31 are arranged side by side, and each microfluidic mixing channel unit 31 is connected to both ends of the microfluidic mixing channel 3.

[0048] In this embodiment, gas and liquid enter the microfluidic mixing channel 3 through the microfluidic gas channel 1 and the microfluidic liquid channel 2 respectively, and then are precisely mixed in the microfluidic mixing channel 3. The microfluidic mixing channel 3 adopts a branch type design and is divided into five branches, each branch flows through a microfluidic mixing channel unit 31, and each microfluidic mixing channel unit 31 is bonded to a capacitive sensor chip. This layout allows gas and liquid to be fully mixed in the microfluidic mixing channel 3 and then sequentially detected by the five capacitive sensor chips. After analysis by the capacitive array sensor chip 4, the mixed fluid is again converged and finally converges at the outlet of the microfluidic mixing channel 3. This structure design optimizes the flow characteristics of the fluid, ensures that the sensor chip can effectively mix and detect gas and liquid, and improves the measurement accuracy and efficiency of the microfluidic system.

[0049] Optionally, the microfluidic gas channel 1 and the microfluidic liquid channel 2 are provided with electrically controlled valves 6 at the connection with the microfluidic mixing channel 3.

[0050] In this embodiment, the electrically controlled valve 6 is used to accurately control the flow of gas and liquid. By adjusting the opening of the electrically controlled valve 6, the flow rate of the fluid can be controlled, thereby achieving accurate regulation of the flow of liquid and gas in the microfluidic system, ensuring the stability and repeatability of the system. At the same time, by adjusting the gas flow and keeping the liquid flowing at a constant speed, different mixing ratios of gas-liquid mixture can be achieved to form a liquid with bubbles.

[0051] In some embodiments, the microfluidic gas channel 1 and the microfluidic liquid channel 2 are connected to a pluggable pipe 5 at one end away from the microfluidic mixing channel 3.

[0052] In some embodiments, the microfluidic mixing channel 3 is provided with a liquid discharge port 7 at one end away from the microfluidic gas channel 1 and the microfluidic liquid channel 2. The outlet of the microfluidic mixing channel 3 is connected through the liquid discharge port 7.

[0053] In some embodiments, the capacitance array sensing chip 4 includes a substrate 41 and a capacitance sensing structure disposed on the substrate 41. The capacitance sensing structure includes a plurality of bubble measurement units 42, and each of the plurality of bubble measurement units 42 is bonded to one of the plurality of microfluidic mixing channel units 31.

[0054] In this embodiment, the substrate 41 is made of glass, and the capacitance array sensing chip 4 uses the glass substrate 41 as its structural basis and arranges a precise capacitance sensing structure on the substrate 41. The capacitance sensing structure is provided with bubble measurement units 42, and each of the plurality of bubble measurement units 41 is bonded to one of the plurality of microfluidic mixing channel units 31. The gas-liquid mixture flowing in the microfluidic mixing channel 3 forms a liquid flow containing bubbles. At this time, the capacitance array sensing chip 4 can accurately detect the generation of bubbles inside the microfluidic chip by real-time monitoring of the change of capacitance value. Since there is a significant difference in the dielectric constant between the bubble and the liquid medium, when the bubble passes through the capacitance sensing area, it will cause a significant fluctuation in the capacitance value. The capacitance array sensing chip 4 uses this principle to detect and identify bubbles in real time, ensuring the accuracy of the measurement process. Compared with directly measuring the capacitance value of the gas, the capacitance array sensing chip 4 exhibits higher precision in detecting the capacitance value of the bubble, providing an efficient and reliable technical means for monitoring bubbles in the microfluidic system.

[0055] Further, the bubble measurement unit 42 includes a capacitance sensing array measurement region 421, which includes a capacitor. The capacitor is an interdigital capacitor, including two groups of electrodes arranged adjacent to each other without direct contact, and each group of electrodes is independently connected to a corresponding port of the capacitor.

[0056] Alternatively, the shape of the two groups of electrodes is like two combs placed in an inclined staggered manner.

[0057] In this embodiment, the two sets of electrodes are arranged in an alternating pattern, resembling two combs placed at an angle. These two sets of electrodes are adjacent to each other but not in direct contact; each set of electrodes is independently connected to the corresponding port of the capacitor. The overlapping area between the electrodes, i.e., the sensitive area of ​​the capacitor, determines the capacitance value. By increasing the number of electrodes or extending their length, the capacitance value can be effectively increased, thereby improving the sensitivity of the sensor.

[0058] Compared to conventional interdigitated capacitors, the interdigitated capacitor provided by this invention features electrodes designed as two inclined, staggered combs arranged in an alternating pattern, while traditional interdigitated capacitors use vertically placed electrodes. This design allows for higher electrode area utilization in this invention, resulting in a larger electrode overlap area and a correspondingly larger capacitance value, thereby achieving higher measurement sensitivity.

[0059] Optionally, the capacitor array in this invention uses metallic copper as the electrode material, which is directly coated onto an insulating substrate using a chemical deposition process. Its working principle is based on the electric field formed between the two electrodes: when the capacitor is connected to a power source, charge is stored in the electric field between the two electrodes. Due to the very small distance between the electrodes and their close arrangement, the electric field is mainly concentrated in the region between the electrodes, thus producing a significant capacitance effect. The capacitance value depends on the area of ​​the electrodes, the distance between adjacent electrodes, the dielectric constant of the dielectric material, and the arrangement of the electrodes. By adjusting these parameters, the capacitance can be precisely controlled, thereby optimizing the sensor's performance.

[0060] The capacitance value R of the capacitor can be calculated using the following approximate formula:

[0061]

[0062] It is the relative permittivity of the dielectric material. is the vacuum permittivity, N is the total index of the interdigitated electrodes, i.e., the total number of electrodes, L is the length of each electrode, t is the thickness of the electrode, and d is the spacing between adjacent electrodes.

[0063] Specifically, in this embodiment, the capacitor linewidth is 100μm, the spacing is 95μm, the number of interdigitated fingers is 42, and the length is 1.9nm; the surface metal thickness of the two capacitors is 500nm, and the substrate thickness is 1mm; at a working frequency of 1MHz, the designed capacitance of the capacitive sensor is 17.29pF. Figure 4 As shown in the figure, the simulation results show that the capacitance value of the device remains unchanged at the operating frequency of 0-1GHz, proving that the capacitor has good stability.

[0064] Furthermore, the application also provides a flow sensor comprising the microwave flow sensor chip.

[0065] Furthermore, the application also provides a liquid concentration detection method applied to fuel cell control, which uses the microwave flow sensor chip and comprises the following steps.

[0066] In step S101, the liquid to be measured is input into the microfluidic liquid channel 2 through the pluggable pipeline 5, flows through the microfluidic mixing channel 3, and then enters the microfluidic mixing channel unit 31 with five branch flows.

[0067] In step S102, the capacitor array sensor chip 4 is used to measure the liquid to be measured in the five-way microfluidic mixing channel unit 31, and the average of the five measured capacitance values is obtained.

[0068] In step S103, the above operation is repeated with different concentrations of the liquid to be measured, and the capacitance values of the liquids with different concentrations are obtained.

[0069] In step S104, COMSOL Multiphysics is used for simulation, and the relationship curve between the concentration of the liquid to be measured and the capacitance value is obtained. As can be seen from the curve, the higher the concentration of the liquid to be measured, the greater the capacitance value.

[0070] The microfluidic chip is manufactured by using a standard PDMS (polydimethylsiloxane) manufacturing process, which is suitable for manufacturing microfluidic structures with high manufacturing precision. The capacitor array sensor chip 4 is used to measure the capacitance value of the liquid to be measured.

[0071] Furthermore, the application also provides a gas concentration detection method applied to fuel cell control, which uses the microwave flow sensor chip and comprises the following steps.

[0072] In step S201, the gas to be measured is input into the microfluidic gas channel 1 through the pluggable pipeline 5, the liquid is input into the microfluidic liquid channel 2, the flow of the gas and the liquid is controlled by the electrically controlled valve 6, the liquid with bubbles is formed after passing through the microfluidic mixing channel 3, and then enters the microfluidic mixing channel unit 31 with five branch flows.

[0073] In step S202, the capacitor array sensor chip 4 is used to measure the bubbles in the liquid with bubbles in the five-way microfluidic mixing channel unit 31, and the average of the capacitance values of the measured bubbles is obtained.

[0074] In step S203, the flow of the input gas is changed, the liquid still flows at a constant speed, and the above operation is repeated to obtain the capacitance values of the bubbles under multiple different gas flows.

[0075] Step S204: Use COMSOL Multiphysics to perform simulation and obtain the curve showing the relationship between gas flow rate and capacitance value. The curve shows that changing the gas flow rate changes the size and velocity of the bubbles, which in turn changes the dielectric constant in the channel, ultimately leading to a change in capacitance value. When the bubble passes through the interdigitated capacitive sensor, the capacitance value changes significantly. By monitoring the change in capacitance value, the presence of the bubble can be detected and its size and flow velocity can be measured, thereby determining the gas flow rate.

[0076] like Figure 5 As shown, a liquid with a dielectric constant of 80.36 was introduced into a microfluidic liquid channel 2 without any gas, and the measured capacitance was 94 pF. Subsequently, a small amount of gas was introduced into a microfluidic gas channel 1, causing the dielectric constant to drop to 79.36, and the corresponding capacitance to drop to 93 pF. As the gas flow rate gradually increased, the dielectric constant further decreased, and the capacitance also decreased accordingly. The bubbles generated above alter the dielectric constant within the microfluidic channel because the dielectric constant of bubbles is typically much lower than that of liquids (such as water). Therefore, when bubbles pass through an interdigitated capacitive sensor, the capacitance changes significantly. By monitoring the change in capacitance, the presence of bubbles can be detected, and their size and flow velocity can be measured, thereby determining the gas flow rate.

[0077] Specifically, the microfluidic channel has a diameter of 100 μm and a thickness of 50 μm, with a capacitor thickness of 500 nm. The substrate is a glass slide, and the microfluidic channel is formed by bonding the prepared PDMS electrode to the substrate. The capacitor electrode should be placed at the bottom of the microfluidic channel to ensure that the electric field can penetrate the fluid within the channel. Metal electrodes are deposited on the glass substrate using photolithography. Specific steps include substrate cleaning, photoresist coating, mask alignment and exposure, development, electrode metal deposition, and lift-off. The microfluidic channel is formed using a PDMS mold and then bonded to the electrode substrate to form a closed microfluidic system.

[0078] Furthermore, the present application provides a microwave flow sensing chip for fuel cell control. Taking a hydrogen fuel cell as an example, this technology directly converts the chemical energy of hydrogen (H2) and oxygen (O2) into electrical energy through an electrochemical reaction. Therefore, the flow control of hydrogen and oxygen is crucial for the performance of fuel cells. The present application mixes hydrogen and oxygen in precise proportions and then passes them into a microfluidic gas channel, while simultaneously passing a liquid into a microfluidic liquid channel. The flow of gas and liquid is precisely regulated using electrically controlled valves, and the mixed gas and liquid form a bubble-containing liquid in the mixing channel. This bubble-containing liquid is divided into five independent microfluidic mixing channel units through a one-to-five branch channel, and each microfluidic mixing channel unit is equipped with a capacitance array sensing chip. By measuring the capacitance value obtained by the gas bubbles and calculating the average value, the flow rate can be quantitatively determined. By changing the mixing ratio of hydrogen and oxygen and the flow rate of the mixed gas, the above measurement process is repeated. Finally, by using COMSOL Multiphysics simulation technology, the optimal hydrogen-oxygen mixing ratio and flow rate are determined to optimize the performance of the fuel cell.

[0079] Currently, one of the commonly used flow sensors in hydrogen fuel cell control is the Siargo MF5000 series gas mass flowmeter, which is favored for its high sensitivity, high precision, and strong anti-interference ability. However, its cost is relatively high, and its volume and weight are also relatively large, which limits its applicability in certain application scenarios. In contrast, the microwave flow sensing chip provided by the present application has the advantages of small size and low cost, and if applied to industrial production, it will significantly reduce costs and bring economic benefits.

[0080] In summary, the microwave flow sensing chip for fuel cell control provided by the present application has great application potential in the field of precise fluid control and analysis. This technology provides support for high-precision microfluidic operations by accurately monitoring gas flow, thereby promoting progress in the fields of biomedicine, chemistry, and environmental science. With the development of microfluidic technology, the integration and miniaturization level of capacitance sensors continue to improve, making them better suited to the needs of various microfluidic systems. If combined with artificial intelligence and big data analysis, the microfluidic capacitance detection system is expected to achieve automatic correction, environmental compensation, and intelligent analysis functions. These advances will further improve the accuracy of detection and expand its application range in different fields.

[0081] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A microwave flow sensing chip, characterized by, The microfluidic chip and the capacitive array sensing chip are included. The microfluidic chip includes a microfluidic gas channel and a microfluidic liquid channel connected to each other, and a microfluidic mixing channel is connected to the connection part of the microfluidic gas channel and the microfluidic liquid channel, the microfluidic mixing channel includes a plurality of microfluidic mixing channel units; the microfluidic gas channel is used for passing in gas, the microfluidic liquid channel is used for passing in liquid, one end of the microfluidic mixing channel is used for mixing the gas in the microfluidic gas channel and the liquid in the microfluidic liquid channel to form a bubble-containing liquid, and the bubble-containing liquid is dispersed through a plurality of microfluidic mixing channel units from one end of the microfluidic mixing channel and then converges at the other end of the microfluidic mixing channel. The capacitive array sensing chip includes a substrate and a capacitive sensing structure arranged on the substrate, and the capacitive sensing structure includes a plurality of bubble measuring units, and each of the plurality of bubble measuring units is bonded to one of the plurality of microfluidic mixing channel units.

2. The microwave flow sensing chip of claim 1, wherein, The connection part of the microfluidic gas channel and the microfluidic liquid channel and the microfluidic mixing channel is provided with an electrically controlled valve.

3. The microwave flow sensing chip of claim 1, wherein, The end of the microfluidic gas channel and the microfluidic liquid channel away from the microfluidic mixing channel is connected with a pluggable pipe; and the end of the microfluidic mixing channel away from the microfluidic gas channel and the microfluidic liquid channel is provided with a liquid discharge port.

4. The microwave flow sensing chip of claim 1, wherein, The microfluidic gas channel and the microfluidic liquid channel are both straight line structures, the number of the microfluidic mixing channel units is five, the five microfluidic mixing channel units are arranged side by side, and each of the microfluidic mixing channel units is connected to both ends of the microfluidic mixing channel.

5. The microwave flow sensing chip of claim 1, wherein, The bubble measuring unit includes a capacitive sensing array measurement region, the capacitive sensing array measurement region includes a capacitor; the capacitor is an interdigital capacitor including two groups of electrodes, the two groups of electrodes are arranged in adjacent staggered arrangement and do not directly contact each other, and each group of electrodes is independently connected to a corresponding port of the capacitor.

6. The microwave flow sensing chip of claim 5, wherein, The shape of the two groups of electrodes is like two combs placed in an inclined staggered manner.

7. The microwave flow sensing chip of claim 5, wherein, The capacitor uses metal as electrode material and is coated on an insulating substrate through a chemical deposition process; when the capacitor is connected to a power supply, charges are stored in the electric field between the two electrodes, and the electric field is mainly concentrated in the region between the electrodes, thereby generating a significant capacitive effect; The capacitance value of the capacitor depends on the area of the electrodes, the distance between the adjacent electrodes, the dielectric constant of the dielectric material, and the arrangement of the electrodes; by adjusting the above parameters, the size of the capacitor can be accurately controlled, and the performance of the sensor can be optimized; The capacitance value C of the capacitor is calculated by the following formula: wherein, is the relative permittivity of the dielectric material, is the vacuum permittivity, N is the total index of the interdigital electrodes, i.e. the total number of electrodes, L is the length of each electrode, t is the thickness of the electrodes, d is the spacing between adjacent electrodes.

8. A flow sensor, characterized by The microwave flow sensing chip of any one of claims 1-7 is included.

9. A liquid concentration detection method applied to fuel cell control, using the microwave flow sensing chip of any one of claims 1-7, comprising the following steps: In step S101, the liquid to be measured is input into the microfluidic liquid channel through the pluggable pipe, flows through the microfluidic mixing channel, and then enters the five-branch microfluidic mixing channel units; Step S102, the capacitor array sensing chip is used to measure the liquid to be measured in the five-way microfluidic mixing channel unit, the capacitance value of the liquid to be measured is obtained, and the five capacitance values collected are averaged; Step S103, the above operation is repeated by changing the concentration of the liquid to be measured, and the capacitance values of the liquids with different concentrations are obtained; Step S104, simulation is performed using COMSOL Multiphysics, and a curve of the relationship between the concentration of the liquid to be measured and the capacitance value is obtained; It can be seen from the curve that the higher the concentration of the liquid to be measured, the greater the capacitance value.

10. A gas concentration detection method applied to fuel cell control, using the microwave flow sensing chip of any one of claims 1-7, comprising the following steps: Step S201, the gas to be measured is input into the microfluidic gas channel through the pluggable pipeline, the liquid is input into the microfluidic liquid channel, the flow rates of the gas and the liquid are controlled by the electrically controlled valve, the liquid with bubbles is formed after passing through the microfluidic mixing channel, and enters the five-branch microfluidic mixing channel unit; Step S202, the capacitor array sensing chip is used to measure the bubbles in the liquid with bubbles in the five-way microfluidic mixing channel unit, and the capacitance values obtained by measuring the bubbles are averaged; Step S203, the flow rate of the input gas is changed, the liquid still flows at a constant speed, the above operation is repeated, and the capacitance values of the bubbles under multiple different gas flow rates are obtained; Step S204, simulation is performed using COMSOL Multiphysics, and a curve of the relationship between the gas flow rate and the capacitance value is obtained; It can be seen from the curve that after changing the gas flow rate, the size and flow rate of the bubbles change, thereby changing the dielectric constant in the channel, and finally causing the change of the capacitance value; when the bubbles pass through the interdigital capacitance sensor, the capacitance value will change significantly; by monitoring the change of the capacitance value, the existence of the bubbles is detected and the size and flow rate of the bubbles are measured, so as to determine the input flow rate of the gas.

Images