CN114100708B - Microfluid concentration sensing chip and microfluid characteristic measuring device - Google Patents

Abstract

The invention provides a microfluid concentration sensing chip and a microfluid characteristic measuring device, which relate to the technical field of microfluid measurement and control. Wherein, the microfluid concentration sensing chip includes a substrate, the substrate is provided with a micro heater and at least two sensing elements, the distance between each sensing element and the micro heater is different, and the sensing element is used to measure the heat of the fluid. Diffusion rate. The microfluidic characteristic measuring device comprises a measuring body and a microfluidic concentration sensor chip, the measuring body is provided with a fluid channel, the channel wall of the fluidic channel is provided with a measuring chamber, and the measuring chamber communicates with the fluidic channel; the microfluidic concentration sensor The chip is arranged on the channel wall, and the sensing surface of the microfluidic concentration sensing chip is located in the measurement chamber for measuring the thermal diffusivity of the fluid flowing into the measurement chamber, and the thermal diffusivity is monotonously related to the concentration of the fluid to be measured. Using the microfluidic concentration sensor chip can obtain the concentration of the fluid to be measured in the entire concentration range, and can realize full-scale high-precision measurement.

Description

Microfluid concentration sensor chip and microfluid characteristic measuring device

technical field

The invention relates to the technical field of microfluid measurement and control, in particular to a microfluid concentration sensor chip and a microfluid characteristic measuring device.

Background technique

There are many methods to measure liquid concentration, such as electrochemical method, the measuring device used is simple in structure, but electrochemical method relies on electrochemical reaction, which is only suitable for concentration measurement of high-concentration liquid, not suitable for microfluidics Measurement. The response is also very slow, which is not ideal for a feedback control loop. The Coriolis sensing device is also used in the measurement of fluid concentration. The measurement of the concentration of this device is based on the vibration of tiny pipelines. It is only suitable for the concentration measurement of low-concentration liquids, and its measurement process is relatively disturbed by the environment. The measurement dynamic range smaller. That is, the microfluidic concentration measurement device in the prior art has a small measurement range and low measurement accuracy, and cannot meet the high-precision measurement requirements in the entire concentration range.

Contents of the invention

The first object of the present invention is to provide a microfluidic concentration sensor chip to solve the technical problems of the concentration measuring device in the prior art with small measurement range and low measurement accuracy.

The microfluid concentration sensing chip provided by the present invention includes a substrate, the substrate is provided with a micro heater and at least two sensing elements, the distance between each sensing element and the micro heater is different, and the The sensing element is used to measure the thermal diffusivity of the fluid.

Further, the sensing element includes a first sensing element, a second sensing element and a third sensing element, and along the flow direction of the fluid, the micro heater, the first sensing element, the second sensing element The second sensing element and the third sensing element are arranged in sequence.

Further, the sensing element includes a first sensing element, a second sensing element, a fourth sensing element, and a fifth sensing element, and along the flow direction of the fluid, the micro heater, the first sensing element The sensing element and the second sensing element are arranged sequentially, the fourth sensing element and the first sensing element are arranged symmetrically with respect to the micro heater, and the fifth sensing element is arranged symmetrically with the second sensing element. The sensing element is arranged symmetrically with respect to the micro heater.

Further, the base body is also provided with a temperature measuring element, and the temperature measuring element is used to measure the temperature of the fluid to be measured.

The microfluid concentration sensing chip provided by the present invention can produce the following beneficial effects:

The microfluid concentration sensing chip provided by the invention measures the thermal diffusivity of the fluid to be measured through the thermal sensing principle. Since when the fluid to be measured is static, the thermal diffusivity has monotonicity with the increase of the concentration in the whole concentration range of 0-100%, so when using the microfluidic concentration sensor chip to measure the concentration, first make the micro heater The sensing surface of the sensing element is in contact with the static fluid to be measured, and then a modulated heat wave, such as a sinusoidal heat wave, is applied to the micro-heater, and the thermal diffusivity of the fluid to be measured is measured by the sensing element. Since the microfluid concentration sensing chip provided by the present invention can measure the thermal diffusivity of any concentration liquid, the concentration of the fluid to be measured in the entire concentration range can be obtained by using the microfluid concentration sensing chip provided by the present invention. Moreover, in the microfluidic concentration sensor chip, the distances from the multiple sensing elements to the microheater are different, so they can be calibrated with each other, thereby eliminating the influence of environmental factors on the measurement results, and the microfluidic concentration sensor The chip can realize high-precision full-scale measurement.

The second object of the present invention is to provide a microfluidic characteristic measuring device to solve the technical problems of the concentration measuring device in the prior art with small measurement range and low measurement accuracy.

The microfluid characteristic measuring device provided by the present invention includes a measuring body and the microfluid concentration sensor chip, the measuring body is provided with a fluid channel, the channel wall of the fluid channel is provided with a measuring chamber, and the measuring chamber The chamber communicates with the fluid channel; the microfluid concentration sensor chip is arranged on the wall of the channel, and the sensing surface of the microfluid concentration sensor chip is located in the measurement chamber for measuring the flow in the measurement chamber. A thermal diffusivity of the fluid in the chamber that is monotonically related to the concentration of the fluid to be measured.

Further, the distance between the sensing surface of the microfluidic concentration sensor chip and the inner surface of the channel wall is greater than or equal to 1mm and less than or equal to 5mm.

Further, the measurement chamber is located at the top of the fluid channel.

Further, the channel wall is also provided with a first accommodating chamber, the first accommodating chamber is located outside the measurement chamber and communicated with the measurement chamber, and the microfluid concentration sensor chip is arranged on Inside the first containing chamber.

Further, the channel wall is also provided with a second accommodating chamber, and the second accommodating chamber communicates with the fluid channel; the microfluidic characteristic measurement device also includes a microfluidic flow sensor chip, and the microfluidic The flow sensing chip has the same structure as the microfluid concentration sensing chip, the microfluid flow sensing chip is arranged in the second accommodation chamber, and the sensing surface of the microfluid flow sensing chip extends into the In the fluid channel, it is used to measure the flow rate of the fluid flowing through the fluid channel.

Further, along the flow direction of the fluid, the second accommodation chamber is located upstream of the first accommodation chamber.

Further, both the liquid inlet and the liquid outlet of the measurement body are provided with microfluidic joints.

Further, the microfluidic characteristic measurement device also includes a circuit board and a housing, the circuit board is fixedly arranged on the measurement body, the microfluid concentration sensing chip is connected to the circuit board, the measurement body and its The microfluid concentration sensing chip and the circuit board are all arranged in the housing, and the electrical interface of the circuit board and the liquid inlet and outlet of the measurement body are all extended to the outside the shell.

Further, the protection level of the casing is not lower than IP67.

The microfluidic characteristic measuring device provided by the present invention can produce the following beneficial effects:

The microfluid characteristic measuring device provided by the present invention includes the above-mentioned microfluid concentration sensing chip, so the microfluid characteristic measuring device has all the beneficial effects of the above microfluid concentration sensing chip, which will not be repeated here. As for the measuring body of the microfluidic characteristic measuring device provided by the present invention, it provides a fluid channel for the flow of the fluid to be tested. Of course, the fluid to be tested can also be filled with the fluid channel statically. The measurement chamber provided on the channel wall of the fluid channel enables the sensing surface of the microfluidic concentration sensor chip to not be in direct contact with the fluid velocity field in the fluid channel, so that the thermal diffusivity can be prevented from being affected by the flow of the fluid to be measured, Furthermore, the concentration of the fluid to be measured can be accurately measured, that is, the measurement body provides a measurement environment for accurately measuring the concentration of the fluid to be measured.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is a structural schematic diagram of one of the microfluidic concentration sensing chips provided by the embodiment of the present invention;

Fig. 2 is a schematic structural diagram of the second microfluidic concentration sensing chip provided by the embodiment of the present invention;

3 is a schematic structural view of the measurement body of the microfluidic characteristic measurement device provided by the embodiment of the present invention;

4 is a cross-sectional view of the assembly structure of the measurement body and the concentration sensor chip of the microfluidic characteristic measurement device provided by the embodiment of the present invention;

5 is a cross-sectional view of the assembly structure of the measurement body, the concentration sensor chip and the flow sensor chip of the microfluidic characteristic measurement device provided by the embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a microfluidic characteristic measuring device provided by an embodiment of the present invention;

7 is a schematic diagram of an exploded structure of a microfluidic characteristic measuring device provided by an embodiment of the present invention;

8 is one of the fitting relationship curves between the output results and the concentration of the microfluidic microfluidic concentration sensor chip provided by the embodiment of the present invention;

FIG. 9 is the second fitting relationship curve between the output result and the concentration of the microfluidic concentration sensor chip provided by the embodiment of the present invention.

Explanation of reference signs:

100-microfluid concentration sensing chip; 110-substrate; 120-micro heater; 130-first sensing element; 140-second sensing element; 150-third sensing element; 160-temperature measuring element; 170 - the fourth sensing chip; 180 - the fifth sensing chip;

200-microfluid flow sensor chip;

300-measurement main body; 310-fluid channel; 320-measurement chamber; 330-first containing chamber; 340-liquid inlet; 350-liquid outlet; 360-second containing chamber;

410-first circuit board; 415-first screw; 420-second circuit board; 425-second screw; 430-electrical interface; 435-fixing nut; 441-first sealing ring; 442-second sealing ring; 443-the third sealing ring; 444-the fourth sealing ring; 450-the housing; 451-the first housing; 452-the third screw; 453-the second housing; 454-the fourth screw.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The microfluid concentration sensing chip 100 provided in this embodiment is manufactured by a silicon-based micromachining manufacturing process. Microfluidic Concentration. As shown in Figure 1, the microfluid concentration sensor chip 100 includes a substrate 110, the substrate 110 is provided with a micro heater 120 and at least two sensing elements, the distance between each sensing element and the micro heater 120 is different, and the sensor The sensing element is used to measure the thermal diffusivity of the fluid.

The microfluid concentration sensing chip 100 provided in this embodiment measures the thermal diffusivity of the fluid to be measured through the thermal sensing principle. Since when the fluid to be measured is static, the thermal diffusivity is monotonic with the increase of the concentration in the entire concentration range of 0-100%, so when using the microfluidic concentration sensor chip 100 to measure the concentration, firstly make the microfluidic The sensing surface of the micro-heater 120 and the sensing element is in contact with the static fluid to be measured, and then a modulated heat wave, such as a sinusoidal heat wave, is applied to the micro-heater 120, and the thermal diffusivity of the fluid to be measured is measured by the sensing element. Since the microfluid concentration sensing chip 100 provided in this embodiment can measure the thermal diffusivity of any concentration liquid, the microfluid concentration sensing chip 100 provided in this embodiment can obtain the concentration range of the fluid to be measured in the entire concentration range. concentration within. Moreover, in the microfluid concentration sensing chip 100, the distances from the plurality of sensing elements to the micro heater 120 are different, so they can be calibrated with each other, thereby eliminating the influence of environmental factors on the measurement results, and the microfluid concentration The measurement accuracy of the sensor chip 100 is also high, that is, the microfluid concentration sensor chip 100 can realize high-precision full-scale measurement.

Here, the measurement principle of the microfluid concentration sensor chip 100 is introduced as follows:

Under the setting form of the micro heater 120 and the sensing element of the microfluidic concentration sensor chip 100 provided in this embodiment, the flow velocity V related to the temperature-time (T, t) transient depends on the thermal diffusivity D and the forced Convection equation:

It can be seen from the above formula that when the fluid is static, that is, V=0, if the microfluid concentration sensor chip 100 is placed in the measurement chamber 320 where the fluid can always remain static, the thermal diffusivity of the fluid can be measured. Thermal diffusivity is directly related to fluid properties such as concentration. By comparing and calibrating the measured thermal diffusivity with the standard value in advance, the concentration of the liquid to be measured can be obtained by measuring the thermal diffusivity of the liquid to be measured. It is especially effective when two fluids are mixed, for example, in methanol fuel cell applications, methanol is mixed with water; in addition, the concentration of urea in diesel engine exhaust gas treatment fluid is critical to the nitrogen and oxygen removal efficiency, so the method provided in this example can also be used The microfluidic concentration sensor chip 100 measures the concentration of urea.

Fig. 8 shows the relation curve of the thermal diffusivity and the concentration of the methanol melt obtained from the microfluidic concentration sensor chip 100, as shown in Fig. 8, the relation of thermal diffusivity and concentration can be used in the full dynamic concentration range with the third order Polynomial best fit. And most liquids, such as isopropanol and water-soluble urea, etc., can also use the microfluidic concentration sensor chip 100 provided in this embodiment for concentration measurement. Also, in some applications, such as diesel engine exhaust fluid, since only a limited concentration range is meaningful, the fit can be reduced to a linear function, as shown in Figure 9, which can significantly reduce the calibration cost.

Specifically, in this embodiment, the substrate 110 of the microfluid concentration sensing chip 100 can be made of glass; the micro heater 120 and the sensing element are both thermistors, preferably made of a stable metal with high temperature thermal conductivity (such as platinum or nickel) or CMOS (Complementary Metal Oxide Semiconductor, Complementary Metal Oxide Semiconductor) compatible materials (such as doped polysilicon), and each thermistor has a narrow line width, preferably within 4 μm in order to obtain faster Thermal response and higher time resolution; in addition, a thermal insulation pad can be provided between the micro heater 120 and the sensing element and the substrate 110, such as a parylene film with a thickness of 7-20 μm, preferably a thickness of 15 μm; In addition, the micro-heater 120 and the sensing surface of the sensing element, that is, the interface layer, can be a low-stress silicon nitride and silicon oxide composite film with a thickness of micrometers.

Specifically, in this embodiment, as shown in FIG. 1 , the sensing element includes a first sensing element 130, a second sensing element 140 and a third sensing element 150, and along the flow direction of the fluid, the micro heater 120, The first sensing element 130 , the second sensing element 140 and the third sensing element 150 are arranged in sequence.

Preferably, the distance from the second sensing element 140 and the third sensing element 150 to the micro heater 120 is a non-integer multiple of the distance from the first sensing element 120 to the micro heater 120 .

More specifically, the distance between the first sensing element 130 and the micro heater 120 ranges from 20 to 80 μm, preferably 40 to 60 μm; the distance between the second sensing element 140 and the micro heater 120 ranges from 60-120 μm, preferably 80-100 μm.

This embodiment also provides another structure of the microfluidic concentration sensing chip. As shown in FIG. Five sensing elements 180, and along the flow direction of the fluid, the micro heater 120, the first sensing element 130 and the second sensing element 140 are arranged in sequence, and the fourth sensing element 170 and the first sensing element 130 are connected to the micro heater 120 is arranged symmetrically, and the fifth sensing element 180 and the second sensing element 140 are arranged symmetrically with respect to the micro heater 120 . Because the heat conduction is usually uniform in all directions, symmetrically setting the sensing elements can increase the strength of the received signal and improve the sensitivity of the measurement.

Specifically, in this embodiment, as shown in FIG. 1 , the base body 110 is also provided with a temperature measuring element 160 for measuring the temperature of the fluid to be measured. Because the concentration of the fluid is very sensitive to temperature, the temperature data of the fluid is very critical to the measurement. In this embodiment, the heating scheme of the micro heater 120 can be better controlled by setting the temperature measurement element 160 to measure the temperature of the fluid to be measured.

Preferably, the temperature measuring element 160 is also a thermistor, and is made of the same material as each sensing element, so that it is convenient for management during the calibration process.

This embodiment also provides a microfluidic characteristic measurement device, as shown in Figure 3 and Figure 4, the microfluidic characteristic measurement device includes a measurement body 300 and the above-mentioned microfluid concentration sensor chip 100, the measurement body 300 is provided with a fluid channel 310, the channel wall of the fluid channel 310 is provided with a measurement chamber 320, and the measurement chamber 320 communicates with the fluid channel 310; the microfluid concentration sensing chip 100 is arranged on the channel wall, and the sensing surface of the microfluid concentration sensing chip 100 is located on The measurement chamber 320 is used to measure the thermal diffusivity of the fluid flowing into the measurement chamber 320, and the thermal diffusivity is monotonously related to the concentration of the fluid to be measured.

The microfluid characteristic measuring device provided in this embodiment includes the above-mentioned microfluid concentration sensor chip 100, so the microfluid characteristic measuring device has all the beneficial effects of the above-mentioned microfluid concentration sensor chip 100, and will not be repeated here. . As for the measurement body 300 of the microfluidic property measurement device provided in this embodiment, it provides a fluid channel 310 for the fluid to be measured to flow through. Of course, the fluid to be measured can also fill the fluid channel 310 statically. The measurement chamber 320 arranged on the channel wall of the fluid channel 310 enables the sensing surface of the microfluid concentration sensor chip 100 to not be in direct contact with the fluid velocity field in the fluid channel 310, so that the thermal diffusivity can be protected from the fluid to be measured. Influenced by the flow, the concentration of the fluid to be measured can be accurately measured, that is, the measurement body 300 provides a measurement environment for accurately measuring the concentration of the fluid to be measured.

Specifically, in this embodiment, as shown in FIG. 4 , the distance between the sensing surface of the microfluid concentration sensor chip 100 and the inner surface of the channel wall is greater than or equal to 1 mm and less than or equal to 5 mm. With this arrangement, the exchange efficiency of the fluid in contact with the sensing surface of the microfluid concentration sensor chip 100 is high, and the concentration update is relatively timely, thereby ensuring measurement accuracy.

More specifically, the distance between the sensing surface of the microfluidic concentration sensor chip 100 and the inner surface of the channel wall is greater than or equal to 1 mm and less than or equal to 2 mm.

Specifically, in this embodiment, as shown in FIGS. 3 and 4 , the measurement chamber 320 is located at the top of the fluid channel 310 . With such arrangement, the concentration exchange between the fluid in the measurement chamber 320 and the fluid in the fluid channel 310 is more timely, so that the accuracy of the measurement result is also higher.

Specifically, in this embodiment, as shown in FIGS. 3 and 4 , the channel wall is further provided with a first accommodating chamber 330 , the first accommodating chamber 330 is located outside the measurement chamber 320 and communicates with the measurement chamber 320 , the microfluid concentration sensor chip 100 is disposed in the first containing chamber 330 . The first accommodation chamber 330 provides an installation space for the microfluid concentration sensing chip 100, which is conducive to improving the installation firmness of the microfluid concentration sensing chip 100, and compared with directly installing the microfluid concentration sensing chip 100 on the channel wall. In addition, with such arrangement, the side wall of the first containing chamber 330 also plays a protective role for the microfluid concentration sensing chip 100 .

Specifically, in this embodiment, as shown in FIG. 5 , the channel wall can also be provided with a second accommodation chamber 360, and the second accommodation chamber 360 communicates with the fluid channel 310; the microfluidic characteristic measurement device also includes a microfluidic flow sensor The sensing chip 200, the microfluid flow sensing chip 200 has the same structure as the microfluid concentration sensing chip 100, the microfluid flow sensing chip 200 is arranged in the second containing chamber 360, and the sensing of the microfluid flow sensing chip 200 The surface protrudes into the fluid channel 310 for measuring the flow rate of fluid flowing through the fluid channel 310 .

Specifically, in this embodiment, the microfluid flow sensor chip 200 has a micro heater and at least two independent thermistors located downstream of the micro heater. Fluid concentration is not relevant.

From equation (1), it can be seen that if there is only one thermistor downstream, the measured fluid flow rate will always be related to the thermal properties of the fluid, so when the fluid properties (such as concentration) change, the measured flow rate will also change. However, when the two thermistors are at different distances di from the micro heater 120, each thermistor will sense a different heat value by measuring the heat conduction time difference and heat conduction magnitude. By solving the equation for each thermistor measurement, the dynamic unknown and measurement-dependent thermal diffusivity can be eliminated, and the flow velocity and mass flow in the fluid channel 310 can be obtained independent of the fluid properties:

For flowing media that may have different fluid properties (eg, concentrations), the ability to obtain flow rates independent of fluid properties is critical. Otherwise, the fluid flow in the monitored process will have great uncertainty, which is not good for the control process. The third sensing element 150 allows measurement of a large dynamic range, such as distances where heat transfer would be limited at low speeds of flow, requiring the thermistor to be placed at a short distance from the microheater, whereas at high speeds of flow, heat transfer would be limited. Large distances can be achieved, but resolution at short distances may not be resolved. Therefore, combining these thermistors at different distances will not only help de-characterize the fluid, but will also provide a better dynamic range for fluid flow measurement.

Specifically, in this embodiment, the microfluidic flow sensor chip 200 protrudes into the fluid channel 310, and the depth immersed in the fluid is less than 2 mm, preferably, the depth of immersion is less than 1 mm, so that when the fluid flows through the sensor chip Boundary layer conditions can be maintained.

Specifically, in this embodiment, as shown in FIG. 5 , along the flow direction of the fluid, the second accommodation chamber 360 is located upstream of the first accommodation chamber 330 . Such setting can effectively prevent the flow distribution from being affected by the space for fluid concentration exchange, that is, the measurement chamber 320 , thereby ensuring the accuracy of flow measurement.

Specifically, in this embodiment, as shown in FIG. 3 , both the liquid inlet 340 and the liquid outlet 350 of the measurement body 300 are provided with microfluidic joints.

More specifically, in this embodiment, as shown in FIG. 3 , both the liquid inlet end 340 and the liquid outlet end 350 are provided with an internal thread structure, which is convenient for adapting to other types of connectors. At the same time, the internal thread structure is also convenient for preventing Leak seal.

More specifically, in this embodiment, the material of the measurement body 300 is preferably a biochemically inert material with good fluid compatibility, such as PEEK polyether ether ketone, polytetrafluoroethylene or stainless steel.

Specifically, in this embodiment, as shown in FIG. 6 and FIG. 7, the microfluidic characteristic measurement device also includes a circuit board and a housing 450, the circuit board is fixedly arranged on the measurement body 300, and the microfluidic concentration sensor chip 100 is connected to the circuit board , the measurement body 300 and the microfluid concentration sensor chip 100 on it and the circuit board are all arranged in the casing 450, and the electrical interface 430 of the circuit board and the liquid inlet 340 and the liquid outlet 350 of the measurement body 300 are all extended to Shell 450 outside.

More specifically, in this embodiment, as shown in FIG. 7, the circuit board includes a first circuit board 410 and a second circuit board 420, wherein the first circuit board 410 is fixed to the measurement body 300 by first screws 415 for Acquiring, digitizing, amplifying and processing data from the sensing element packaged in the measuring body 300, and the first circuit board 410 may be provided with a data storage chip, in which data is stored within a programmable time interval, thereby ensuring data security; The second circuit board 420 is fixed to the measurement main body 300 by a second screw 425 for wired or wireless data communication.

In this embodiment, as shown in FIG. 7 , the electrical interface 430 is used for data cable connection, and also for device calibration, local data retrieval and device power supply.

Specifically, in this embodiment, the housing 450 includes a first shell 451 and a second shell 453 , which are fixedly connected by a third screw 452 and a fourth screw 454 after fastening.

In this embodiment, the protection level of the housing 450 is not lower than IP67. Preferably, the protection level of the housing 450 complies with IP68.

When assembling the microfluidic characteristic measurement device provided in this embodiment, after the circuit board is assembled to the measurement body 300, the first sealing ring 441 is used to seal the liquid inlet 340 and the first housing 451, and the second sealing ring 442 is used to seal the The liquid outlet 350 and the second housing 453 use the third sealing ring 443 to seal the electrical interface 430 and the second housing 453, and use the fourth sealing ring 444 to seal the first housing 451 and the second housing 453 to prevent liquid erosion.

In this embodiment, the electrical interface 430 can be provided with external threads, and after extending out of the second housing 453 , it can be fixed with a fixing nut 435 on the outside of the second housing 453 .

In summary, the microfluidic characteristic measurement device provided in this embodiment has a simple structure, but can be applied to the concentration measurement of various fluids, and the measurement device can provide high-precision and high-sensitivity full dynamic range concentration measurement, and the integrated The temperature measurement element 160 provides key information for precise process control, because the concentration measurement is affected by temperature; in addition, the measurement device is small in size, cost-effective, and the housing 450, circuit board and measurement body 300 are easy to disassemble and assemble, so it can also Configured as a one-time application.

In this embodiment, since the density of the fluid is related to the concentration of the fluid one by one, once the measuring device is calibrated, it can also measure the density of the fluid in addition to the functions of concentration measurement and flow measurement. Of course, it is also possible to directly calibrate the thermal diffusivity of a fluid of known density before the measurement. In addition, while measuring the flow rate, the flow rate can also be obtained simultaneously according to the relationship between the flow rate and the flow rate. Of course, in other embodiments of the present application, the microfluidic property measurement device can also integrate other sensor chips to further expand its functions.

It should be noted that the microfluid concentration sensor chip 100 and the microfluid characteristic measuring device provided in this embodiment are not only suitable for fluids containing two components, but also suitable for mixtures containing multiple fluids, as long as the fluid has a characteristic heat Diffusion rate uniform mixing is enough.

Finally, it should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (12)

1. A micro-flow liquid characteristic measuring device is characterized by comprising a measuring body (300) and a micro-flow liquid concentration sensing chip (100), wherein the measuring body (300) is provided with a fluid channel (310), the channel wall of the fluid channel (310) is provided with a measuring chamber (320), and the measuring chamber (320) is communicated with the fluid channel (310); the microfluidic liquid concentration sensing chip (100) comprises a substrate (110), wherein the substrate (110) is provided with a micro heater (120) and at least two sensing elements, the distances between the sensing elements and the micro heater (120) are different, and the sensing elements are used for measuring the thermal diffusivity of a fluid; the microfluidic liquid concentration sensing chip (100) is disposed on the channel wall, and a sensing surface of the microfluidic liquid concentration sensing chip (100) is located in the measurement chamber (320) and is configured to measure a thermal diffusivity of a fluid flowing into the measurement chamber (320), where the thermal diffusivity is monotonically related to a concentration of a fluid to be measured.

2. The microfluidic liquid property measurement device according to claim 1, wherein the sensing elements comprise a first sensing element (130), a second sensing element (140), and a third sensing element (150), and the micro-heater (120), the first sensing element (130), the second sensing element (140), and the third sensing element (150) are sequentially disposed in a flow direction of the fluid.

3. The microfluidic liquid property measurement device according to claim 1, wherein the sensing elements comprise a first sensing element (130), a second sensing element (140), and a fourth sensing element (170) and a fifth sensing element (180), and the micro-heater (120), the first sensing element (130), and the second sensing element (140) are sequentially disposed along a flow direction of the fluid, the fourth sensing element (170) and the first sensing element (130) are symmetrically disposed with respect to the micro-heater (120), and the fifth sensing element (180) and the second sensing element (140) are symmetrically disposed with respect to the micro-heater (120).

4. Microfluidic liquid property measurement device according to any of claims 1-3, wherein the base body (110) is further provided with a temperature measuring element (160), the temperature measuring element (160) being adapted to measure the temperature of the fluid to be measured.

5. The microfluidic liquid property measurement device according to claim 1, wherein a distance between a sensing surface of the microfluidic liquid concentration sensing chip (100) and an inner surface of the channel wall is greater than or equal to 1mm and less than or equal to 5mm.

6. The microfluidic liquid property measurement device according to claim 1, wherein the measurement chamber (320) is located at a top of the fluid channel (310).

7. The microfluidic liquid property measurement device according to any one of claims 1, 5 and 6, wherein the channel wall is further provided with a first accommodation chamber (330), the first accommodation chamber (330) is located outside the measurement chamber (320) and is communicated with the measurement chamber (320), and the microfluidic liquid concentration sensing chip (100) is arranged in the first accommodation chamber (330).

8. Microfluidic liquid property measurement device according to claim 7, wherein the channel wall is further provided with a second receiving chamber (360), the second receiving chamber (360) being in communication with the fluid channel (310); the device for measuring the characteristics of the microfluidic liquid further comprises a microfluidic liquid flow sensing chip (200), the microfluidic liquid flow sensing chip (200) and the microfluidic liquid concentration sensing chip (100) are identical in structure, the microfluidic liquid flow sensing chip (200) is arranged in the second accommodating chamber (360), and the sensing surface of the microfluidic liquid flow sensing chip (200) extends into the fluid channel (310) and is used for measuring the flow of fluid flowing through the fluid channel (310).

9. The microfluidic liquid property measurement device according to claim 8, wherein the second receiving chamber (360) is located upstream of the first receiving chamber (330) in a flow direction of the fluid.

10. Microfluidic liquid property measurement device according to any of claims 1, 5 and 6, characterized in that the inlet (340) and outlet (350) ends of the measurement body (300) are provided with microfluidic connections.

11. The microfluidic liquid property measurement device according to any one of claims 1, 5 and 6, further comprising a circuit board and a housing (450), wherein the circuit board is fixedly disposed on the measurement main body (300), the microfluidic liquid concentration sensing chip (100) is connected to the circuit board, the measurement main body (300) and the microfluidic liquid concentration sensing chip (100) thereon and the circuit board are disposed in the housing (450), and an electrical interface (430) of the circuit board and a liquid inlet end (340) and a liquid outlet end (350) of the measurement main body (300) extend out of the housing (450).

12. Microfluidic liquid property measurement device according to claim 11, wherein the protection rating of the housing (450) is not lower than IP67.

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