Ultralow-heat-capacity heat-sensitive sensor and microfluid detection method

Abstract

The invention discloses an ultralow-heat-capacity heat-sensitive sensor and a microfluid detection method, and relates to the technical field of microfluid detection, and the ultralow-heat-capacity heat-sensitive sensor comprises a high-thermal-conductivity substrate, a plurality of thermistor units and upper and lower interconnected electrodes; each thermistor unit comprises a first temperature sensing resistance film, a second temperature sensing resistance film and a connecting film; the first temperature-sensing resistor film and the second temperature-sensing resistor film are in a water-drop-like shape and are provided with arc ends and tip ends. For each thermistor unit, a first through hole is formed in the arc end of each of the first temperature-sensing resistance film and the second temperature-sensing resistance film; a second through hole coaxial with the first through hole is formed in the high-thermal-conductivity substrate; the first through hole and the second through hole jointly form a vertical channel, and the upper and lower interconnected electrodes are embedded into the vertical channel; and the upper surfaces of the upper and lower interconnected electrodes and the upper surface of the thermistor unit are on the same horizontal line. According to the invention, high-sensitivity detection can be carried out on dynamic parameters of the microfluid in a micron or even smaller space.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microfluidic detection, and particularly relates to an ultra-low heat capacity thermal sensor and a microfluidic detection method. BACKGROUND

[0002] With the development of microfluidic technology to a more microscale (micron to nanometer level), the control precision of microfluidic behavior in a complex microspace is significantly improved, but the microscale effect (such as low Reynolds number flow, surface tension domination, rapid heat diffusion, etc.) poses a severe challenge to the accurate detection of microfluidic parameters. Flow rate, flow direction and temperature are the three key parameters of a microfluidic system, which directly affect the reaction efficiency, mass transfer and system stability, and the breakthrough of the detection technology is the core bottleneck to promote the development of microfluidic devices to integration and intelligence.

[0003] In related technologies, most microfluidic detection methods have the problems of insufficient resolution, low precision and large device size in micro fluid flow and embedded temperature detection, which are difficult to meet the current precision detection requirements.

[0004] Therefore, there is an urgent need for a technology that can detect the dynamic parameters of microfluids with high sensitivity in microns or even smaller spaces. SUMMARY

[0005] Therefore, the present application provides an ultra-low heat capacity thermal sensor and a microfluidic detection method to solve the technical problems in related technologies.

[0006] The present application provides an ultra-low heat capacity thermal sensor, comprising: a high-thermal-conductivity substrate, a plurality of thermistor units and an upper and lower interconnection electrode; the plurality of thermistor units are equally angularly spaced along the circumferential direction and distributed on the high-thermal-conductivity substrate with the geometric center of the high-thermal-conductivity substrate as the center; Each thermistor unit comprises a first temperature-sensing resistance film, a second temperature-sensing resistance film, and a connecting film for connecting the first temperature-sensing resistance film and the second temperature-sensing resistance film; the first temperature-sensing resistance film and the second temperature-sensing resistance film are both drop-like in shape and have a circular arc end and a sharp end; the sharp end of the first temperature-sensing resistance film is connected to the sharp end of the second temperature-sensing resistance film through the connecting film; For each thermistor unit, the circular arc end of the first temperature-sensing resistance film and the circular arc end of the second temperature-sensing resistance film are both provided with a first through hole; a second through hole coaxial with the first through hole is provided on the high-thermal-conductivity substrate; the first through hole and the second through hole jointly form a vertical channel, the upper and lower interconnection electrode is embedded in the vertical channel, and the outer wall of the upper and lower interconnection electrode and the inner wall of the vertical channel are in physical contact and electrically connected through conductive glue; the upper surface of the upper and lower interconnection electrode and the upper surface of the thermistor unit are on the same horizontal line.

[0007] In one alternative implementation, the plurality of thermistor units adopt an independent electrode type connection structure; the two tips of each thermistor unit are respectively spaced apart from one of the tips of the adjacent thermistor unit.

[0008] In one alternative implementation, the plurality of thermistor units adopt a shared electrode connection structure; the two tips of each thermistor unit are directly connected to one of the tips of the adjacent thermistor unit.

[0009] In one optional embodiment, the high thermal conductivity substrate is selected from rigid or flexible materials with a thermal conductivity greater than 50 W / (m·K); the first temperature-sensing resistor film, the second temperature-sensing resistor film, and the connecting film are made of the same material, and all of them have a temperature resistivity greater than 1×10⁻⁶. -3 ℃ -1 The choice of metallic or semiconductor materials should be consistent.

[0010] In one optional embodiment, the first temperature-sensitive resistor film, the second temperature-sensitive resistor film, and the connecting film have the same thickness, and each has a thickness of 5nm to 100nm; the number of thermistors is four.

[0011] In one optional embodiment, the upper surface of the high thermal conductivity substrate is deposited using step-by-step photolithography patterning to deposit a first temperature-sensitive resistor film, a second temperature-sensitive resistor film, and a connecting film, and the vertical vias are filled with conductive material through deep silicon etching to form upper and lower interconnect electrodes; the upper and lower interconnect electrodes are connected by leads using TSV or TGV processes.

[0012] Secondly, the present invention also provides a microfluidic detection method based on an ultra-low heat capacity thermistor, comprising: S1. Specify a thermistor unit in the independent electrode type connection structure, and apply a constant power pulse to the specified thermistor unit to raise the temperature of the specified thermistor unit to a level higher than the test operating temperature. Alternatively, in a shared electrode type connection structure, a constant power pulse is applied to each thermistor unit in sequence according to a set timing sequence, so that the temperature of the excited thermistor unit rises to a level higher than the test operating temperature. S2. Real-time acquisition of the voltage value of each thermistor unit, and calculation of the resistance change value of each thermistor unit at each moment based on the voltage value, generating a resistance response curve; When the voltage of the thermistor unit is higher than the reference voltage, the expression for the change in resistance is: When the voltage of the thermistor unit is lower than the reference voltage, the expression for the change in resistance is: wherein, is a resistance change value of the thermistor unit; is a voltage value corresponding to when the voltage of the thermistor unit is higher than the reference voltage; is a voltage value corresponding to when the voltage of the thermistor unit is lower than the reference voltage; is a reference voltage value; is a reference current value; S3, calculating the flow rate, flow direction and temperature of the microfluid based on the resistance change value and the resistance response start time of each thermistor unit, and calculating the angular resolution of the flow direction of the microfluid based on the number of thermistor units; the resistance response start time is determined based on the resistance response curve; The expression of the angular resolution of the flow direction of the microfluid is: wherein, A is the angular resolution, N is the number of thermistor units.

[0013] In an alternative embodiment, the calculation of the flow rate, flow direction and temperature of the microfluid based on the resistance change value and the resistance response start time of each thermistor unit comprises: judging the flow direction of the microfluid based on the resistance change value of each thermistor unit; calculating the flow rate of the microfluid based on the resistance response start time of each thermistor unit and the spacing between each thermistor unit; The expression of the flow rate is: calculating the temperature of the microfluid based on the resistance change value of each thermistor unit; The temperature of the microfluid is expressed as: wherein, and are the flow rate and temperature of the microfluid, respectively; is the thermistor unit and the spacing between the thermistor units ; is the resistance response start time of the thermistor unit ; is the resistance response start time of the thermistor unit ; is the resistance change value of the thermistor unit ; is the resistance change value of the thermistor unit ; to be a constant value related to the temperature coefficient of resistance; to be a test operating temperature.

[0014] The present application has the following advantages: The present application utilizes pulse voltage or pulse current to control the transient power of the thermistor unit, forms a temperature difference between the self-heating of the thermistor unit and the microfluid temperature, and integrates multiple thermistor units in a very small space to form an ultra-low heat capacity thermal sensor with two connection structures including independent electrode type and shared electrode type. The independent electrode type connection structure can provide higher response speed, and each upper and lower interconnection electrode can be measured and judged simultaneously. The shared electrode type connection structure makes full use of the advantages of the structure to achieve higher resolution in the same area. By judging the change of the transient temperature difference of the thermistor unit and the change of different thermistor positions, the speed and direction of the fluid are determined. At the same time, the pulse voltage / current excitation is used to realize low-power detection, reduce the self-heating of the ultra-low heat capacity thermal sensor, and detect the real-time microfluid temperature field change of the fluid.

[0015] The present application can detect the dynamic characteristics of the fluid with high sensitivity in a micron or even smaller space, realize real-time control of the flow direction, speed change and local temperature of the microfluid, and provide key support for complex microfluid systems. Not only does it improve the automation and intelligence of the microfluid system, but also provides reliable basic data support for high-precision biological, chemical and environmental analysis, and is suitable for microfluidic chips, microreactors and other applications that require precise fluid monitoring in a small space. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0017] Figure 1 is a structural schematic diagram of an ultra-low heat capacity thermal sensor according to an embodiment of the present application; Figure 2 is a top view of an ultra-low heat capacity thermal sensor according to an embodiment of the present application; Figure 3 is a top view of a thermistor unit according to an embodiment of the present application; Figure 4 is an independent electrode type connection structure diagram of a thermistor unit according to an embodiment of the present application; Figure 5is a shared electrode type connection structure diagram of a thermistor unit according to an embodiment of the present application; Figure 6 is a sensing surface cutting processing schematic diagram of an ultra-low heat capacity thermosensor according to an embodiment of the present application; Figure 7 is a flowchart schematic diagram of a microfluidic detection method according to an embodiment of the present application; Figure 8 is a resistance response curve diagram according to an embodiment of the present application; Figure 9 is a logic block diagram of a velocity vector of a microfluid according to an embodiment of the present application; Reference signs: 1, high thermal conductivity substrate; 2, thermistor unit; 21, first temperature sensing resistance film; 22, second temperature sensing resistance film; 23, connecting film; 211, circular arc end; 212, pointed end; 213, first through hole; 214, second through hole; 3, up and down interconnection electrode. DETAILED DESCRIPTION

[0018] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0019] In the description of the present application, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to simplify the description of the present application, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements, or it can be wireless connection, or it can be wired connection. 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.

[0021] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figures 1-3 As shown, the present invention provides an ultra-low thermal capacity thermistor sensor, comprising: a high thermal conductivity substrate 1, multiple thermistor units 2, and upper and lower interconnected electrodes 3; the multiple thermistor units 2 are all distributed at equal angular intervals on the high thermal conductivity substrate 1 with the geometric center of the high thermal conductivity substrate 1 as the center, along the circumferential direction. Each thermistor unit 2 includes a first temperature-sensitive resistive film 21, a second temperature-sensitive resistive film 22, and a connecting film 23 for connecting the first temperature-sensitive resistive film 21 and the second temperature-sensitive resistive film 22; both the first temperature-sensitive resistive film 21 and the second temperature-sensitive resistive film 22 are teardrop-shaped and have an arc end 211 and a tip 212; the tip 212 of the first temperature-sensitive resistive film is connected to the tip 212 of the second temperature-sensitive resistive film through the connecting film 23; For each thermistor unit 2, a first through hole 213 is provided at the arc end 211 of the first temperature-sensitive resistive film 21 and the second temperature-sensitive resistive film 22; a second through hole 214 coaxial with the first through hole 213 is provided on the high thermal conductivity substrate 1; the first through hole 213 and the second through hole 214 together form a vertical channel, and the upper and lower interconnecting electrodes 3 are embedded in the vertical channel, and the outer wall of the upper and lower interconnecting electrodes 3 and the inner wall of the vertical channel are physically contacted and electrically connected through conductive adhesive; the upper surface of the upper and lower interconnecting electrodes 3 is on the same horizontal line as the upper surface of the thermistor unit 2.

[0023] This invention transfers the upper and lower interconnecting electrodes 3 to the bottom of the high thermal conductivity substrate 1, achieving unobstructed temperature sensing plane, and the ultra-low heat capacity thermistor has high integration and is easily expandable into a high-density sensor array.

[0024] In one optional embodiment, the plurality of thermistor units 2 adopt an independent electrode type connection structure; the two tips 212 of each thermistor unit 2 are respectively spaced apart from one of the tips 212 of the adjacent thermistor unit 2.

[0025] For example, let's take four thermistor units as an example to illustrate, such as... Figure 4 As shown, Figure 1 An enlarged view within the dashed box shows four thermistor units labeled A, B, C, and D. For thermistor unit A, its two tips 212 are spaced apart from one tip of each of the adjacent thermistor units B and D. This method of spacing the tips between the thermistor units is an independent electrode type connection structure.

[0026] In an alternative embodiment, the plurality of thermistor units 2 adopt a shared electrode type connection structure; two tips 212 of each thermistor unit 2 are directly connected with one tip 212 of an adjacent thermistor unit 2 respectively.

[0027] For example, eight thermistor units are taken as an example for illustration, as shown in Figure 5 Fig. 8, the eight thermistor units are labeled as A, B, C, D, E, F, G and H respectively. For the thermistor unit A, two tips 212 thereof are directly connected with one tip 212 of the adjacent thermistor unit B and the thermistor unit D respectively. That is to say, each thermistor unit 2 is connected with its adjacent thermistor unit 2 in turn through the tips 212 in the first and last positions, which is the shared electrode type connection structure.

[0028] In an alternative embodiment, the high thermal conductivity substrate 1 is made of a material with a thermal conductivity greater than 50 W / (m·K), including but not limited to hard materials such as silicon substrate, glass substrate, or flexible materials such as polyimide, thermoplastic polyurethane elastomer, etc.

[0029] The first temperature-sensitive resistance film 21, the second temperature-sensitive resistance film 22 and the connecting film 23 are made of the same material, and are made of a metal material or a semiconductor material with a temperature resistance coefficient (TCR) greater than 1×10 -3 ℃ -1 . The metal material includes but is not limited to platinum (Pt), nickel (Ni), copper (Cu) and tungsten (W); the semiconductor material includes but is not limited to polycrystalline silicon (Poly-Si), amorphous silicon (a-Si) and metal oxide.

[0030] Preferably, the first temperature-sensitive resistance film 21, the second temperature-sensitive resistance film 22 and the connecting film 23 are all made of platinum (Pt).

[0031] In an alternative embodiment, the first temperature-sensitive resistance film 21, the second temperature-sensitive resistance film 22 and the connecting film 23 have the same thickness, and the thickness is 5 nm~100 nm; the number of thermistor units is four.

[0032] In an alternative embodiment, the upper surface of the high thermal conductivity substrate 1 is stepwise photoetching patterned to deposit the first temperature-sensitive resistance film, the second temperature-sensitive resistance film and the connecting film, and the vertical through hole is filled with conductive material to form upper and lower interconnection electrodes through deep silicon etching; the upper and lower interconnection electrodes are connected through TSV or TGV process.

[0033] Specifically, as shown in Figure 6 ​As shown, the ultra-low heat capacity thermal sensor is patterned by a step-by-step photolithography technology, platinum (Pt) is directly deposited on the high thermal conductivity substrate 1 as a temperature sensing resistance layer (first temperature sensing resistance film 21 + second temperature sensing resistance film 22 + connecting film 23), then deep silicon etching is performed to fill the vertical through hole with conductive material, and the lead electrode (i.e., the upper and lower interconnection electrodes 3) is connected to the bottom of the high thermal conductivity substrate 1 (i.e., the lower surface of the high thermal conductivity substrate 1), and the ultra-low heat capacity thermal sensor is cut into a single unit.

[0034] As shown in the formula (1), the present application also provides an ultra-low heat capacity thermal sensor-based microfluid detection method, which is suitable for real-time monitoring of fluid parameters in a small scale, and has important value in high-precision detection applications such as biomedical, chemical analysis and environmental monitoring. Figure 7

[0035] The method comprises: S1, in the independent electrode type connection structure, a thermistor unit is specified, and a constant power pulse is applied to the specified thermistor unit, so that the temperature of the specified thermistor unit is raised to be higher than the test working condition temperature; Or, in the shared electrode type connection structure, a constant power pulse is applied to each thermistor unit according to a set time sequence, so that the temperature of the excited thermistor unit is raised to be higher than the test working condition temperature.

[0036] Wherein, the constant power pulse can be applied to the thermistor unit by the pulse modulation module to realize voltage or current excitation. In the shared electrode type connection structure, the voltage needs to be strictly excited according to the set time sequence pulse and detected at the same time, and the resistance at the current time is calculated.

[0037] S2, the voltage value of each thermistor unit is collected in real time, and the resistance change value of each thermistor unit at each time is calculated according to the voltage value, and a resistance response curve is generated, as shown in the formula (2). Figure 8 When the voltage value of the thermistor unit is higher than the reference voltage, the expression of the resistance change is: When the voltage value of the thermistor unit is lower than the reference voltage, the expression of the resistance change is: Wherein, R is the resistance change value of the thermistor unit; V is the voltage value corresponding to when the voltage of the thermistor unit is higher than the reference voltage; V is the voltage value corresponding to when the voltage of the thermistor unit is lower than the reference voltage; V is the reference voltage value; I is the reference current value.​​

[0038] S3, calculating the flow rate, flow direction and temperature of the microfluid according to the resistance change value and resistance response start time of each thermistor unit, and calculating the angular resolution of the flow direction of the microfluid according to the number of thermistor units; the resistance response start time is determined based on the resistance response curve; The expression of the angular resolution of the flow direction of the microfluid is: Wherein, A is the angular resolution, N is the number of thermistor units.

[0039] The present application preheats one of the thermistor sensing units (as a micro heat source) in the form of pulse flow (given constant power) and higher than the test working condition temperature. Since the first temperature sensing resistance film, the second temperature sensing resistance film and the connecting film all have a linear relationship with temperature, the resistance increases with temperature rise and decreases with temperature drop. The quantitative control of temperature rise of the micro heat source can be realized by detecting the resistance value and resistance change value of the thermistor sensing unit. The remaining thermistor sensing units serve as heat perception. The flow rate, flow direction and temperature of the microfluid are calculated according to the resistance change value (resistance response amplitude) and resistance response time (different temperatures and directions of the microfluid will cause corresponding resistance response) of each thermistor unit, and the angular resolution of the flow direction of the microfluid is calculated according to the number of thermistor units.

[0040] In an alternative embodiment, calculating the flow rate, flow direction and temperature of the microfluid according to the resistance change value and resistance response start time of each thermistor unit, comprises: judging the flow direction of the microfluid according to the resistance change value of each thermistor unit; calculating the flow rate of the microfluid according to the resistance response start time of each thermistor unit and the spacing between each thermistor unit; The expression of the flow rate is: calculating the temperature of the microfluid according to the resistance change value of each thermistor unit; The temperature of the microfluid is expressed as: Wherein, and are the flow rate and temperature of the microfluid, respectively; is the number of thermistor units and the spacing between thermistor units ; is the resistance response start time of the thermistor unit ; the resistance response start time of the thermistor unit ; the resistance change value of the thermistor unit ; the resistance change value of the thermistor unit ; a constant value related to the resistance temperature coefficient; a test condition temperature.

[0041] As shown in Figure 9 , a super-low thermal capacity thermosensor with a shared electrode type connection structure or an independent electrode type connection structure having four thermistor units is described. When the thermistor unit A is a micro heat source and the temperature is slightly higher than the test condition temperature, at this time, the resistance change value of the thermistor unit C rises due to the heat dissipation of the micro fluid and the thermistor unit A (micro heat source), that is, , the resistance response is as shown in Figure 8 1. t 3. At the same time, the resistance values of the thermistor units D and B at the positions also change accordingly, but since the flow direction is parallel to the connection lines of the thermistor units A and C, the resistance values of the thermistor units D and B at the positions change almost consistently, that is, = , the resistance response is as shown in Figure 8 2. t At this time, the resistance value of the thermistor unit A decreases due to the heat dissipation of the micro fluid, and the resistance response is as shown in Figure 8 1. t

[0042] At this time, the flow rate of the micro fluid is: The temperature of the micro fluid is: wherein, and are the corresponding flow rate and temperature when the flow direction of the micro fluid is from the thermistor unit A to the thermistor unit C ; is the interval between the thermistor unit A and the thermistor unit C ; is the resistance response start time of the thermistor unit C ; is the resistance response start time of the thermistor unit A ; is the resistance change value of the thermistor unit D ; ​a resistance change value of the thermistor unit B a resistance temperature coefficient related constant value; a resistance temperature coefficient related constant value; a test condition temperature.

[0043] Preferably, the distance between the thermistor units D and B, and the distance between the thermistor units A and C are both 40 μm.

[0044] It should be noted that when setting the distance between the thermistor units, the distance should be less than the thermal diffusion characteristic length.

[0045] Although the embodiments of the present application have been described with reference to the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes are intended to fall within the scope of the present application defined by the appended claims.

Claims

1. An ultra-low heat capacity thermal sensor, characterized in that, The application relates to a super-low-heat-capacity thermal sensor, which comprises a high-heat-conducting substrate, a plurality of thermistor units and upper and lower interconnecting electrodes. Each thermistor unit comprises a first temperature-sensing resistance film, a second temperature-sensing resistance film and a connecting film for connecting the first temperature-sensing resistance film and the second temperature-sensing resistance film; the first temperature-sensing resistance film and the second temperature-sensing resistance film are both drop-like in shape and have arc ends and pointed ends; the pointed end of the first temperature-sensing resistance film is connected with the pointed end of the second temperature-sensing resistance film through the connecting film. For each thermistor unit, the arc ends of the first temperature-sensing resistance film and the second temperature-sensing resistance film are both provided with first through holes; second through holes coaxial with the first through holes are formed in the high-heat-conducting substrate; the first through holes and the second through holes jointly form a vertical channel, the upper and lower interconnecting electrodes are embedded in the vertical channel, and the outer wall of the upper and lower interconnecting electrodes is in physical contact and electrical connection with the inner wall of the vertical channel through conductive glue; the upper surface of the upper and lower interconnecting electrodes is on the same horizontal line as the upper surface of the thermistor unit. The plurality of thermistor units adopt an independent electrode type connection structure; the two pointed ends of each thermistor unit are arranged at intervals from one pointed end of an adjacent thermistor unit.

2. The ultra-low thermal mass thermal sensor of claim 1, wherein, 3. The super-low-heat-capacity thermal sensor according to claim 1, wherein the plurality of thermistor units adopt a shared electrode type connection structure; the two pointed ends of each thermistor unit are directly connected with one pointed end of an adjacent thermistor unit. The thicknesses of the first temperature-sensing resistance film, the second temperature-sensing resistance film and the connecting film are the same and are 5-100 nm; the number of the thermistors is four. The upper surface of the high-heat-conducting substrate is subjected to stepwise photoetching patterning to deposit the first temperature-sensing resistance film, the second temperature-sensing resistance film and the connecting film, and deep silicon etching is performed on the vertical through holes to fill the vertical through holes with conductive materials to form the upper and lower interconnecting electrodes; the upper and lower interconnecting electrodes are connected through a TSV or TGV process.

4. The ultra-low thermal mass thermal sensor of claim 1, wherein, The high-thermal-conductivity base is made of hard material or flexible material with thermal conductivity greater than 50 W / (m·K); the first temperature-sensing resistance film, the second temperature-sensing resistance film and the connecting film are made of the same material, and are made of metal material or semiconductor material with temperature resistance coefficient greater than 1×10 -3 ℃ -1 .

5. The ultra-low thermal mass thermal sensor of claim 3, wherein, The application further relates to a method for testing the super-low-heat-capacity thermal sensor.

6. The ultra-low thermal mass thermal sensor of claim 1, wherein, S1. In the independent electrode type connection structure, one thermistor unit is designated, and a constant power pulse is applied to the designated thermistor unit to make the temperature of the designated thermistor unit higher than the test working temperature; 7. A microfluidic detection method based on the ultra-low heat capacity thermal sensor according to any one of claims 1 to 6, characterized in that, Or, in the shared electrode type connection structure, a constant power pulse is applied to each thermistor unit according to a set time sequence to make the temperature of the excited thermistor unit higher than the test working temperature; S2. The voltage value of each thermistor unit is collected in real time, and the resistance change value of each thermistor unit at each moment is calculated according to the voltage value to generate a resistance response curve; When the voltage value of the thermistor unit is higher than the reference voltage, the expression of the resistance change is: When the voltage value of the thermistor unit is lower than the reference voltage, the expression of the resistance change is: ​ ​ wherein, is a resistance change value of the thermistor unit; is a voltage value corresponding to when the voltage of the thermistor unit is higher than the reference voltage; is a voltage value corresponding to when the voltage of the thermistor unit is lower than the reference voltage; is a reference voltage value; is a reference current value; S3, calculating the flow rate, flow direction and temperature of the microfluid according to the resistance change value and the resistance response starting time of each thermistor unit, and calculating the angular resolution of the flow direction of the microfluid according to the number of thermistor units; the resistance response starting time is determined based on the resistance response curve; The expression of the angular resolution of the flow direction of the microfluid is: wherein A is the angular resolution, N is the number of thermistor units.

8. The method of claim 7, wherein, The calculation of the flow rate, flow direction and temperature of the microfluid according to the resistance change value and the resistance response starting time of each thermistor unit comprises: Judging the flow direction of the microfluid according to the resistance change value of each thermistor unit; Calculating the flow rate of the microfluid according to the resistance response starting time of each thermistor unit and the spacing between each thermistor unit; The expression of the flow rate is: Calculating the temperature of the microfluid according to the resistance change value of each thermistor unit; The temperature of the microfluid is expressed as: wherein, and are the flow rate and temperature of the microfluid, respectively; is a thermistor unit and a thermistor unit is the distance between the thermistor unit is a thermistor unit is the resistance response start time of the thermistor unit is the resistance response start time of the thermistor unit is a thermistor unit is the resistance change value of the thermistor unit is a thermistor unit is the resistance change value of the thermistor unit is a thermistor unit is a constant value related to the resistance temperature coefficient; is the test working temperature.

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