CN114100708A - Microfluid concentration sensing chip and microfluid characteristic measuring device - Google Patents
Microfluid concentration sensing chip and microfluid characteristic measuring device Download PDFInfo
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- CN114100708A CN114100708A CN202111344435.4A CN202111344435A CN114100708A CN 114100708 A CN114100708 A CN 114100708A CN 202111344435 A CN202111344435 A CN 202111344435A CN 114100708 A CN114100708 A CN 114100708A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
- B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
- B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
Abstract
The invention provides a microfluid concentration sensing chip and a microfluid characteristic measuring device, and relates to the technical field of microfluid measurement and control. The microfluid concentration sensing chip comprises a substrate, wherein the substrate is provided with a micro heater and at least two sensing elements, the distances between the sensing elements and the micro heater are different, and the sensing elements are used for measuring the thermal diffusivity of fluid. The microfluid characteristic measuring device comprises a measuring main body and a microfluid concentration sensing chip, wherein the measuring main body is provided with a fluid channel, a channel wall of the fluid channel is provided with a measuring chamber, and the measuring chamber is communicated with the fluid channel; the microfluid concentration sensing chip is arranged on the channel wall, and the sensing surface of the microfluid concentration sensing chip is positioned in the measuring chamber and used for measuring the thermal diffusivity of the fluid flowing into the measuring chamber, wherein the thermal diffusivity is monotonically related to the concentration of the fluid to be measured. The microfluid concentration sensing chip can obtain the concentration of the fluid to be measured in the whole concentration range, and can realize full-range high-precision measurement.
Description
Technical Field
The invention relates to the technical field of microfluid measurement and control, in particular to a microfluid concentration sensing chip and a microfluid characteristic measuring device.
Background
There are many methods for measuring the concentration of a liquid, such as an electrochemical method, which uses a simple measuring device, but the electrochemical method relies on an electrochemical reaction, and is suitable only for measuring the concentration of a high-concentration liquid, and is not suitable for measuring microfluid. The response is also very slow and is very undesirable for feedback control loops. The Coriolis sensing device is also applied to fluid concentration measurement, the device is based on the vibration of a micro pipeline for concentration measurement, is only suitable for concentration measurement of low-concentration liquid, and is relatively large in environmental interference in the measurement process and relatively small in measurement dynamic range. That is, the microfluid concentration measuring device in the prior art has small measuring range and low measuring precision, and cannot meet the high-precision measuring requirement in the whole concentration range.
Disclosure of Invention
The invention aims to provide a microfluidic concentration sensing chip to solve the technical problems of small measurement range and low measurement precision of a concentration measurement device in the prior art.
The invention provides a microfluidic concentration sensing chip which comprises a substrate, wherein the substrate is provided with a micro heater and at least two sensing elements, the distances between the sensing elements and the micro heater are different, and the sensing elements are used for measuring the thermal diffusivity of fluid.
Further, the sensing elements include a first sensing element, a second sensing element and a third sensing element, and the micro-heater, the first sensing element, the second sensing element and the third sensing element are sequentially arranged along the flow direction of the fluid.
Further, the sensing elements include a first sensing element, a second sensing element, a fourth sensing element and a fifth sensing element, and in the flow direction of the fluid, the micro-heater, the first sensing element and the second sensing element are sequentially disposed, the fourth sensing element and the first sensing element are symmetrically disposed with respect to the micro-heater, and the fifth sensing element and the second sensing element are symmetrically disposed with respect to the micro-heater.
Further, the base body is also provided with a temperature measuring element for measuring the temperature of the fluid to be measured.
The microfluid concentration sensing chip provided by the 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 by a heat sensing principle. Since the thermal diffusivity is monotonous with the increase of concentration in the whole concentration range of 0-100% when the fluid to be measured is in a static state, when the microfluidic concentration sensing chip is used for measuring the concentration, firstly, the micro heater and the sensing surface of the sensing element are contacted with the static fluid to be measured, then modulated thermal waves, such as sine thermal waves, are applied to the micro heater, and the thermal diffusivity of the fluid to be measured is measured by the sensing element. Because the microfluidic concentration sensing chip provided by the invention can measure the thermal diffusivity of liquid with any concentration, the concentration of the fluid to be measured in the whole concentration range can be obtained by using the microfluidic concentration sensing chip provided by the invention. In addition, in the microfluid concentration sensing chip, the distances from the plurality of sensing elements to the micro heater are different, so that the plurality of sensing elements can be calibrated mutually, the influence of environmental factors on a measurement result is eliminated, and the microfluid concentration sensing chip can realize high-precision full-range measurement.
The second objective of the present invention is to provide a microfluidic characteristic measurement device, so as to solve the technical problems of small measurement range and low measurement accuracy of the concentration measurement device in the prior art.
The invention provides a microfluid characteristic measuring device, which comprises a measuring main body and a microfluid concentration sensing chip, wherein the measuring main body is provided with a fluid channel, a channel wall of the fluid channel is provided with a measuring chamber, and the measuring chamber is communicated with the fluid channel; the microfluid concentration sensing chip is arranged on the channel wall, and the sensing surface of the microfluid concentration sensing chip is positioned in the measuring chamber and used for measuring the thermal diffusivity of the fluid flowing into the measuring chamber, wherein the thermal diffusivity is monotonically related to the concentration of the fluid to be measured.
Further, the distance between the sensing surface of the microfluidic concentration sensing chip and the inner surface of the channel wall is greater than or equal to 1mm and less than or equal to 5 mm.
Further, the measurement chamber is located at the top of the fluid channel.
Further, the channel wall is further provided with a first accommodating chamber, the first accommodating chamber is positioned outside the measuring chamber and is communicated with the measuring chamber, and the microfluidic concentration sensing chip is arranged in the first accommodating chamber.
Further, the channel wall is also provided with a second containing chamber which is communicated with the fluid channel; the microfluid characteristic measurement device further comprises a microfluid flow sensing chip, the microfluid flow sensing chip has the same structure as the microfluid concentration sensing chip, the microfluid flow sensing chip is arranged in the second accommodating cavity, and the sensing surface of the microfluid flow sensing chip extends into the fluid channel and is used for measuring the flow of fluid flowing through the fluid channel.
Further, the second receiving chamber is located upstream of the first receiving chamber in a flow direction of the fluid.
Furthermore, the liquid inlet end and the liquid outlet end of the measuring main body are both provided with a micro-fluidic joint.
Further, microfluid characteristic measurement device still includes circuit board and shell, the circuit board fixed set up in measure the main part, microfluid concentration sensing chip with the circuit board is connected, measure the main part and be equipped with microfluid concentration sensing chip with the circuit board all set up in the shell, just the electric interface of circuit board and the feed liquor end of measuring the main part all stretches out to outside the shell with play liquid end.
Further, the protection grade of the shell is not lower than IP 67.
The microfluid characteristic measuring device provided by the invention can produce the following beneficial effects:
the microfluidic characteristic measuring device provided by the invention comprises the microfluidic concentration sensing chip, so that the microfluidic characteristic measuring device has all the beneficial effects of the microfluidic concentration sensing chip, and is not repeated herein. As for the measurement body of the microfluidic property measurement apparatus provided by the present invention, it provides a fluid channel for the passage of the fluid to be measured, and of course, the fluid to be measured may be statically filled in the fluid channel. The measuring chamber is arranged on the channel wall of the fluid channel, so that the sensing surface of the microfluidic concentration sensing chip can not be in direct contact with the fluid velocity field in the fluid channel, the thermal diffusivity can be prevented from being influenced by the flow of the fluid to be measured, and the concentration of the liquid to be measured can be accurately measured, namely, the measuring body provides a measuring environment for accurately measuring the concentration of the fluid to be measured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural diagram of one of the microfluidic concentration sensing chips according to the embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a second microfluidic concentration sensor chip according to an embodiment of the present invention;
fig. 3 is a schematic structural view of a measurement body of the microfluidic characteristic measurement device according to the embodiment of the present invention;
fig. 4 is a sectional view showing an assembly structure of a measurement body and a concentration sensing chip of the microfluidic characteristic measurement apparatus according to the embodiment of the present invention;
fig. 5 is a sectional view showing an assembly structure of a measurement body of the microfluidic characteristic measurement device according to the embodiment of the present invention, and a concentration sensing chip and a flow sensing chip;
fig. 6 is a schematic structural view of a microfluidic characteristic measurement device according to an embodiment of the present invention;
fig. 7 is an exploded view of a microfluidic characteristic measurement device according to an embodiment of the present invention;
FIG. 8 is one of the fitted curves of the output result and the concentration of the microfluidic concentration sensor chip according to the embodiment of the present invention;
fig. 9 is a second fitting relationship curve of the output result and the concentration of the microfluidic concentration sensing chip according to the embodiment of the present invention.
Description of reference numerals:
100-microfluidic concentration sensing chip; 110-a substrate; 120-a micro-heater; 130-a first sensing element; 140-a second sensing element; 150-a third sensing element; 160-temperature measuring element; 170-a fourth sensor chip; 180-a fifth sensing chip;
200-microfluidic flow sensing chip;
300-a measurement subject; 310-a fluid channel; 320-a measurement chamber; 330-a first containment chamber; 340-liquid inlet end; 350-liquid outlet end; 360-a second containment chamber;
410-a first circuit board; 415-a first screw; 420-a second circuit board; 425-a second screw; 430 — an electrical interface; 435-fixing nuts; 441-a first sealing ring; 442-a second sealing ring; 443-third seal ring; 444-fourth sealing ring; 450-a housing; 451-a first housing; 452-a third screw; 453-a second housing; 454-fourth screw.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The microfluidic concentration sensing chip 100 provided in this embodiment is manufactured by a silicon-based Micro-machining manufacturing process, and is an MEMS (Micro-Electro-Mechanical System) sensing chip, and the concentration of the microfluidic to be measured is obtained by a thermal sensing principle. As shown in fig. 1, the microfluidic concentration sensing chip 100 includes a substrate 110, the substrate 110 is provided with a micro-heater 120 and at least two sensing elements, each of which has a different distance from the micro-heater 120, for measuring thermal diffusivity of a fluid.
The microfluidic concentration sensing chip 100 provided in this embodiment measures the thermal diffusivity of the fluid to be measured by using the thermal sensing principle. Since the thermal diffusivity is monotonous with an increase in concentration over the entire concentration range of 0 to 100% when the fluid to be measured is in a static state, when the microfluidic concentration sensing chip 100 is used to measure the concentration, the micro-heater 120 and the sensing surface of the sensing element are first brought into contact with the fluid to be measured in a static state, then a modulated thermal wave, for example, a sinusoidal thermal 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 microfluidic concentration sensing chip 100 provided in this embodiment can measure the thermal diffusivity of a liquid of any concentration, the microfluidic concentration sensing chip 100 provided in this embodiment can obtain the concentration of a fluid to be measured in the whole concentration range. In addition, in the microfluidic concentration sensing chip 100, the distances from the plurality of sensing elements to the micro-heater 120 are different, so that the sensing elements can be calibrated with each other, thereby eliminating the influence of environmental factors on the measurement result, and further the measurement accuracy of the microfluidic concentration sensing chip 100 is high, that is, the microfluidic concentration sensing chip 100 can realize high-accuracy full-scale measurement.
Here, the measurement principle of the microfluidic concentration sensing chip 100 is described as follows:
in the arrangement of the micro-heater 120 and the sensing element of the microfluidic concentration sensing chip 100 provided in this embodiment, the flow rate V associated with the temperature-time (T, T) transient depends on the thermal diffusivity D and the forced convection equation:
as can be seen from the above formula, when the fluid is in a static state, i.e., V is 0, if the microfluidic concentration sensing chip 100 is placed in the measurement chamber 320 where the fluid can be kept in a static state all the time, the thermal diffusivity of the fluid can be measured. The thermal diffusivity is directly related to fluid properties such as concentration, and the measured liquid concentration can be obtained by measuring the thermal diffusivity of the liquid to be measured correspondingly through comparing and calibrating the measured thermal diffusivity with a standard value in advance. The two fluids are particularly effective when mixed, for example in methanol fuel cell applications, where methanol is mixed with water; in addition, the concentration of urea in the exhaust gas treatment liquid of the diesel engine is important for the nitrogen oxide removal efficiency, so that the microfluidic concentration sensing chip 100 provided by the embodiment can also be used for measuring the concentration of urea.
Fig. 8 shows the thermal diffusivity of a methanol melt versus concentration curve obtained from the microfluidic concentration sensing chip 100, as shown in fig. 8, the thermal diffusivity versus concentration curve can be best fit with a third order polynomial over the full dynamic concentration range. Most liquids, such as isopropyl alcohol, water-soluble urea, etc., can also be used for concentration measurement by using the microfluidic concentration sensing chip 100 provided in this embodiment. Furthermore, in some applications, such as exhaust treatment fluids for diesel engines, because only a limited concentration range is meaningful, the fit can be reduced to a linear function, as shown in FIG. 9, which can significantly reduce calibration costs.
Specifically, in this embodiment, the substrate 110 of the microfluidic concentration sensor chip 100 may be made of glass; both the micro-heater 120 and the sensing element are thermistors, preferably made of a stable Metal (e.g., platinum or nickel) or CMOS (Complementary Metal Oxide Semiconductor) compatible material (e.g., doped polysilicon) with high temperature thermal conductivity, and each thermistor has a narrow line width, preferably within 4 μm, for faster thermal response and higher temporal resolution; furthermore, a thermal insulating mat, for example a parylene film with a thickness of 7-20 μm, preferably 15 μm, may be arranged between the micro-heater 120 and the sensor element and the substrate 110; in addition, the micro-heater 120 and the sensing surface of the sensing element, i.e., the interface layer, may be a low stress silicon nitride and silicon oxide composite film with a thickness of micron order.
Specifically, in the present embodiment, as shown in fig. 1, the sensing elements include 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 the flow direction of the fluid.
Preferably, the distance of the second and third sensing elements 140 and 150 to the micro-heater 120 is a non-integer multiple of the distance of 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 is 20 to 80 μm, and preferably 40 to 60 μm; the distance between the second sensing element 140 and the micro-heater 120 is in the range of 60 to 120 μm, and the preferable distance is in the range of 80 to 100 μm.
The present embodiment further provides another structure of a microfluidic concentration sensing chip, as shown in fig. 2, the sensing elements include a first sensing element 130, a second sensing element 140, 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 the 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. Since thermal conduction is generally isotropic, the symmetrically arranged sensing elements increase the received signal strength and improve the sensitivity of the measurement.
Specifically, in the present embodiment, as shown in fig. 1, the base 110 is further provided with a temperature measuring element 160, and the temperature measuring element 160 is used for measuring the temperature of the fluid to be measured. Since the concentration of the fluid is very sensitive to temperature, the temperature data of the fluid is very critical to the measurement, and the present embodiment can better control the heating scheme of the micro-heater 120 by setting the temperature measuring element 160 to measure the temperature of the fluid to be measured.
Preferably, the temperature measuring device 160 is also a thermistor and is made of the same material as the sensing devices, so as to facilitate management during calibration.
The present embodiment also provides a microfluidic characteristic measurement apparatus, as shown in fig. 3 and 4, the microfluidic characteristic measurement apparatus includes a measurement body 300 and the microfluidic concentration sensing chip 100 described above, the measurement body 300 is provided with a fluid channel 310, a channel wall of the fluid channel 310 is provided with a measurement chamber 320, and the measurement chamber 320 is communicated with the fluid channel 310; the microfluidic concentration sensing chip 100 is disposed on the channel wall, and a sensing surface of the microfluidic 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 the fluid to be measured.
The microfluidic characteristic measurement device provided in this embodiment includes the microfluidic concentration sensing chip 100, so that the microfluidic characteristic measurement device has all the advantages of the microfluidic concentration sensing chip 100, and details are not described herein. As for the measurement main body 300 of the microfluidic characteristic measurement apparatus provided in the present embodiment, it provides the fluid channel 310 for the circulation of the fluid to be measured, and of course, the fluid to be measured may statically fill the fluid channel 310. The measurement chamber 320 provided on the channel wall of the fluid channel 310 enables the sensing surface of the microfluidic concentration sensing chip 100 not to be in direct contact with the fluid velocity field in the fluid channel 310, so that the thermal diffusivity can be prevented from being affected by the flow of the fluid to be measured, and the concentration of the fluid to be measured can be accurately measured, i.e., the measurement body 300 provides a measurement environment for accurately measuring the concentration of the fluid to be measured.
Specifically, in the present embodiment, as shown in fig. 4, the distance between the sensing surface of the microfluidic concentration sensing chip 100 and the inner surface of the channel wall is greater than or equal to 1mm and less than or equal to 5 mm. With such an arrangement, the exchange efficiency of the fluid in contact with the sensing surface of the microfluidic concentration sensing chip 100 is high, and the concentration update is timely, so that the measurement accuracy can be ensured.
More specifically, the distance between the sensing surface of the microfluidic concentration sensing chip 100 and the inner surface of the channel wall is 1mm or more and 2mm or less.
Specifically, in the present embodiment, as shown in fig. 3 and 4, the measurement chamber 320 is located at the top of the fluid channel 310. So configured, the concentration of the fluid in the measurement chamber 320 and the fluid in the fluid channel 310 are exchanged more timely, and thus the accuracy of the measurement result is higher.
Specifically, in the present embodiment, as shown in fig. 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 is communicated with the measurement chamber 320, and the microfluidic concentration sensing chip 100 is disposed in the first accommodating chamber 330. The first accommodating chamber 330 provides an installation space for the microfluidic concentration sensing chip 100, which is beneficial to improving the installation firmness of the microfluidic concentration sensing chip 100, and in this way, the side wall of the first accommodating chamber 330 also plays a role in protecting the microfluidic concentration sensing chip 100, compared with the case that the microfluidic concentration sensing chip 100 is directly installed outside the channel wall.
Specifically, in the present embodiment, as shown in fig. 5, the channel wall may be further provided with a second accommodation chamber 360, and the second accommodation chamber 360 is communicated with the fluid channel 310; the microfluidic characteristic measurement device further includes a microfluidic flow rate sensing chip 200, the microfluidic flow rate sensing chip 200 has the same structure as the microfluidic concentration sensing chip 100, the microfluidic flow rate sensing chip 200 is disposed in the second accommodating chamber 360, and a sensing surface of the microfluidic flow rate sensing chip 200 extends into the fluid channel 310 for measuring a flow rate of the fluid flowing through the fluid channel 310.
In particular, in the present embodiment, the microfluidic flow sensing chip 200 has one micro-heater and at least two independent thermistors located downstream of the micro-heater, which configuration will allow a fluid flow to be obtained that is a pure volumetric flow, independent of the fluid concentration.
It can be seen from equation (1) that if there is only one thermistor downstream, the measured fluid flow rate will always be related to the thermal properties of the fluid, and therefore the measured flow rate will change as the fluid properties (e.g. concentration) change. However, when the distances di of the two thermistors to the micro-heater 120 are different, each thermistor will sense a different heat value by measuring a heat conduction time difference and a heat conduction amplitude. By solving the equation for each thermistor measurement, the dynamic unknown and measurement related thermal diffusivity can be eliminated and the flow velocity and mass flow in the fluid channel 310 can be obtained independently of the fluid properties:
for flowing media that may have different fluid properties (e.g., concentrations), the ability to achieve flow rates independent of the fluid properties is critical. Otherwise, the fluid flow in the monitored process will have a large uncertainty, which is detrimental to the control process. The third sensing element 150 allows for measurement of large dynamic ranges, such as distances where heat transfer will be limited at low flow rates, which requires the thermistor to be placed at a short distance from the micro-heater, while for high flow rates heat transfer can reach large distances, but resolution at short distances may not be addressed. Therefore, combining these thermistors at different distances not only helps to remove fluid characteristics, but will also provide better fluid flow measurement dynamic range.
Specifically, in the present embodiment, the microfluidic flow sensing chip 200 protrudes into the fluid channel 310 and is immersed into the fluid to a depth of less than 2mm, preferably less than 1mm, so as to maintain boundary layer conditions when the fluid flows through the sensing chip.
Specifically, in the present embodiment, continuing with fig. 5, in the direction of flow of the fluid, the second receiving chamber 360 is located upstream of the first receiving chamber 330. The arrangement can effectively avoid the influence of the space for exchanging the fluid concentration, namely the measurement chamber 320, on the flow distribution, thereby ensuring the accuracy of flow measurement.
Specifically, in the present embodiment, as shown in fig. 3, the inlet end 340 and the outlet end 350 of the measurement body 300 are provided with microfluidic connectors.
More specifically, in this embodiment, and as further shown in fig. 3, the inlet end 340 and the outlet end 350 are provided with internal threads to facilitate fitting to other types of connectors, and the internal threads also facilitate leak-proof sealing.
More specifically, in the present embodiment, the material of the measurement main body 300 is preferably a biochemical inert material, and the compatibility of the fluid is good, for example: PEEK, teflon, or stainless steel.
Specifically, in this embodiment, as shown in fig. 6 and 7, the microfluidic characteristic measurement apparatus further includes a circuit board and a housing 450, the circuit board is fixedly disposed on the measurement main body 300, the microfluidic concentration sensing chip 100 is connected to the circuit board, the measurement main body 300, the microfluidic concentration sensing chip 100 and the circuit board thereon are disposed in the housing 450, and the electrical interface 430 of the circuit board, and the liquid inlet end 340 and the liquid outlet end 350 of the measurement main body 300 extend out of the housing 450.
More specifically, in the present 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 a first screw 415 for acquiring, digitizing, amplifying and processing data from a sensing element packaged in the measurement body 300, and the first circuit board 410 may be provided with a data storage chip in which data is stored at programmable time intervals, so that data security can be ensured; the second circuit board 420 is fixed to the measurement body 300 by a second screw 425 for wired or wireless data communication.
In this embodiment, continuing with FIG. 7, electrical interface 430 is used for data cable connections, as well as for device calibration, local data retrieval, and device power.
Specifically, in this embodiment, the housing 450 includes a first housing 451 and a second housing 453 that are fastened together and then fixedly connected by a third screw 452 and a fourth screw 454.
In this embodiment, the protection rating of the housing 450 is not lower than IP 67. Preferably, the enclosure 450 is rated for protection in accordance with IP 68.
In the microfluidic characteristic measurement device according to this embodiment, when the circuit board is assembled to the measurement body 300, the inlet end 340 and the first case 451 are sealed by the first sealing ring 441, the outlet end 350 and the second case 453 are sealed by the second sealing ring 442, the electrical interface 430 and the second case 453 are sealed by the third sealing ring 443, and the first case 451 and the second case 453 are sealed by the fourth sealing ring 444 to prevent liquid corrosion.
In this embodiment, the electrical interface 430 may be externally threaded, and may be fixed by a fixing nut 435 on the outside of the second housing 453 after extending out of the second housing 453.
In summary, the microfluidic characteristic measurement device provided by the present 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, while the integrated temperature measurement element 160 provides critical information for precise process control, because the concentration measurement is affected by temperature; in addition, the measuring device is small in size, economical and efficient, and the shell 450, the circuit board, the measuring body 300 and the like are convenient to disassemble and assemble, so that the measuring device can be configured to be used for one time.
In this embodiment, since the density of the fluid is one-to-one correlated with the concentration of the fluid, once the measuring device is calibrated, the density of the fluid can be measured in addition to the functions of concentration measurement and flow measurement. Of course, the thermal diffusivity of a fluid of known density can also be calibrated directly before measurement. In addition, when the flow is measured, the flow velocity can be obtained simultaneously according to the relation between the flow velocity and the flow. Of course, in other embodiments of the present application, the microfluidic property measurement device may also integrate other sensing chips to further expand its functionality.
It should be noted that the microfluidic concentration sensing chip 100 and the microfluidic characteristic measurement 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 fluids are uniformly mixed at the characteristic thermal diffusivity.
Finally, it is further noted that, herein, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to 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 (13)
1. Microfluidic concentration sensing chip comprising a substrate (110), said substrate (110) being provided with a micro-heater (120) and at least two sensing elements, each of said sensing elements having a different distance to said micro-heater (120), said sensing elements being adapted to measure the thermal diffusivity of a fluid.
2. The microfluidic concentration sensing chip 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 along a flow direction of the fluid.
3. The microfluidic concentration sensing chip 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. The microfluidic concentration sensing chip according to any of claims 1-3, wherein the substrate (110) is further provided with a temperature measuring element (160), the temperature measuring element (160) being configured to measure the temperature of the fluid to be measured.
5. A microfluidic property measurement device comprising a measurement body (300) and the microfluidic concentration sensing chip (100) of any one of claims 1 to 4, wherein the measurement body (300) is provided with a fluid channel (310), a channel wall of the fluid channel (310) is provided with a measurement chamber (320), and the measurement chamber (320) is communicated with the fluid channel (310); the microfluidic concentration sensing chip (100) is disposed on the channel wall, and a sensing surface of the microfluidic concentration sensing chip (100) is located in the measurement chamber (320) and is used for measuring a thermal diffusivity of a fluid flowing into the measurement chamber (320), wherein the thermal diffusivity is monotonically related to a concentration of a fluid to be measured.
6. The microfluidic property measurement device according to claim 5, wherein a distance between a sensing surface of the microfluidic concentration sensing chip (100) and an inner surface of the channel wall is equal to or greater than 1mm and equal to or less than 5 mm.
7. The microfluidic property measurement device of claim 5, wherein the measurement chamber (320) is located at a top of the fluid channel (310).
8. The microfluidic property measurement device according to any one of claims 5 to 7, 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 communicates with the measurement chamber (320), and the microfluidic concentration sensing chip (100) is disposed in the first accommodation chamber (330).
9. The microfluidic property measurement device of claim 8, wherein the channel wall is further provided with a second receiving chamber (360), the second receiving chamber (360) being in communication with the fluidic channel (310); the microfluidic characteristic measurement device further comprises a microfluidic flow sensing chip (200), the microfluidic flow sensing chip (200) and the microfluidic concentration sensing chip (100) have the same structure, the microfluidic flow sensing chip (200) is arranged in the second accommodating chamber (360), and a sensing surface of the microfluidic 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).
10. The microfluidic property measurement device of claim 9, wherein the second containment chamber (360) is located upstream of the first containment chamber (330) in a flow direction of the fluid.
11. The microfluidic property measurement device according to any one of claims 5 to 7, wherein the inlet end (340) and the outlet end (350) of the measurement body (300) are each provided with a microfluidic joint.
12. The microfluidic property measurement device according to any one of claims 5 to 7, further comprising a circuit board and a housing (450), wherein the circuit board is fixedly disposed on the measurement body (300), the microfluidic concentration sensing chip (100) is connected to the circuit board, the measurement body (300) and the microfluidic 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 an inlet end (340) and an outlet end (350) of the measurement body (300) extend out of the housing (450).
13. The microfluidic property measurement device of claim 12, wherein the housing (450) has a protection rating of no less than IP 67.
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