A method and device for measuring the viscosity of a trace liquid and the flow resistance of a microchannel

Abstract

The present invention relates to a measuring device for the viscosity of trace liquid and the flow resistance of microchannels, including a handheld portable measuring instrument internally integrated with a differential pressure sensor, a control chip, a power switch, two micro-pipe connection probes, and an LCD / LED screen. Among them, the differential pressure sensor is used to collect in real time the pressure difference of the liquid flow in the microchannel; the control chip is used to read, calculate, and output data; the two micro-pipe connection probes are used to insert into any position of the flow channel on the upper stream of the microfluidic chip to be measured to measure the pressure difference of the liquid flow between the two points; the LCD / LED screen is used for user control and display of the measurement results. The present invention has the following advantages: it simplifies the operation process and experimental equipment, can achieve miniaturization and portability, and innovatively solves the problem of precise measurement of the local flow resistance of any microfluidic chip with a silicone flow channel.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow resistance and viscosity measurement, and particularly to a method and device for measuring the viscosity of trace liquid and the flow resistance of microchannels. Background Art

[0002] Microfluidic chips are a science and technology mainly characterized by manipulating fluids in a micron-scale space, and have the ability to miniaturize the basic functions of laboratories such as biology and chemistry onto a chip of a few square centimeters, so they are also called laboratories on a chip. With the advantages of trace amount, precise controllability, real-time observation, etc., microfluidic technology has been increasingly widely used in the fields of biology, chemical engineering, etc. Many microfluidic applications require precise transmission of fluids along a channel network with a complex pattern. Therefore, accurately characterizing and measuring the hydraulic resistance of each channel segment and precisely controlling the fluid flow in the chip are of great significance. Flow resistance plays an important role in many applications, such as interface positioning, concentration distribution network, droplet generation in oil media, generation of different shear forces, etc.

[0003] The existing methods for measuring the flow resistance and viscosity of trace liquids mainly have the following defects:

[0004] First, most of the existing methods are complex to operate, cannot be used for finished microfluidic chips, and cannot detect the local flow resistance on the chip;

[0005] Second, they do not have the ability to measure the flow resistance at any local position of the microfluidic chip;

[0006] Third, the viscosity of trace liquids cannot be measured with traditional viscometers. Summary of the Invention

[0007] In order to overcome the above deficiencies of the prior art, the present invention provides a method and device for measuring the viscosity of trace liquids and the flow resistance of microchannels to solve the problems raised in the above background art.

[0008] To achieve the above object, the technical solution provided by the present invention is: a device for measuring the viscosity of trace liquids and the flow resistance of microchannels, including a handheld portable measuring instrument internally integrated with a differential pressure sensor, a control chip, a power switch, two micro-pipe connection probes, and an LCD / LED screen. Among them, the differential pressure sensor is used to collect the pressure difference of the liquid flow in the microchannel in real time; the control chip is used to read, calculate and output data; the two micro-pipe connection probes are used to insert into any position of the flow channel on the microfluidic chip to be measured to measure the pressure difference of the liquid flow between the two points; the LCD / LED screen is used for user control and display of the measurement results.

[0009] As an improvement: Two of the micro-pipes are connected to the probe. One end is connected to the differential pressure sensor inside the measuring instrument, and the other end is connected to the rigid pipe of the special metal pipe probe. According to the connection method differences of different models of differential pressure sensors, the rigid pipe needs to be filled with insulating oil or any non-corrosive liquid.

[0010] As an improvement: When the chip is bonded by soft silicone and hard material, a metal pipe with a V-shaped through-channel at the bottom is used; when the chip uses two layers of soft silicone for bonding, a metal pipe with a through-hole horizontally is used. When inserting the former into the metal pipe, there is no need to deliberately control the depth. Just insert it into the hard material to connect the micro-channel and the V-shaped channel. When inserting the latter into the metal pipe, the depth needs to be controlled so that the horizontal micro-channel is exactly connected to the horizontal through-hole at the lower end of the metal pipe.

[0011] As an improvement: A measuring method for the viscosity of a trace liquid and the flow resistance of a micro-channel includes the following steps:

[0012] Step 1: Measuring the flow resistance of any section of the micro-channel of the microfluidic chip: First, use a precision syringe pump to introduce liquid into the inlet of the microfluidic chip to be measured at a certain flow rate Q, so that the liquid fills the entire channel. Ensure that the connecting probe inside the measuring instrument is filled with insulating oil or other non-corrosive liquid. After the channel is filled with liquid, insert the metal probe into both ends of any channel to be measured on the chip to detect the pressure difference △P generated by the liquid passing through this section of the flow channel at a given flow rate. According to Poiseuille's law, the fluid resistance can be obtained. Adjust the measuring instrument to the flow resistance measurement mode, insert the two connecting probes into the position of the micro-channel to be measured, and input the known flow rate Q to obtain the flow resistance value of the micro-channel.

[0013] Step 2: Precise measurement of the viscosity of trace liquid: The measurement of liquid viscosity only adds a few steps on the basis of Step 1. Since the micro-channel in the microfluidic chip has a non-circular cross-section, the fluid resistance can be defined as In the formula, η is the liquid viscosity, L is the channel length, and r h is called the hydraulic radius, and is further defined as r h = 2A / P, where A is the cross-sectional area of the channel and P is the perimeter of the channel cross-section. After further simplification, the liquid viscosity calculation formula is Precise measurement of the viscosity of trace liquid can be achieved through the above method. When measuring the viscosity of trace liquid, adjust the measuring instrument to the viscosity measurement mode, introduce the liquid with the viscosity to be measured into the standard viscosity measurement chip with known flow resistance value and channel size parameters, and the viscosity value of the trace liquid can be obtained.

[0014] As an improvement: The measuring device in step 1 can be directly inserted into any part of the PDMS channel through a thin metal tube with an opening at the top, so that the channels on the chip are connected to the two inlets of the pressure sensor through connecting probes, effectively transmitting the liquid pressure to the pressure sensor, thereby measuring the pressure difference △P between any two positions in the microfluidic channel in real time.

[0015] As an improvement: The flow resistance and microchannel size parameters of the standard viscosity measurement chip in step 2 are both known. When used in conjunction with the measuring instrument, only the flow rate Q needs to be input, and the viscosity measurement can be completed without additional calibration.

[0016] After adopting the above technical solution, the beneficial effects of the present invention are as follows: This method simplifies the operation process and experimental equipment, and can achieve miniaturization and portability. Users only need to insert the connecting probe into any two points of the microfluidic channel of the microfluidic chip to accurately measure the flow resistance between these two points, without the need for pre-treatment of the existing microfluidic chip. This device innovatively solves the problem of precise measurement of local flow resistance of microfluidic chips. By using the Poiseuille formula for derivation and calculation, the error is small and the measurement is accurate. Only by introducing a small amount of liquid into the standardized viscosity measurement chip can the viscosity measurement be realized, making the liquid viscosity measurement more convenient, rapid, and requiring less liquid volume (a few microliters). Therefore, this method and device have important application prospects in the fields of biology and microfluidics. Description of the Drawings

[0017] Figure 1 It is a schematic connection structure diagram of a measuring device for the viscosity of a small amount of liquid and the flow resistance of a microchannel of the present invention;

[0018] Figure 2 It is a schematic external structure diagram of a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a small amount of liquid and the flow resistance of a microchannel of the present invention;

[0019] Figure 3 It is a schematic internal structure diagram of a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a small amount of liquid and the flow resistance of a microchannel of the present invention;

[0020] Figure 4 It is a schematic front view structure diagram of a metal probe with an elliptical through-hole for a double-layer soft silicone chip of a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a small amount of liquid and the flow resistance of a microchannel of the present invention;

[0021] Figure 5 It is a schematic side view structure diagram of a metal probe with an elliptical through-hole for a double-layer soft silicone chip of a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a small amount of liquid and the flow resistance of a microchannel of the present invention;

[0022] Figure 6It is a front view structural schematic diagram of a metal probe with a V-shaped through hole at the bottom for a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention, which is used for a layer of soft silicone chip and a layer of glass chip;

[0023] Figure 7 It is a side view structural schematic diagram of a metal probe with a V-shaped through hole at the bottom for a flow resistance and fluid viscosity measuring instrument of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention, which is used for a layer of soft silicone chip and a layer of glass chip;

[0024] Figure 8 It is a connection structural schematic diagram of the metal probe of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention with a layer of soft silicone chip and a layer of glass chip;

[0025] Figure 9 It is a flow schematic diagram in the microchannel after a double-layer soft silicone chip is connected to a probe of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention;

[0026] Figure 10 It is a flow schematic diagram in the microchannel after a double-layer soft silicone chip is connected to a probe of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention;

[0027] Figure 11 It is a flow schematic diagram in the microchannel after a layer of soft silicone chip and a layer of glass chip are connected to a probe of a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel of the present invention;

[0028] As shown in the figure: 1. Flow resistance and fluid viscosity measuring instrument; 2. Metal probe; 3. Precision injection pump; 4. Microfluidic chip to be measured; 5. Waste liquid outlet; 6. LCD / LED screen; 7. Power switch; 8. Pressure sensor; 9. Soft silicone chip; 10. Microchannel; 11. Glass chip; 12. Control chip. Detailed implementation manners

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Example: As Figures 1 to 6 shown, a measuring device for the viscosity of a trace amount of liquid and the flow resistance of a microchannel includes a portable handheld measuring instrument internally integrated with a differential pressure sensor, a control chip, a power switch, two micro-pipes connected to a probe, and an LCD / LED screen. Among them, the differential pressure sensor is used to collect the pressure difference of the liquid flow in the microchannel in real time; the control chip is used to read, calculate, and output data; the two micro-pipes connected to the probe are used to insert into any position of the flow channel on the microfluidic chip to be measured to measure the pressure difference of the liquid flow between the two points; the LCD / LED screen is used for user control and display of the measurement results.

[0031] Two of the micro-pipes connecting the probe are connected to the differential pressure sensor inside the measuring instrument at one end and the hard pipe of the special metal pipe probe at the other end. According to the differences in the connection methods of differential pressure sensors of different models, the hard pipe needs to be filled with insulating oil or any non-corrosive liquid.

[0032] When the chip is bonded by soft silicone and hard material, a metal pipe with a V-shaped through-channel at the bottom is used; when the chip uses two layers of soft silicone for bonding, a metal pipe with a through-hole horizontally is used. When inserting the former into the metal pipe, there is no need to deliberately control the depth, and directly inserting it into the hard material can achieve the connection between the micro-channel and the V-shaped channel. When inserting the latter into the metal pipe, the depth needs to be controlled so that the horizontal micro-channel is exactly connected to the horizontal through-hole at the lower end of the metal pipe.

[0033] A measuring method for a measuring device of the viscosity of a trace liquid and the flow resistance of a micro-channel includes the following steps:

[0034] Step 1: Measuring the flow resistance of any micro-channel of the microfluidic chip: First, use a precision syringe pump to introduce a liquid into the inlet of the microfluidic chip to be measured at a certain flow rate Q, so that the liquid fills the entire channel. Ensure that the connecting probe in the measuring instrument is filled with insulating oil or other non-corrosive liquid. After the channel is filled with the liquid, insert the metal probe into both ends of any channel to be measured on the chip, which is used to detect the pressure difference △P generated by the liquid passing through this flow channel at a given flow rate. According to Poiseuille's law, the fluid resistance can be obtained. Adjust the measuring instrument to the flow resistance measurement mode, insert the two connecting probes into the position of the micro-channel to be measured, and input the known flow rate Q to obtain the value of the micro-channel flow resistance.

[0035] Step 2: Precise measurement of the viscosity of trace liquid: The measurement of the liquid viscosity only adds a few steps on the basis of Step 1. Since the micro-channel in the microfluidic chip has a non-circular cross-section, the fluid resistance can be defined as In the formula, η is the liquid viscosity, L is the channel length, r h is called the hydraulic radius, and is further defined as r h = 2A / P, where A is the cross-sectional area of the channel and P is the perimeter of the channel cross-section. After further simplification, the liquid viscosity calculation formula is Through the above method, the precise measurement of the viscosity of trace liquid can be realized. When measuring the viscosity of trace liquid, adjust the measuring instrument to the viscosity measurement mode, introduce the liquid with the viscosity to be measured into the standard viscosity measurement chip with known flow resistance value and channel size parameters, and the viscosity value of this trace liquid can be obtained.

[0036] The measuring device in the above-mentioned step 1 can be directly inserted into any part of the PDMS flow channel through a thin metal tube with an opening at the top, so that the flow channel on the chip is connected to the two inlets of the pressure sensor through a connecting probe, effectively transmitting the liquid pressure to the pressure sensor, thereby measuring the pressure difference △P between any two positions in the microfluidic channel in real time.

[0037] The flow resistance and microchannel size parameters of the standard viscosity measurement chip in the above-mentioned step 2 are both known. When used in cooperation with the measuring instrument, only the flow rate Q needs to be input, and the viscosity measurement can be completed without additional calibration.

[0038] The above describes the present invention and its implementation manners. Such description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. All in all, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments to this technical solution without creative efforts without departing from the purpose of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A measuring device for the viscosity of trace liquid and the flow resistance of microchannels, characterized in that: it includes a handheld portable measuring instrument internally integrated with a differential pressure sensor, a control chip, a power switch, two microtube connection probes, and an LCD / LED screen. Among them, the differential pressure sensor is used to collect the pressure difference of the liquid flow in the microchannel in real time; the control chip is used to read, calculate and output data; the two microtube connection probes are used to insert into any position of the upper flow channel of the microfluidic chip to be measured to measure the pressure difference of the liquid flow between the two points; the LCD / LED screen is used for user control and display of the measurement results; The two microtube connection probes are rigid tubes with one end connected to the differential pressure sensor inside the measuring instrument and the other end connected to a special metal tube probe; The chip is bonded by soft silicone and hard material or two layers of soft silicone.

2. The measuring device for the viscosity of trace liquid and the flow resistance of microchannels according to claim 1, characterized in that: According to the connection method differences of different models of differential pressure sensors, the hard tube needs to be filled with insulating oil or any non-corrosive liquid.

3. The measuring device for the viscosity of trace liquid and the flow resistance of microchannels according to claim 1, characterized in that: When the chip is bonded by soft silicone and hard material, a metal tube with a V-shaped through-channel at the bottom is used; when the chip uses two layers of soft silicone bonding, a metal tube with a through-hole horizontally is used. When inserting the former into the metal tube, there is no need to deliberately control the depth, and directly inserting it into the hard material can realize the connection between the microchannel and the V-shaped channel. When inserting the latter into the metal tube, the depth needs to be controlled so that the horizontal microchannel is exactly connected to the horizontal through-hole at the lower end of the metal tube.

4. The measuring method of the measuring device for the viscosity of trace liquid and the flow resistance of microchannels according to claim 1, characterized in that: It includes the following steps: Step 1: Measurement of the flow resistance of any microchannel of the microfluidic chip: First, use a precision syringe pump to introduce liquid into the inlet of the microfluidic chip to be measured at a certain flow rate Q, so that the liquid fills the entire channel. Ensure that the connecting probe of the measuring instrument is filled with insulating oil or other non-corrosive liquid. After the channel is filled with liquid, insert the metal probe into both ends of any microchannel to be measured on the chip to detect the pressure difference △P generated by the liquid passing through this flow channel at a given flow rate. According to Poiseuille's law, the fluid resistance can be obtained. , adjust the measuring instrument to the flow resistance measurement mode, insert the two connecting probes into the position of the microchannel to be measured, and input the known flow rate Q to obtain the microchannel flow resistance value; Step 2: Precise measurement of the viscosity of a small amount of liquid: The measurement of the liquid viscosity only adds a few steps on the basis of Step 1. Since the microchannel in the microfluidic chip has a non-circular cross-section, the fluid resistance is defined as , in the formula is the liquid viscosity, L is the channel length, is called the hydraulic radius and is further defined as , where A is the cross-sectional area of the channel and P is the perimeter of the channel cross-section. After further simplification, the liquid viscosity calculation formula is . Through the above method, the precise measurement of the viscosity of a small amount of liquid is realized. When measuring the viscosity of a small amount of liquid, the measuring instrument is adjusted to the viscosity measurement mode. A liquid with the viscosity to be measured is introduced into a standard viscosity measurement chip with known flow resistance value and channel size parameters, and the viscosity value of the small amount of liquid can be obtained.

5. The measuring method of the measuring device for the viscosity of trace liquid and the flow resistance of microchannels according to claim 4, characterized in that: The measuring device in step 1 can be directly inserted into any part of the PDMS flow channel through a thin metal tube with an opening at the top, so that the flow channel on the chip is connected to the two inlets of the pressure sensor through the connection probe, effectively transferring the liquid pressure to the pressure sensor, thereby measuring the pressure difference △P between any two positions in the microfluidic channel in real time.

6. The measuring method of the measuring device for the viscosity of trace liquid and the flow resistance of microchannels according to claim 4, characterized in that: The flow resistance and microchannel size parameters of the standard viscosity measuring chip in step 2 are both known. When used in cooperation with the measuring instrument, only the flow rate Q needs to be input, and the viscosity measurement can be completed without additional calibration.

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