A sweat collection and detection patch based on capillary microflow pump

Abstract

The present invention relates to a sweat collection and detection patch based on a capillary microflow pump, wherein the periphery of a PET film and a PDMS film are sealed and connected, and a sensor assembly includes a sweat marker detection sensor and a flow rate sensor, wherein a sweat marker detection sensor provided by a working electrode, a reference electrode and a counter electrode is formed on the PET film, and a flow rate sensor provided by an interdigitated electrode is also formed on the PET film, and an injection chamber is formed on the PDMS film, wherein the sweat marker detection sensor is facing the injection chamber to measure the marker of sweat, and a serpentine microcolumn array channel is formed on the PDMS film, and the flow rate sensor is facing the serpentine microcolumn array channel to measure the flow rate of sweat. According to the sweat collection and detection patch based on a capillary microflow pump of the present invention, a sensor integrating sweat metabolite detection and flow rate detection realizes multi-target detection, and can effectively detect the marker lactic acid and sweat flow rate in sweat at the same time.

Description

Technical Field

[0001] The present invention relates to sweat detection, and more particularly to a sweat collection and detection patch based on a capillary microflow pump. Background Art

[0002] Wearable sweat sensors have developed rapidly due to their great potential in non-invasive and continuous monitoring of physiological parameters. While developing rapidly, some major challenges remain to be addressed. Most wearable sweat sensors are in direct contact with the skin surface. If close contact cannot be formed, the secreted sweat is easy to evaporate or contaminate on the skin surface. In order to effectively collect and detect sweat, most of them currently integrate microfluidic chips with wearable sensors, which also raises the question of how sweat can efficiently enter and discharge from the microfluidic channel chamber.

[0003] Some have proposed a finger-driven microfluidic system that draws sweat from the epidermis into a microchamber by pressing the finger. However, these devices require additional pressing actions, which hinders real-time monitoring during use.

[0004] In addition, some methods install adsorbent polymers or hydrogels on the sample inlet and outlet. The capillary action and osmosis principle spontaneously drive the sweat flow. However, the sweat flow inside the microfluidic is determined by the porosity of the polymer material and the hydrophilicity of the hydrogel, which is difficult to control.

[0005] The sweat rate greatly affects the detection accuracy of the sensor and is also one of the important detection indicators. At present, there is a lack of an integrated self-driven patch that can effectively control the sweat flow rate and detect markers and flow rate in sweat. Summary of the invention

[0006] In order to solve the problem in the prior art that markers and flow rate in sweat cannot be detected simultaneously, the present invention provides a sweat collection and detection patch based on a capillary microflow pump.

[0007] According to the sweat collection and detection patch based on the capillary microflow pump of the present invention, it includes a PET film, a PDMS film, a sensor component and a serpentine micro-column array channel, wherein the periphery of the PET film and the PDMS film are sealed and connected, the sensor component includes a sweat marker detection sensor and a flow rate sensor, a sweat marker detection sensor provided by a working electrode, a reference electrode and a counter electrode is formed on the PET film, a flow rate sensor provided by an interdigitated electrode is also formed on the PET film, an injection chamber is formed on the PDMS film, the sweat marker detection sensor is facing the injection chamber to measure the markers of sweat, a serpentine micro-column array channel is formed on the PDMS film, and the flow rate sensor is facing the serpentine micro-column array channel to measure the flow rate of sweat.

[0008] Preferably, a capillary check valve is formed on the PDMS film and is located between the injection chamber and the serpentine micro-pillar array channel to prevent sweat from flowing back.

[0009] Preferably, the micropillars in the channels of the serpentine micropillar array have the same or different lengths and widths.

[0010] Preferably, the distances between adjacent micropillars in the serpentine micropillar array channels are the same or different.

[0011] Preferably, the working electrode is modified by TTF / CNT as an intermediary layer.

[0012] Preferably, a sweat inlet is formed on the PDMS film, and the working electrode is arranged directly corresponding to the inlet.

[0013] Preferably, a sweat outlet is formed on the PET film, and is arranged opposite to the liquid outlet chamber on the PDMS film.

[0014] Preferably, the sample inlet and / or the sample outlet has hydrogel and hydrophilic polymer materials to increase the efficiency of absorbing sweat.

[0015] Preferably, a plurality of chamber micro-columns serving as supports are arranged in the sample inlet chamber and / or the liquid outlet chamber.

[0016] Preferably, the sweat marker detection sensor and the flow rate sensor are connected to the electrochemical workstation via the electrode connections on the PET film.

[0017] The sweat collection and detection patch based on the capillary microfluidic pump according to the present invention is a simple and easy-to-make patch prepared by combining microfluidic technology, which integrates sensors for sweat metabolite detection and flow rate detection to achieve multi-target detection, and can effectively detect the marker lactic acid and sweat flow rate in sweat at the same time. The sweat marker detection sensor shows a good detection sensitivity (7.36μA / mM·cm 2 , R 2 =0.996), while the flow rate sensor can detect the detection range of 0-60μL / min. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic cross-sectional structure diagram of a sweat collection and detection patch based on a capillary microflow pump according to a preferred embodiment of the present invention;

[0019] Figure 2 yes Figure 1 perspective drawing;

[0020] Figure 3 A sensor assembly formed on a PET film is shown;

[0021] Figure 4The modification of the working electrode of the sweat marker detection sensor is shown;

[0022] Figure 5 The modification of the reference electrode of the sweat marker detection sensor is shown;

[0023] Figure 6 Shown is a serpentine micropillar array channel formed on a PDMS film;

[0024] Figure 7 This is a partial magnified image of the serpentine micropillar array channel;

[0025] Figure 8 Three channels are shown;

[0026] Fig. 9 The simulation results of three channels are compared.

[0027] Fig.10 The comparison of experimental results of two channels is shown;

[0028] Fig.11 This is the calibration result diagram of the flow rate sensor;

[0029] Fig.12 This is a graph showing the current response of the sweat marker detection sensor. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0031] like Figure 1 As shown, the sweat collection and detection patch based on the capillary microflow pump according to a preferred embodiment of the present invention comprises a PET film 10 and a PDMS film 20 connected by a peripheral seal, and the sealing area is as shown in FIG. Figure 2 The PET film 10 and the PDMS film 20 are actually two layers of plastic films. The PDMS film 20 is Figure 2 The shaded area of ​​the figure. The sealing methods include chemical bonding, hot pressing, welding, etc. In addition, the sweat collection and detection patch also includes a sensor component 30 formed on the PET film 10 and a serpentine micro-pillar array channel 40 formed on the PDMS film 20, and the sensor component 30 includes a sweat marker detection sensor and a flow rate sensor.

[0032] like Figure 3As shown, a working electrode 2, a reference electrode 3 and a counter electrode 4 are formed on the PET film 10, and these three electrodes together provide an electrochemical sweat marker detection sensor. In addition, a finger electrode 5 is also formed on the PET film 10, which provides a flow rate sensor. These two sensors are connected to the electrochemical workstation through the electrode connection 1 on the PET film 10. In addition, a sample outlet 11 is also formed on the PET film 10. The electrodes 2, 3, 4, 5 here can be prepared by a photolithography gold plating process, for example, by depositing metal on a 100um PET film 10, sputtering 30nmCr / 50nmAu, and patterning the metal electrode by photolithography and lift-off process (usually photolithography before gold plating, lift-off process after gold plating). It should be understood that the electrodes 2, 3, 4, 5 can also be prepared by processes such as screen printing and inkjet printing.

[0033] In particular, the electrodes 2, 3 of the sweat marker detection sensor need to be modified.

[0034] Specifically, Figure 4 As shown, a mixed reagent TTF / CNT 22 of tetrathiafulvalene and carbon nanotubes is drop-cast on a gold electrode 21 as an electron transfer intermediary layer to reduce the voltage value of lactic acid oxidation and reduce interference; a mixed solution 23 of lactate oxidase, carbon nanotubes, and chitosan is drop-cast on the upper layer to catalyze the oxidation of lactic acid and generate electron transfer; in addition, a Nafion reagent 24 is drop-cast on the top layer as a protective layer, thereby obtaining a working electrode 2.

[0035] Specifically, Figure 5 As shown, a uniform Ag / AgCl ink 32 is spin-coated on a gold electrode 31 , and then a PVB / NaCl mixed solution 33 is added dropwise as a protective layer after heating and drying, thereby obtaining a reference electrode 3 .

[0036] like Figure 6 As shown, a sweat inlet 6, a sample inlet chamber 8 and a sample outlet chamber 12 are formed on the PDMS film 20, and three chamber micro-pillars 7 in the two chambers 8 and 12 respectively play a supporting role to ensure that the PET film 10 and the PDMS film 20 are kept apart. Figure 2 The working electrode 2 on the PET film 10 directly corresponds to the sample inlet 6 on the PDMS film 20. The reference electrode 3 and the counter electrode 4 on the PET film 10 are both located in the sample inlet chamber 8 to measure the sweat marker lactic acid here. In addition, a capillary check valve 9 is formed on the PDMS film 20 to prevent sweat from flowing back. The serpentine micro-pillar array channel 40 is arranged between the capillary check valve 9 and the sample outlet chamber 12, providing a capillary micro-flow pump. The surface tension and microstructure increase the capillary force to accelerate the flow of sweat. As a result, the sweat flows forward to the sample outlet chamber 12 in a serpentine flow manner, and flows from the sample outlet 11 (see Figure 3) outflow. Combine Figure 2 The interdigitated electrodes 5 on the PET film 10 directly correspond to the serpentine micro-pillar array channels 40 to measure the flow rate of sweat there.

[0037] like Figure 7 As shown, the length W1 and width W2 of the microcolumn (generally W2 / W1 is less than 1, and W1 is between 100um-1mm), the center Q2 of the microcolumn is aligned with the center Q1 of the microcolumn gap, and the relationship between the lateral spacing S1 and the longitudinal spacing S2 of the microcolumns is closely related to the flow rate of sweat and the time it takes for sweat to fill the channel. When the microcolumn size and the S1 / S2 ratio (usually 1 / 2) are constant, the denser the microcolumns (i.e., the smaller the S1 and S2 sizes), the greater the capillary pressure of the capillary microflow pump, the stronger the ability to drive sweat, the greater the flow rate, and the shorter the time it takes to fill the channel.

[0038] After the sweat enters from the injection port 6, the electrochemical sweat marker detection sensor in contact with the sweat in the injection chamber 8 can detect the lactic acid content, and the IT curve mode on the electrochemical workstation can detect the electrical signal in the lactic acid redox process. The capillary check valve 9 prevents the sweat from flowing back, avoiding the problem of mixing new and old sweat in the injection chamber 8, and then enters the serpentine micro-pillar array channel 40. Under the action of capillary force, the liquid moves along the serpentine manner, and finally the sweat flows out of the patch from the outlet 11. During the flow of sweat in the serpentine micro-pillar array channel 40, the flow rate of the liquid can be controlled by changing the size, number, and gap distance of the serpentine micro-pillar array channel 40.

[0039] For Figure 8 As for the three channels shown in the figure, a is a serpentine non-micropillar array channel, b is a serpentine micropillar array channel 40, and c is a cavity. The simulation results of COMSOL software are shown as follows Fig. 9 As shown, the liquid is driven to flow in under the 70kPa pressure provided by the injection pump. The liquid in the serpentine structure of the micro-pillar array can maintain a relatively stable flow rate in the later stage, while the rate of the non-micro-pillar array serpentine structure will gradually decrease as the flow resistance increases in the later stage. Although the simulation results of the cavity structure show a large liquid rate, it has a large dead volume and large fluctuations, making it difficult to calibrate the flow sensor. Specifically, the serpentine micro-pillar array channel structure is combined with the interdigitated electrode flow sensor to effectively control and measure the sweat flow rate, avoiding the disadvantage of the simple serpentine structure that the flow resistance increases and the flow rate gradually decreases. The serpentine non-micro-pillar structure will gradually increase the flow resistance, causing the flow rate to gradually decrease after the sweat fills the channel, affecting the accuracy of the flow sensor detection. The serpentine micro-pillar array channel can stabilize the flow rate after the sweat fills the entire channel, which is convenient for the accuracy of the flow sensor detection. In fact, when the sweat does not fill the micro-pillar array channel, the flow resistance can be reduced by the capillary pump action, so that it can be filled quickly, which has the effect of accelerating the inflow of sweat, such as Fig. 9 As shown, after the micro-column channel is filled, the micro-column array stabilizes the flow rate at a value, which is convenient for detecting the stable flow rate value. The flow rate size when stable can be controlled by adjusting the gap distance of the micro-column array. Controlling the flow rate size is also a major advantage of the serpentine micro-column array channel 40.

[0040] according to Fig.10 The experimental results show that the injection pump is set to a small pressure drive of 0.7 kPa. As the liquid advances in the serpentine micro-pillar array channel, the forward flow rate of the liquid gradually increases, while the serpentine non-micro-pillar array structure shows a gradually decreasing trend, which illustrates the effect of the capillary micro-flow pump in driving the flow of liquid. Specifically, the time for sweat to fill up through the serpentine micro-pillar array channel 40 is shorter than that of the serpentine non-micro-pillar array channel, and the flow rate gradually increases, accelerating the sweat to flow into the detection chamber. In addition, the capillary pressure can be controlled by adjusting the longitudinal and transverse micro-pillar spacing to affect the flow rate of sweat in the channel, which confirms that the capillary micro-flow pump increases the effect of actively driving sweat.

[0041] like Fig.11 As shown, the admittance values ​​(frequency is 1 kHz) of artificial sweat corresponding to different flow rates are measured by the EIS (electrical impedance spectroscopy scanning) mode of the electrochemical workstation. As the flow rate increases from 0 to 60 μl / min, the admittance of the flow rate sensor also increases, verifying that the function of the sweat patch to detect flow rate is feasible, thereby realizing the functional verification and characterization of the flow rate sensor of the interdigitated electrode 5.

[0042] The test results of the sweat marker detection sensor modified by TTF / CNT as an intermediary layer are as follows Fig.12 As shown, in the range of 0 to 22 mM, the concentration increased by 2 mM, and the measured sensitivity was 7.36 μA / mM·cm 2 (R 2 =0.996), verifying that the proposed sweat patch lactate detection function is feasible, thereby achieving functional verification and characterization of the lactate electrochemical sensor.

[0043] In summary, the present invention can effectively collect sweat from the body surface, avoid evaporation and contamination, and perform real-time quantitative detection of multiple parameters through the integration of microfluidic technology and electrochemical sensors; by designing a serpentine microcolumn array channel structure capillary microfluidic pump combined with an interdigitated electrode structure, self-driving of sweat and flow rate detection can be achieved, while accurate detection of sweat metabolites at the entrance can be achieved.

[0044] In the present invention, sweat flows into the inlet of the patch by capillary force, which is a spontaneous inflow without human intervention. The capillary microflow pump structure (snake-shaped micro-column array channel) is placed at the back, which can drive the sweat to circulate faster in the micro-chamber and channel. This capillary microflow pump effect is caused by surface tension and the design of the microstructure itself.

[0045] The inlet and outlet of the present invention can also be equipped with hydrogel and hydrophilic polymer materials to increase the efficiency of absorbing sweat.

[0046] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A sweat collection and detection patch based on a capillary microflow pump, characterized in that: The sweat collection and detection patch includes a PET film, a PDMS film, a sensor assembly and a serpentine micro-column array channel, wherein the periphery of the PET film and the PDMS film are sealed and connected, the sensor assembly includes a sweat marker detection sensor and a flow rate sensor, the PET film is formed with a sweat marker detection sensor provided by a working electrode, a reference electrode and a counter electrode, the PET film is also formed with a flow rate sensor provided by an interdigitated electrode, the PDMS film is formed with a sampling chamber, the sweat marker detection sensor is directly opposite to the sampling chamber with a counter electrode The markers of sweat are measured, a serpentine micro-column array channel is formed on the PDMS film, a flow rate sensor is facing the serpentine micro-column array channel to measure the flow rate of sweat, a sweat inlet is formed on the PDMS film, a working electrode is directly arranged corresponding to the inlet, a sweat outlet is formed on the PET film, and it is arranged opposite to the liquid outlet chamber on the PDMS film, the inlet and / or the outlet have hydrogel and hydrophilic polymer materials to increase the efficiency of absorbing sweat, and a plurality of chamber micro-columns for supporting are arranged in the inlet chamber and / or the liquid outlet chamber.

2. The sweat collection and detection patch according to claim 1, characterized in that: A capillary check valve is formed on the PDMS film, which is located between the injection chamber and the serpentine micropillar array channel to prevent sweat from flowing back.

3. The sweat collection and detection patch according to claim 1, characterized in that: The micropillars in the channels of the serpentine micropillar array have the same or different lengths and widths.

4. The sweat collection and detection patch according to claim 1, characterized in that: The distances between adjacent micropillars in the channels of the serpentine micropillar array are the same or different.

5. The sweat collection and detection patch according to claim 1, characterized in that: The working electrode was modified by TTF / CNT as an intermediary layer.

6. The sweat collection and detection patch according to claim 1, characterized in that: The sweat marker detection sensor and the flow rate sensor are connected to the electrochemical workstation through the electrode connections on the PET film.

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