Paper-based microfluidic cavity structure and method for in-situ sweat collection and detection

Abstract

The invention discloses a paper-based microfluidic cavity structure and method for in-situ sweat collection and detection, and belongs to the field of wearable body surface sweat monitoring equipment. According to the paper-based microfluidic cavity structure, the sweat reaction area and the flexible hydrophilic substrate layer are connected through the double faced adhesive tape, a hollow cavity micro space for sweat storage and detection is formed, and sufficient sweat can be enriched for accurate detection of a paper-based electrochemical sensor. One-step preparation of the paper-based electrochemical sensor is realized by using the mixed conductive ink prepared from PEDOT: PSS / D-sorbitol / MWCNTS / PB NPs, so that the preparation steps of the sensor are greatly simplified, and the stability and biocompatibility of the sensor are improved. The wearable device can be worn on each part of a human body and is used for local sweat collection and accurate detection in the autonomous sweating process of the human body or after iontophoresis.

Description

Technical Field

[0001] This invention belongs to the field of wearable sweat monitoring devices, specifically relating to a paper-based microfluidic cavity structure and method for in-situ sweat collection and detection. Background Technology

[0002] Sweat, as a representative bodily fluid, contains abundant biomarkers related to health status, and has great potential for non-invasive and continuous monitoring of biomarkers. In particular, analyzing exercise-related health or disease-related biomarkers using multi-parameter detection systems can yield richer molecular information for exercise health management and disease diagnosis and management.

[0003] In recent years, thanks to advancements in wearable technology, wearable electrochemical sensors have provided a more reliable and convenient platform for sweat detection. Effective sweat collection from the skin surface and prevention of mixing of new and old sweat in wearable devices are crucial for reliable downstream sensing. Therefore, microfluidic systems based on various materials such as PDMS, adhesives, polymer films, and paper have been developed to address these issues. Among them, paper-based microfluidics, due to their porous fiber networks and hydrophilicity, exhibit excellent breathability and sweat transport capabilities, making them an attractive option. Furthermore, the low cost, porous structure, and ease of handling of paper also make it an ideal substrate material for wearable electrochemical sensors. Therefore, paper can serve as a universal substrate for microfluidic channels and sensors, solving the material compatibility problem for different functional modules in wearable devices. However, existing paper-based electrochemical sensors mainly employ surface modification techniques, such as screen printing or inkjet printing, which do not fully utilize the three-dimensional porous structure of paper, resulting in limited electroactive area and sensitivity. Moreover, the utilization of the three-dimensional porous structure of paper requires sufficient wetting of the electrodes in sweat to ensure the accuracy and consistency of in vitro and in vivo testing.

[0004] Therefore, developing a paper-based microfluidic cavity structure and method for in-situ sweat collection and detection is of great importance for sports health monitoring and disease management. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the prior art and to provide a paper-based microfluidic cavity structure and method for in-situ sweat collection and detection.

[0006] The specific technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a paper-based microfluidic cavity structure for in-situ sweat collection and detection, including a paper-based microfluidic cavity structure and a flexible circuit board; The paper-based microfluidic cavity structure comprises, from bottom to top, a PU layer, a paper-based microfluidic layer, double-sided adhesive, and a flexible hydrophilic substrate layer stacked vertically. The paper-based microfluidic layer includes a connected sweat collection area and a sweat reaction area. The PU layer covers the bottom area of ​​the paper-based microfluidic layer except for the sweat collection area. A portion of the double-sided adhesive above the sweat reaction area is perforated to provide cavity space for sweat storage and detection. The reaction area of ​​the flexible hydrophilic substrate layer is located above the perforated portion of the double-sided adhesive. The flexible hydrophilic substrate includes a paper-based electrochemical sensor array disposed on the upper surface of the flexible hydrophilic substrate; the paper-based electrochemical sensor array includes a reference electrode, a counter electrode, and... n One working electrode for measuring different metabolites. n ≥1; Each electrode is led out through a wire to a circuit interface set on a flexible hydrophilic substrate and connected to a flexible circuit board.

[0007] Preferably, the paper-based microfluidic layer is made of filter paper, the sweat collection area is used to directly contact the skin and collect sweat through capillary action, and the sweat reaction area is used to guide the sweat collected in the sweat collection area to the cavity space.

[0008] Preferably, the double-sided adhesive is a medical double-sided adhesive, with the periphery of the hollowed-out area larger than the sweat reaction area, used to connect the skin, the paper-based microfluidic layer, and the flexible hydrophilic base layer.

[0009] Preferably, the working electrode is prepared by dripping conductive ink onto a blank paper substrate and then modifying it with an electrochemically sensitive layer. The conductive ink comprises 1.0%-2.5% by mass of the conductive polymer PEDOT:PSS, 45-180 mg / mL of biocompatible D-sorbitol, 1-5 mg / mL of carboxylated multi-walled carbon nanotubes, and 10-50 mg / mL of a catalytic material, wherein the catalytic material is at least one of Prussian blue nanoparticles and Pt nanoparticles. The electrochemically sensitive layer is an ion-selective membrane layer for detecting corresponding ions or an enzyme layer for detecting related metabolites through an enzyme reaction.

[0010] Preferably, a sweat outlet is provided on the flexible hydrophilic substrate near the edge of the double-sided adhesive cutout area.

[0011] Preferably, the paper-based electrochemical sensor array is connected to pads located on the upper surface of a flexible hydrophilic substrate via a conductive paste.

[0012] Preferably, the flexible hydrophilic substrate is at least one of PI and PET, and the hydrophilicity is achieved by at least one of plasma treatment, ultraviolet treatment, and surfactant treatment.

[0013] Preferably, the flexible circuit board includes an electrochemical multiplexing module and a wireless communication module; the electrochemical multiplexing module is used to control the voltage applied to the paper-based electrochemical sensor array to perform simultaneous electrochemical detection of multiple metabolic markers in sweat; the wireless communication module is used to send the detection results to an external receiver.

[0014] Furthermore, the external receiving end is a mobile device with real-time display capabilities.

[0015] Secondly, the present invention provides a method for in-situ sweat collection and detection using the paper-based microfluidic cavity structure described in any one of the first aspects, as follows: The sweat collection area is fixed to the skin and brought into direct contact using double-sided adhesive. The sweat collection area collects sweat through capillary action and then guides the collected sweat to the sweat reaction area. The sweat passes through the cavity space of the double-sided adhesive cutout area and enters the detection area of ​​the flexible hydrophilic substrate. Metabolic markers in the sweat are simultaneously electrochemically detected in the detection area using a three-electrode system of a paper-based electrochemical sensor array. The detection results are then sent to an external receiver via a flexible circuit board.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The paper-based microfluidic cavity structure of the present invention provides sufficient sweat volume for the sweat detection of paper-based sensors, making in-situ sweat detection more accurate.

[0017] (2) The present invention uses conductive polymer ink to prepare conductive paper-based devices. The preparation method is simple and fast, and high-performance conductive paper can be obtained without complicated processing conditions and post-processing.

[0018] (3) The present invention utilizes an electrochemical sensor array to achieve simultaneous monitoring of multiple biomarkers, and all test data are transmitted and displayed on an external receiving end (e.g., a mobile APP) via a flexible circuit board (e.g., loaded with a Bluetooth module), which is more reliable than the detection of a single biomarker. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the vertical layering of the paper-based microfluidic cavity structure used for in-situ sweat collection and detection in this embodiment; Figure 2 A schematic diagram of the stacked paper-based microfluidic cavity structure used for in-situ sweat collection and detection; The attached figures are labeled as follows: paper-based microfluidic cavity structure 1-4, PU layer 1, paper-based microfluidic layer 2, double-sided adhesive 3, flexible hydrophilic substrate layer 4, flexible circuit board 5, sweat collection area 201, sweat reaction area 202, paper-based electrochemical sensor array 401, flexible hydrophilic substrate 402, working electrode 401-3, reference electrode 401-2, counter electrode 401-1, electrochemical sensitive layer 401-4, sweat outlet 402-1, solder pad 402-2, and circuit interface 402-3. Detailed Implementation

[0020] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0021] like Figure 2 As shown, this invention provides a paper-based microfluidic cavity structure for in-situ sweat collection and detection. The device mainly includes paper-based microfluidic cavity structures 1-4 and a flexible circuit board 5.

[0022] In the device of the present invention, such as Figure 1 As shown, the paper-based microfluidic cavity structure 1-4 consists of four layers, each tightly stacked vertically. The first layer is a PU layer 1, the second is a paper-based microfluidic layer 2, the third is double-sided adhesive 3, and the fourth is a flexible hydrophilic base layer 4. These four layers together form a single unit. The paper-based microfluidic layer 2 includes a connected sweat collection area 201 and a sweat reaction area 202, connected by a narrow section of filter paper. The PU layer 1 is at the bottom, covering the bottom of the paper-based microfluidic layer 2 except for the sweat collection area 201. It seals the sweat reaction area 202 and the bottom of the connecting section between the two areas, preventing direct contact between the reaction area and the skin. The double-sided adhesive 3 is partially perforated above the sweat reaction area 202, providing cavity space for sweat storage and detection. The reaction area of ​​the flexible hydrophilic base layer 4 is located above the perforated portion of the double-sided adhesive 3.

[0023] In a preferred embodiment of the present invention, the paper-based microfluidic layer 2 is made of ordinary filter paper and mainly consists of two parts: a sweat collection area 201 and a sweat reaction area 202. The sweat collection area 201 is for direct contact with the skin and can quickly and efficiently collect sweat through capillary action. The sweat reaction area 202 is used to guide the sweat collected in the sweat collection area 201 into the hollow cavity structure of the double-sided adhesive 3 for sweat storage and detection.

[0024] In a preferred embodiment of the present invention, the double-sided adhesive 3 is a medical-grade double-sided adhesive. The periphery of the hollowed-out area should be larger than the sweat reaction area 202, for simultaneously connecting the skin, the paper-based microfluidic layer 2, and the flexible hydrophilic substrate layer 4. The hollowed-out area provides a channel for sweat to flow from the reaction area 202 of the paper-based microfluidic layer 2 to the reaction area of ​​the paper-based electrode array 401 of the flexible hydrophilic substrate, allowing the paper-based electrochemical sensing array on the flexible hydrophilic substrate to be fully immersed in sweat for accurate detection of sweat components. At the same time, the non-hollowed-out area should be large enough to connect the second and fourth layers and to be directly fixed to the skin surface.

[0025] In the device of the present invention, such as Figure 1 As shown, the flexible hydrophilic substrate layer 4 mainly includes a flexible hydrophilic substrate 402 and a paper-based electrochemical sensor array 401, wherein the paper-based electrochemical sensor array 401 is disposed on the upper surface of the flexible hydrophilic substrate 402. The paper-based electrochemical sensor array 401 mainly includes a reference electrode 401-2, a counter electrode 401-1, and... n One working electrode 401-3 for measuring different metabolites. n ≥1. Each electrode is led out of the circuit interface 402-3 through a wire and then connected to the flexible circuit board 5. The circuit interface 402-3 is disposed on the flexible hydrophilic substrate 402.

[0026] In a preferred embodiment of the present invention, the working electrode 401-3 is prepared by dripping conductive ink onto a blank paper substrate (the added conductive ink needs to wet the working electrode). Depending on the function of the working electrode, a secondary electrochemical sensitive layer 401-4 needs to be modified on the working electrode. For example, in actual use, after dripping conductive ink onto the working electrode, it is treated at 130°C for 2 hours, then sealed with wax for insulation, and then the electrochemical sensitive layer is modified again according to the function of the working electrode.

[0027] As a preferred embodiment of the present invention, the conductive ink comprises 1.0%-2.5% by mass of conductive polymer PEDOT:PSS, 45-180 mg / mL of biocompatible D-sorbitol, 1-5 mg / mL of carboxylated multi-walled carbon nanotubes, and 10-50 mg / mL of catalytic material, wherein the catalytic material is at least one of Prussian blue nanoparticles and Pt nanoparticles.

[0028] For example, in practical applications, conductive ink can be composed of a conductive polymer PEDOT:PSS, biocompatible D-sorbitol, carboxylated multi-walled carbon nanotubes, and Prussian blue nanoparticles. The concentrations of the four substances are 2 mg / mL, 180 mg / mL, 2 mg / mL, and 50 mg / mL, respectively. Indirect detection of biomarkers is achieved through the low-potential detection of hydrogen peroxide by Prussian blue at -0.1V.

[0029] As a preferred embodiment of the present invention, the electrochemical sensitive layer 401-4 may be an ion-selective membrane layer for detecting ions, or an enzyme layer for detecting related metabolites by enzyme reaction.

[0030] For example, when n When =3, that is, when three working electrodes are used, the electrochemical sensitive layers that are modified on the surface of the three working electrodes can be, respectively, a potassium ion selective membrane layer for detecting potassium ions, a glucose oxidase for detecting glucose, and a mixed enzyme of creatinine enzyme, creatine enzyme, and sarcosine oxidase for detecting creatinine.

[0031] In practical applications, the conductivity of the conductive ink is achieved by adjusting the mass fractions of PEDOT:PSS, D-sorbitol, and carboxylated multi-walled carbon nanotubes, while the detection performance is achieved by adjusting the concentration of the catalytic material.

[0032] In a preferred embodiment of the present invention, a single, independent working electrode, a reference electrode, and a counter electrode are fabricated using screen printing and laser cutting techniques. The working electrode area lacks a screen-printed layer and consists of untreated blank filter paper. The final working electrode is then obtained by adding conductive ink and performing secondary modification of the electrochemical sensitive layer. For example, in practical applications, a silver / silver chloride layer and a carbon paste layer can be sequentially deposited on the filter paper using screen printing to fabricate a reference electrode, a carbon electrode (i.e., a counter electrode), and a working electrode in a blank working area. These are then fabricated as single, independent working electrodes, a reference electrode, and a counter electrode using laser cutting techniques.

[0033] In a preferred embodiment of the present invention, a sweat outlet 402-1 is provided on the flexible hydrophilic substrate 402 near the edge of the hollow area of ​​the double-sided adhesive 3, and the sweat outlet 402-1 is used to realize dynamic monitoring of sweat.

[0034] In a preferred embodiment of the present invention, the paper-based electrochemical sensor array 401 is connected to pads 402-2 on the upper surface of a flexible hydrophilic substrate 402 via a conductive paste. The pads 402-2 are connected to a circuit interface 402-3 via wires. For example, in practical use, silver paste can be used as the conductive paste. The paper-based electrochemical sensor array 401 is connected to the pads 402-2 via the silver paste. After drying, it is covered with a PU film to prevent silver paste leakage.

[0035] As a preferred embodiment of the present invention, the flexible hydrophilic substrate 402 is at least one of PI and PET, and the hydrophilicity is achieved by at least one of plasma treatment, ultraviolet treatment and surfactant treatment. The hydrophilic treatment makes it easier for sweat to fill the cavity structure.

[0036] In a preferred embodiment of the present invention, the flexible circuit board 5 includes an electrochemical multiplexing detection module and a wireless communication module. The electrochemical multiplexing detection module controls the voltage applied to the three-electrode system in the paper-based electrochemical sensor array 401 to perform simultaneous electrochemical detection of multiple metabolic markers in sweat. For example, in practical use, the target analyte can be detected by applying a detection potential of -0.1 V to the two enzyme-based working electrodes, while ion detection is performed by measuring the potential difference between the reference electrode and the working electrode. The wireless communication module reads the detection results and sends them to an external receiver, which can be a mobile device with real-time display capabilities. For example, in practical use, Bluetooth can be used for wireless transmission, with a mobile phone serving as the receiver capable of displaying the measurement results in real time.

[0037] Furthermore, during use, the device of this invention can be tightly attached to the subject's skin surface using auxiliary fixing components such as a 3D-printed shell and a PU film. Sweat is collected in the sweat collection area and transported to the reaction area. After a period of collection, when the sweat fills the paper-based microfluidic cavity structure, electrochemical detection is performed, and the sweat is ultimately discharged through the sweat outlet on the flexible hydrophilic substrate. The measurement results of the electrochemical sensor array can be displayed in real time via a mobile app.

[0038] Based on the above-mentioned paper-based microfluidic cavity structure, the present invention also provides an in-situ sweat collection and detection method, which is as follows: The sweat collection area 201 is fixed to the skin and made into direct contact by the adhesive of the double-sided tape 3. The sweat collection area 201 collects sweat through capillary action. The sweat collected by the sweat collection area 201 is then guided to the sweat reaction area 202. The sweat passes through the cavity space of the hollow area of ​​the double-sided tape 3 and enters the detection area of ​​the flexible hydrophilic base layer 4. Metabolic markers in the sweat are simultaneously electrochemically detected in the detection area by the three-electrode system of the paper-based electrochemical sensor array 401. The detection results are then sent to the external receiving end through the flexible circuit board 5.

[0039] This example uses the detection of glucose, creatinine, and potassium ions. Glucose and creatinine detection are achieved through enzymatic reactions; the specific reaction principle is as follows: Glucose + O2 + H2O → Gluconic acid + H2O2 (glucose oxidase); Creatinine + H2O → creatine (creatinine enzyme); Creatine + H2O → sarcosine + urea (creatine enzyme); Sarcosine + O2 + H2O → Glycine + Formaldehyde + H2O2 (sarcosine oxidase); Glucose is converted to hydrogen peroxide via the catalytic action of glucose oxidase; creatinine is converted to hydrogen peroxide via a cascade reaction of three enzymes (creatinine oxidase, creatine oxidase, and sarcosine oxidase); dynamic monitoring of glucose and creatinine in sweat is achieved by utilizing the current response of Prussian blue nanoparticles to hydrogen peroxide at -0.1V. The preparation method of the working electrode for glucose and creatinine detection is as follows: Glucose electrode preparation: First, prepare a mixed solution of 60 mg / mL glucose oxidase and 20 mg / mL bovine serum albumin. Then, add glutaraldehyde to prepare a mixed solution containing 0.25 wt% glutaraldehyde. Add 2.5 μL of this solution to the surface of the working electrode and dry it overnight at 4°C. The electrode is then ready for glucose detection.

[0040] Creatinine electrode preparation: First, mix 30 U / uL of creatinine enzyme, 3 U / uL of creatine enzyme and 2.5 U / uL of creatine oxidase in equal volume ratio, then add glutaraldehyde to prepare a three-enzyme mixed solution containing 0.25 wt% glutaraldehyde. Add 2.5 uL of this solution to the surface of the working electrode, dry it overnight at 4°C, and it can be used to detect creatinine.

[0041] Potassium ion detection is achieved through the specific recognition of potassium ion-selective membranes. The preparation method of potassium ion-selective membranes is as follows: Dissolve 2 mg valamicin, 0.5 mg sodium tetraphenylborate, 30 mg PVC, 25 mg SEBS and 70 mg DOS in 660 μL of cyclohexanone solution.

[0042] Add 2.5 μL of the above solution to the surface of the working electrode, let it air dry at room temperature, and then it can be used for detection.

[0043] The paper-based microfluidic cavity structure of this invention connects the sweat reaction region and the flexible hydrophilic substrate layer with double-sided adhesive, forming a perforated microspace for sweat storage and detection. This allows for the accumulation of sufficient sweat for accurate detection by the paper-based electrochemical sensor. This invention utilizes a hybrid conductive ink prepared from PEDOT:PSS / D-sorbitol / MWCNTS / PB NPs to achieve a one-step fabrication of the paper-based electrochemical sensor, significantly simplifying the sensor fabrication process and improving its stability and biocompatibility. This wearable device can be worn on various parts of the body for localized sweat collection and accurate detection during spontaneous sweating or after iontophoresis.

[0044] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A paper-based microfluidic cavity structure for in-situ sweat collection and detection, characterized in that, Including paper-based microfluidic cavity structures (1-4) and flexible circuit boards (5); The paper-based microfluidic cavity structure (1-4) includes a PU layer (1), a paper-based microfluidic layer (2), double-sided adhesive (3), and a flexible hydrophilic base layer (4) stacked vertically from bottom to top. The paper-based microfluidic layer (2) includes a connected sweat collection area (201) and a sweat reaction area (202). The PU layer (1) covers the bottom area of ​​the paper-based microfluidic layer (2) except for the sweat collection area (201). The double-sided adhesive (3) above the sweat reaction area (202) is hollowed out to provide cavity space for sweat storage and detection. The reaction area of ​​the flexible hydrophilic base layer (4) is located above the hollowed-out part of the double-sided adhesive (3). The flexible hydrophilic substrate layer (4) includes a paper-based electrochemical sensor array (401) disposed on the upper surface of the flexible hydrophilic substrate (402); the paper-based electrochemical sensor array (401) includes a reference electrode (401-2), a counter electrode (401-1), and n One working electrode (401-3) for measuring different metabolites. n ≥1; Each electrode is led out through a wire to a circuit interface (402-3) set on a flexible hydrophilic substrate (402) and connected to a flexible circuit board (5).

2. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The paper-based microfluidic layer (2) is made of filter paper. The sweat collection area (201) is used to directly contact the skin and collect sweat through capillary action. The sweat reaction area (202) is used to guide the sweat collected in the sweat collection area (201) to the cavity space.

3. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The double-sided tape (3) is a medical double-sided tape with the outer periphery of the hollow area larger than the sweat reaction area (202), used to connect the skin, the paper-based microfluidic layer (2) and the flexible hydrophilic base layer (4).

4. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The working electrode (401-3) is prepared by dripping conductive ink onto a blank paper substrate and then modified with an electrochemically sensitive layer (401-4). The conductive ink comprises 1.0%-2.5% by mass of conductive polymer PEDOT:PSS, 45-180 mg / mL of biocompatible D-sorbitol, 1-5 mg / mL of carboxylated multi-walled carbon nanotubes, and 10-50 mg / mL of catalytic material, wherein the catalytic material is at least one of Prussian blue nanoparticles and Pt nanoparticles. The electrochemically sensitive layer (401-4) is an ion-selective membrane layer for detecting ions or an enzyme layer for detecting related metabolites through enzyme reactions.

5. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, A sweat outlet (402-1) is provided on the flexible hydrophilic substrate (402) near the edge of the hollow area of ​​the double-sided adhesive (3).

6. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The paper-based electrochemical sensor array (401) is connected to pads (402-2) on the upper surface of a flexible hydrophilic substrate (402) via a conductive paste.

7. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The flexible hydrophilic substrate (402) is at least one of PI and PET, and its hydrophilicity is achieved by at least one of plasma treatment, ultraviolet treatment, and surfactant treatment.

8. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 1, characterized in that, The flexible circuit board (5) includes an electrochemical multiplex detection module and a wireless communication module; the electrochemical multiplex detection module is used to control the voltage applied in the paper-based electrochemical sensor array (401) to perform simultaneous electrochemical detection of multiple metabolic markers in sweat; the wireless communication module is used to send the detection results to an external receiver.

9. The paper-based microfluidic cavity structure for in-situ sweat collection and detection according to claim 8, characterized in that, The external receiver is a mobile device with real-time display capabilities.

10. A method for in-situ sweat collection and detection using the paper-based microfluidic cavity structure according to any one of claims 1 to 9, characterized in that, Specifically as follows: The sweat collection area (201) is fixed to the skin and made into direct contact by the adhesive of double-sided tape (3). The sweat collection area (201) collects sweat through capillary action. Then, the sweat collected by the sweat collection area (201) is guided to the sweat reaction area (202). The sweat passes through the cavity space of the hollow area of ​​the double-sided tape (3) and enters the detection area of ​​the flexible hydrophilic base layer (4). The metabolic markers in the sweat are synchronously electrochemically detected in the detection area by the three-electrode system of the paper-based electrochemical sensor array (401). Then, the detection results are sent to the external receiving end through the flexible circuit board (5).

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