Three-dimensional paper-based microfluidic electrochemical analysis device for sweat in-situ monitoring

Abstract

The invention relates to the field of physiological status detection, and provides a three-dimensional paper-based microfluidic electrochemical analysis device for sweat in-situ monitoring. The device is characterized in that the three-dimensional paper-based microfluidic network and the electrochemical sensing array are integrated, so that various substances in human sweat can be monitored at the same time, and real-time and accurate physiological state information can be provided. The core of the invention lies in that a layer-by-layer manufacturing method is adopted to realize direct preparation of the three-dimensional paper-based microfluidic network, and the three-dimensional paper-based microfluidic network has high customizability. The polydimethylsiloxane is used as a key material, not only serves as a hydrophobic barrier of the microchannel to effectively prevent fluid leakage, but also serves as an adhesive to enhance the overall structural stability of the device. In addition, the flexible electrochemical sensing array is embedded into the three-dimensional paper-based microfluidic network, so that synchronous monitoring of various substances in sweat is realized. The invention provides a new method for manufacturing the three-dimensional paper-based microfluidic analysis device, and has a wide application prospect in the fields of personalized diagnosis and physiological monitoring.

Description

Technical Field

[0001] The present invention belongs to the field of physiological state detection, and particularly relates to a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat. Background Art

[0002] Paper-based microfluidic devices are widely used in fields such as food detection, bioanalysis, and environmental monitoring due to their advantages of simple operation, low cost, portability, and user-friendliness. Such devices can be combined with various analytical methods such as electrochemistry and colorimetry, and can be used as point-of-care testing devices for in-vitro diagnosis and wearable devices for in-situ analysis. Such devices usually consist of two parts: a microfluidic network and a sensing unit. The former is responsible for sample collection, and the latter is used for sample detection and analysis.

[0003] Paper-based microfluidic devices mainly include single-layer and multi-layer (three-dimensional) configurations. The geometric design of single-layer devices is simple, easy to integrate with analytical methods, and has excellent performance in stable sample control and analysis on a two-dimensional plane. However, limited by space, such devices cannot meet the detection requirements for complex samples or higher precision. In contrast, three-dimensional structures can better meet the needs of manipulating and analyzing complex fluids. Through various fluid manipulation modes, it can be customized according to different reaction and detection requirements. Currently, multi-layer structures are mainly prepared by stacking and origami. Stacked microfluidic devices are formed by stacking multiple functionalized papers, while origami microfluidic devices are realized by folding a paper with different functional regions. Although both methods can achieve the construction of multi-layer structures, additional components are required to establish connections between layers. This method increases the complexity and cost of the manufacturing process, and cannot ensure stable and precise connections between each layer of functional regions, thus limiting the accuracy and repeatability of detection. Summary of the Invention

[0004] The object of the present invention is to overcome the above-mentioned deficiencies in the prior art and provide a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat.

[0005] The first object of the present invention is to provide a three-dimensional paper-based microfluidic electrochemical analysis device.

[0006] The second object of the present invention is to provide the use of the three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat.

[0007] The third object of the present invention is to provide a device for real-time and in-situ detection of components in sweat.

[0008] To achieve the above object, the present invention is realized through the following solutions:

[0009] A three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring, comprising a three-dimensional paper-based microfluidic network layer for sweat transmission and a flexible electrochemical sensing array layer for sweat analysis;

[0010] The three-dimensional paper-based microfluidic network layer includes two layers of filter paper, one layer of insulating layer, and two layers of patterned polydimethylsiloxane layers;

[0011] The insulating layer is located above the lower filter paper, and the insulating layer includes an inlet;

[0012] The patterned polydimethylsiloxane layer includes upper and lower layers. The lower polydimethylsiloxane layer is located between the insulating layer and the upper filter paper. The lower polydimethylsiloxane layer includes an inlet, three channels, and three analysis areas. The upper polydimethylsiloxane layer is located on the upper filter paper, and the upper polydimethylsiloxane layer includes an inlet, three channels, and three analysis areas;

[0013] The inlet of the lower polydimethylsiloxane layer is aligned with the inlet of the insulating layer, and the inlet, three channels, and three analysis areas of the upper polydimethylsiloxane layer are respectively aligned with the inlet, three channels, and three analysis areas of the lower polydimethylsiloxane layer;

[0014] The electrochemical sensing array layer includes a pair of two-electrode systems and two pairs of three-electrode systems. The electrochemical sensing array is located above the insulating layer, and the sensing part of the electrochemical sensing array corresponds to the three analysis areas of the lower polydimethylsiloxane layer.

[0015] Preferably, the polydimethylsiloxane material is prepared from a precursor liquid and a curing liquid.

[0016] More preferably, the preparation method of the patterned polydimethylsiloxane layer is the inkjet printing technique. Using the precursor liquid and the curing liquid as ink, and the nanofiber membrane as the substrate, heating is used to cure the PDMS to obtain it.

[0017] More preferably, before curing, the polydimethylsiloxane is pretreated by storing it at 4 °C for 36 hours.

[0018] Preferably, the moving speed and nozzle diameter of the inkjet printing technique for preparing the patterned polydimethylsiloxane substrate are 0.5 mm / s and 210 μm, respectively.

[0019] Preferably, the number of the electrochemical detection units is at least 1.

[0020] More preferably, the number of the electrochemical detection units is 3, which are respectively used to detect chloride ions, glucose, and lactic acid in the sweat sample.

[0021] More preferably, sensing materials for detecting chloride ions, glucose, and lactic acid are modified on the corresponding working electrodes of the electrochemical sensing array, and the array is dried in an environment at 4 °C.

[0022] Preferably, a layer of gold particles, Prussian blue nanoparticles, and an analytical reagent are deposited on the working electrodes of the electrochemical sensing array.

[0023] Preferably, the reference electrode material of the electrochemical sensing array is silver / silver chloride, and the working electrode material is carbon paste.

[0024] During use, the sensor is attached to the skin surface. The sweat on the skin reaches the analysis area through the inlet and contacts the sensing units in the analysis area. The target substances in the sweat interact with the sensing units of the paper-based analytical device to generate electrical signals, and the signals are wirelessly transmitted to the user through the integrated circuit board, realizing in-situ sweat analysis.

[0025] Compared with the prior art, the present invention has the following characteristics:

[0026] The present invention discloses a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring. The device has remarkable innovation and practicality. By ingeniously integrating a three-dimensional paper microfluidic network with an electrochemical sensing array, a new analysis system is constructed. This design not only allows for in-situ monitoring of chloride ions, glucose, and lactic acid in sweat but also improves the accuracy and repeatability of detection. In the construction process, polydimethylsiloxane is selected as the hydrophobic barrier and adhesive to construct a three-dimensional paper microfluidic network, ensuring excellent sealing and fluid control of the device. The integration of the electrochemical sensing array further transforms the three-dimensional microfluidic network into a three-dimensional paper-based microfluidic electrochemical analysis device with powerful detection functions. This design significantly reduces the dependence on additional components and simplifies the manufacturing process. In addition, the device is combined with a wearable device. The circuit board performs signal processing and transmission functions, and the data can be transmitted to the user interface via Bluetooth, making real-time monitoring and data analysis simple and feasible. This manufacturing strategy of the integrated three-dimensional paper-based microfluidic analysis device provides strong technical support for disease diagnosis and personalized healthcare. Description of the Drawings

[0027] Figure 1 Schematic diagram of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring;

[0028] Figure 2 Physical diagram of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring;

[0029] Figure 3 Anti-interference property of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring.

[0030] Figure 4 The anti-mechanical deformation performance of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring.

[0031] Figure 5 The stability of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring.

[0032] Figure 6 The real-time concentration curve of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring when used for in-situ sweat monitoring.

[0033] Figure caption: 1 - Three-dimensional paper-based microfluidic network layer; 11 - Lower filter paper; 12 - Insulating layer; 13 - Lower patterned polydimethylsiloxane layer; 14 - Upper filter paper; 15 - Upper patterned polydimethylsiloxane layer; 2 - Electrochemical sensing array layer. Detailed implementation manners

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, these embodiments are only used to explain the present invention and are not limited to the following embodiments. The materials used in the following embodiments are obtained from commercial sources unless otherwise specified.

[0035] Embodiment 1 A three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring

[0036] As Figure 1 shown, a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring includes a stacked three-dimensional paper-based microfluidic layer 1 and an electrochemical sensing array layer 2.

[0037] The three-dimensional paper-based microfluidic layer 1 includes a lower filter paper 11, an insulating layer 12, a lower patterned polydimethylsiloxane layer 13, an upper filter paper 14, and an upper patterned polydimethylsiloxane layer 15 stacked in sequence.

[0038] The inlet of the lower patterned polydimethylsiloxane layer 13 corresponds to the inlet of the insulating layer 12.

[0039] The inlet, channels, and analysis areas of the upper patterned polydimethylsiloxane layer 15 correspond to the inlet, channels, and analysis areas of the lower patterned polydimethylsiloxane layer 13, respectively.

[0040] The electrochemical sensing array layer 2 includes three sensing units for glucose, lactate, and chloride ion analysis respectively; the three sensing units of the electrochemical sensing array layer 2 correspond to the three analysis areas of the lower patterned polydimethylsiloxane layer 13 respectively.

[0041] The lower patterned polydimethylsiloxane layer 13 serves as an adhesive and a hydrophobic layer to bond the two layers of filter paper together, thus enabling the integrated fabrication of a three-dimensional microfluidic network.

[0042] The device is in contact with the skin. Sweat enters the device through the insulating layer inlet, flows into the inlet of the patterned microfluidic network, and then enters the three analysis regions through three branch channels, contacting the sensing units in the analysis regions to generate electrochemical signals.

[0043] As Figure 2 shown, it is a physical diagram of the device.

[0044] Example 2 Preparation method of a three-dimensional paper-based microfluidic electrochemical analysis device for in-situ sweat monitoring

[0045] 1. Device preparation

[0046] A layer of insulating ink is screen-printed on the lower filter paper to create an insulating paper layer with an inlet. The use of insulating ink can prevent the non-functional areas of the electrochemical sensing array from contacting sweat, thus avoiding signal interference. An electrochemical sensing array containing two three-electrode systems and one two-electrode system is screen-printed on the insulating paper layer to analyze glucose, lactate, and chloride ions in sweat;

[0047] The lower polydimethylsiloxane is printed on the insulating layer using direct writing technology to form a microfluidic wall; then the upper filter paper is placed, and the upper patterned polydimethylsiloxane is printed on the filter paper (heating temperature 70 °C). The lower polydimethylsiloxane serves as an adhesive to bond the two layers of filter paper together, thus enabling the integrated fabrication of a three-dimensional microfluidic network. The finally formed microfluidic network includes an inlet, three branch channels, and three detection regions. The inlet is aligned with the inlet of the lower insulating paper layer, and the three detection regions cover the functional areas of the three electrode systems.

[0048] 2. Preparation of the electrochemical sensing unit

[0049] The carbon working electrode is immersed in chloroauric acid solution (1.0 mM), and a constant potential of -0.2 V is applied for 150 seconds (referred to as the Au / carbon electrode). For lactate and glucose determination, a constant potential (0.4 V) is applied for 100 seconds in a solution (100 mM potassium chloride, 100 mM hydrochloric acid, 2.5 mM potassium ferricyanide, and 2.5 mM ferric chloride) for Prussian blue deposition;

[0050] (1) Chloride ion determination: The working electrode is modified with a layer of Ag and then treated with ferric chloride (0.1 M) for 2 minutes. The Ag / AgCl reference electrode is drop-coated with a reference solution (50 mg sodium chloride, 79.1 mg polyvinyl butyral, and 1 mL methanol).

[0051] (2) Lactic acid determination: The chitosan solution (0.5 wt%) was prepared by dissolving chitosan powder in acetic acid (2 wt%). The lactate oxidase solution (30 mg mL -1 ) was obtained by dissolving lactate oxidase powder in PBS. The lactate oxidase solution was drop-coated on the working electrode and dried at 4 °C; this step was repeated once. Then, 2 μL of the chitosan solution was dropped on the working electrode and dried at 4 °C.

[0052] (3) Glucose determination: A mixture of glucose oxidase solution (10 mg mL -1 ) and chitosan solution (0.5 wt%) with a volume ratio of 1:2 was dropped on the working electrode, dried at 4 °C, and this process was repeated once. Finally, the glucose and lactate working electrodes were modified with a layer of Nafion (0.5%) and dried at 4 °C.

[0053] 3. Anti-interference performance of the device in Example 3

[0054] I. Experimental method

[0055] Common substances in sweat, NO3 - , Na + , K + , ascorbic acid, uric acid, and urea were selected as interfering substances, and relevant solutions were prepared and added to the analysis area of the device respectively.

[0056] II. Experimental results

[0057] The results are as Figure 3 shown. The device produces a significant electrical signal response to the target substance, while the signal changes caused by interfering substances can be ignored. The results show that within the 95% confidence interval, there is no statistically significant difference in the signals before and after adding the interfering substances, confirming that the device in Example 1 has excellent anti-interference performance.

[0058] 4. Anti-mechanical deformation ability of the device in Example 4

[0059] I. Experimental method

[0060] Investigate the change in electrical signal of the device under mechanical deformation (bending, stretching, and twisting).

[0061] II. Experimental results

[0062] The results are as Figure 4 shown. The electrical signal fluctuations caused by deformation recover quickly, indicating that the device has good ability to resist mechanical deformation.

[0063] 5. Stability of the device in Example 5

[0064] I. Experimental method

[0065] Place this device in an environment of 4°C and use a reagent containing chloride ions, glucose, and lactic acid (with a certain concentration and pH) to detect the signal changes of the sensor within 10 days.

[0066] II. Experimental Results

[0067] The results are as Figure 5 shown. The long-term stability of the sensing array was examined by tracking the signal changes within 10 days. During this period, the electrical signals of the three sensors remained almost unchanged, with an RSD of less than 5%, indicating long-term durability.

[0068] 6. Analysis of actual samples of the device in Example 6

[0069] I. Experimental Method

[0070] Volunteers were required to wear the developed device on their wrists and perform 30 minutes of cycling exercise. During the exercise, the sweat produced by the skin was transferred to the sensing area through the paper-based microfluidic network, thus enabling in-situ real-time analysis of sweat. The real-time data was transmitted to the user interface via Bluetooth.

[0071] II. Experimental Results

[0072] As Figure 6 shown, the concentration-time curve of the substances in the sweat of the volunteers is displayed. A signal was generated 15 minutes after the start of the exercise, and the device can achieve real-time sweat analysis and data transmission. The results indicate the feasibility of the present invention in actual sweat detection.

[0073] Finally, it should be noted that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat, characterized in that: These include three-dimensional paper-based microfluidic networks for sweat transport and electrochemical sensing arrays for sweat analysis. The three-dimensional paper-based microfluidic network layer includes two layers of filter paper, an insulating layer and two patterned polydimethylsiloxane layers; The electrochemical sensing array includes two three-electrode systems and one two-electrode system.

2. A three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat according to claim 1, characterized in that: The insulating layer is located on the lower filter paper and includes an inlet; The electrochemical sensing array is located on the insulating layer; The lower polydimethylsiloxane layer is located between the upper and lower filter papers, and serves as a hydrophobic barrier and adhesive. The structure includes an inlet, three branch channels, and three analysis areas. The inlet corresponds to the inlet of the insulating layer, and the three analysis areas respectively cover three sensing unit parts of the electrochemical sensor array. The upper polydimethylsiloxane layer comprises an inlet, three branch channels and three analysis areas, and is aligned with the inlet, three branch channels and three analysis areas of the lower polydimethylsiloxane layer, respectively.

3. A three-dimensional paper-based microfluidic electrochemical analysis device for in-situ monitoring of sweat according to claim 1, characterized in that: The detection liquid is sweat.

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