Passive driving microcapsule movement color development method

Abstract

The invention relates to a passive driving microcapsule movement color development method, and belongs to the field of sensor detection. According to the method, sweat generated during movement of a human body drives a photovoltaic device to spontaneously generate electric potential, the electric potential directly acts on microcapsule dispersion liquid to drive directional movement of black and white particles in the microcapsule dispersion liquid, and visual color development response without an external power source is achieved. The method mainly comprises the steps of sweat induced power generation, particle electrophoresis driving and ion concentration associated color development. The problems that an existing sweat detection technology depends on an external power source, the equipment size is large, and real-time visual reading cannot be achieved are solved, and the device is mainly applied to the fields of real-time sweat electrolyte analysis in exercise physiological monitoring, autonomous color development change of wearable medical equipment, passive sensing display integrated systems based on ion concentration gradient and the like.

Description

[Technical Field]

[0002] This invention relates to a passive method for driving microcapsule motion and color development. [Background Technology]

[0003] The hydrovoltaic effect refers to a physical phenomenon in which a potential difference is generated through the interaction between the solid and liquid interfaces when a fluid flows through nanomaterials. Based on this principle, hydrovoltaic devices can directly convert the kinetic and chemical energy of bodily fluids such as sweat secreted during human movement into electrical energy, providing a novel passive power supply solution for wearable sensing systems.

[0004] In the field of sweat physiological index detection, electrolyte ion concentration is an important parameter reflecting the body's hydration status and neuromuscular function. Traditional detection methods mainly rely on electrochemical sensors, which require external power supply and complex signal processing circuits, making it difficult to achieve convenient and intuitive visual readings. While display technology based on electrophoretic microcapsules can provide visual feedback, the particle movement usually requires an external power supply, resulting in low system integration and energy efficiency.

[0005] Current detection systems powered by external batteries require complex processes such as power management, signal conversion, and display driving. The sensing module needs initialization time and calibration procedures, and its overall power consumption is high. Subsequent data processing and transmission further complicate the real-time detection and visualization of motion in real-time applications. Existing solutions combining hydroelectric power generation with sensing often intermittently power traditional circuits through energy storage components. While this achieves some passive functionality, it still suffers from low energy conversion efficiency, slow response speed, inability to achieve direct particle electrophoresis driving, and high system complexity and insufficient reliability due to the introduction of electronic components. [Summary of the Invention]

[0006] The purpose of this invention is to provide a passively driven microcapsule motion color development method, which solves the problems of existing sweat detection technology relying on external power supply, low system integration, and inability to achieve real-time visual reading.

[0007] The technical solution of this invention is:

[0008] The passive-driven microcapsule motion color development method of the present invention includes the following steps:

[0009] (1) Construction of the water-voltaic device: A porous water-voltaic material with ion selectivity is selected as the core power generation unit to construct a micro water-voltaic device that can spontaneously generate potential using the flow of sweat; the construction method of the water-voltaic device includes:

[0010] (1.1) Pretreatment of water-based photovoltaic devices:

[0011] Take the prepared water-based device and check its electrode conductivity and structural integrity; rinse the internal flow channels or porous structure of the device with deionized water or low-concentration electrolyte solution to remove impurities remaining during the preparation process.

[0012] (1.2) Device performance optimization:

[0013] The pretreated water-voltaic device is placed in simulated sweat or buffer solution. A small external force is applied to drive the liquid to flow through the device, or it is left to stand to fully wet it. The open-circuit voltage and short-circuit current are measured until the output electrical signal is stable, thus obtaining a water-voltaic device that can be used immediately.

[0014] (2) Collection and pretreatment of sweat samples:

[0015] Collect naturally secreted sweat during human exercise, or use prepared simulated sweat as the test sample, and store it for later use;

[0016] (3) Sweat-driven colorimetric reaction:

[0017] (3.1) Pre-processing:

[0018] Take the activated water-based device from step (1) above, and correctly connect its output electrode to the microcapsule colorimetric unit prepared in step (2) to form a complete detection circuit;

[0019] (3.2) Reaction:

[0020] Contact the inlet or functional surface of the completed water-based device with the sweat sample from step (2) to allow the sweat to flow continuously and drive the device. Under room temperature conditions (15-35°C), after a reaction of 30-300 seconds, the water-based device spontaneously generates a potential difference of 0.1-5.0V based on the sweat flow. This potential is directly applied to the microcapsule colorimetric unit, driving the charged black and white particles inside to undergo directional electrophoretic motion, producing observable macroscopic visual changes, thus completing the passive colorimetric reaction based on the sweat ion concentration.

[0021] (4) Reading and interpreting the color development results:

[0022] Take the microcapsule colorimetric unit that has completed the colorimetric reaction in step (3.2) above, place it under standard light source conditions, and observe and measure the optical contrast of its colorimetric area; fit the obtained optical signal with the pre-established ion concentration-color intensity standard curve, and analyze the concentration value of the specific ion in the sweat sample that drives the color of the solution.

[0023] The aforementioned passive-driven microcapsule motion colorimetric method is characterized in that its implementation steps further include ion-selective functionalization modification of the water-voltaic device:

[0024] Before the water-voltaic device pretreatment in step (1.1), the core porous material is surface modified; functional molecules with specific selectivity for target ions are introduced by dip coating or vapor deposition, cured at 25-60℃ for 10-120 minutes, rinsed with deionized water and stored for later use.

[0025] Rinse the flow channels of the water-based device after testing with a cleaning buffer to remove residual sweat components; then briefly short-circuit the two ends of the colorimetric unit, or apply a reverse electric field of 0.5-5.0 V / mm for 10-60 seconds to drive the black and white particles in the microcapsules to return to their initial dispersion state, thereby resetting the system and making it ready for the next test.

[0026] The above-mentioned passively driven microcapsule motion color development method is characterized in that the method further includes an anti-interference sealing step for the color development unit:

[0027] After the colorimetric unit integration is completed in step (2.2), before the pretreatment in step (3.1), a surfactant is added to the microcapsule dispersion and allowed to stand for 30 to 90 minutes at 20 to 40°C. Then the dispersion medium is replaced to remove the unadsorbed surfactant.

[0028] The above-mentioned passively driven microcapsule motion color development method is characterized in that: the core porous material of the water-voltaic device is one of graphene oxide film, carbon nitride nanosheets, anodic aluminum oxide porous membrane or nanocellulose aerogel; the ion-selectively modified functional molecule is one or more of crown ether derivatives, ion carriers or two-dimensional materials with ion sieving effect.

[0029] The above-mentioned passively driven microcapsule motion colorimetric method is characterized in that: the sweat sample includes sweat naturally secreted by the human body during exercise or simulated sweat with predetermined composition; the target ions to be tested include sodium ions, potassium ions, chloride ions or calcium ions; the colorimetric unit includes electrophoretic microcapsules encapsulated with positively or negatively charged black and white particles, the particles including titanium dioxide white particles and carbon black black particles.

[0030] The above-mentioned passively driven microcapsule motion color development method is characterized by:

[0031] The simulated sweat is an aqueous solution with a pH of 4.0 to 7.0 containing 0.1–100 mM NaCl, 0.1–50 mM KCl, 0.01–10 mM CaCl2, and 0.1–20 mM lactic acid.

[0032] The washing buffer is one of deionized water, 0.1–10 mM Tris-HCl buffer, or 0.1–10 mM PBS buffer, with a pH of 5.0–8.0.

[0033] The surfactant used for the anti-interference blocking is one of Tween-20, Triton X-100, sodium dodecyl sulfate, or Pluronic F-127, and its mass percentage concentration in the dispersion is 0.01% to 1%.

[0034] The dispersion medium is one of silicone oil, dodecane, tetradecane, hexadecane, or isoelectric solvents from the Isopar series;

[0035] The reverse electric field used for resetting is provided by an external capacitor discharge circuit, with an electric field strength of 0.1–10 V / mm and an action time of 0.1–10 seconds.

[0036] The above-mentioned passively driven microcapsule motion color development method is characterized by:

[0037] The activation treatment of the water-voltaic device is carried out at 15-35°C for 10-60 minutes.

[0038] The sweat-driven colorimetric reaction is carried out at 15–35°C for 30–300 seconds.

[0039] The application time of the reverse electric field in the system reset and regeneration steps is 10 to 60 seconds;

[0040] The curing process for the ion-selective functionalization modification is carried out at 25–60°C for 10–120 minutes.

[0041] The anti-interference sealing treatment of the colorimetric unit is carried out at 20-40°C for 30-90 minutes.

[0042] The advantages of this invention are:

[0043] 1. Achieve truly passive drive

[0044] This invention utilizes the water voltaic effect to spontaneously generate electricity from the sweat secreted by the human body, driving the movement of particles inside the microcapsules without the need for an external power source or battery. This breaks through the dependence of traditional detection technologies on power sources and significantly improves the portability and wearing comfort of the device.

[0045] 2. Real-time visualization of test results

[0046] By using sweat to drive the electrophoretic movement of particles, macroscopic visual changes are generated directly, eliminating the need for signal conversion circuits or electronic displays. This enables intuitive and real-time reading of detection results, avoiding complex data processing.

[0047] 3. High system integration and rapid response.

[0048] The power generation unit is directly coupled to the display unit, eliminating the energy storage and management links and simplifying the system structure. A distinct color change response can be generated within 30 - 300 seconds after sweat contact, meeting the requirements for real-time monitoring.

[0049] 4. Wide applicability and reusability

[0050] By selecting different ion-selective modification materials, specific detection of various ions such as sodium, potassium, and chlorine can be achieved. The system has the ability to reset and regenerate, and can be restored to its initial state through simple cleaning and electrical reset, supporting multiple repeated uses.

[0051] 5. Significantly reduced detection cost

[0052] Components such as noble metal electrodes and precision circuits required for traditional electrochemical sensors are eliminated, and low-cost watervoltaic materials and electrophoretic microcapsules are used, greatly reducing the manufacturing cost and facilitating large-scale promotion and application. Description of the drawings

[0054] Figure 1 It is a schematic diagram of the overall drive device structure.

[0055] Figure 2 It is the display length at different voltages during the color change process of passive-driven microcapsules, where:

[0056] Legend 1 is the display length when the watervoltaic device provides a voltage of 0.72V during the color change process of passive-driven microcapsules;

[0057] Legend 2 is the display length when the watervoltaic device provides a voltage of 1.46V during the color change process of passive-driven microcapsules;

[0058] Legend 3 is the display length when the watervoltaic device provides a voltage of 2.18V during the color change process of passive-driven microcapsules;

[0059] Legend 4 is the display length when the watervoltaic device provides a voltage of 2.90V during the color change process of passive-driven microcapsules;

[0060] Legend 5 is the display length when the watervoltaic device provides a voltage of 3.63V during the color change process of passive-driven microcapsules;

[0061] Legend 6 is the display length when the watervoltaic device provides a voltage of 4.31V during the color change process of passive-driven microcapsules;

[0062] Legend 7 is the display length when the watervoltaic device provides a voltage of 5.11V during the color change process of passive-driven microcapsules;

[0063] Figure 8 shows the length displayed when the water-voltaic device provides a 5.80V voltage during the passively driven microcapsule movement and color development process;

[0064] Figure 9 shows the length displayed when the water-voltaic device provides a voltage of 7.26V during the passively driven microcapsule movement and color development process. Detailed Implementation

[0066] Example 1 is a passive colorimetric process based on sweat-driven sodium ion concentration detection:

[0067] 1. Fabrication and Functional Modification of Water-Based Photovoltaic Devices: A 1cm × 2cm porous graphene oxide film was symmetrically encapsulated with carbon wire electrodes on both sides to form a basic water-based photovoltaic device. The film was surface-modified using a 0.1mM crown ether derivative solution, and allowed to stand at 40℃ for 60 minutes. After rinsing three times with deionized water, a sodium-ion selective water-based photovoltaic device was obtained.

[0068] a. Assembly and sealing of the colorimetric unit: 100 μl of electrophoretic microcapsules containing negatively charged white titanium dioxide particles and carbon black particles were uniformly dispersed in 1 ml of tetradecane dispersion medium. The dispersion was injected into a microcavity (10 mm × 10 mm × 0.5 mm) equipped with an ITO transparent electrode and sealed to form the colorimetric unit. 0.1% Tween-20 surfactant was added, and the unit was sealed at 25 °C for 60 minutes, after which the dispersion medium was replaced with fresh medium.

[0069] b. System Integration and Performance Verification: The output electrode of the water-based photovoltaic device was directly connected to the ITO electrode of the colorimetric unit. A 200 μl sample of sweat collected from healthy volunteers during exercise was added to the inlet of the water-based photovoltaic device. At room temperature (25°C), the sweat flowed naturally through the device's microchannels, generating a stable output voltage of 0.72V within 120 seconds. This drove the white particles within the microcapsules to aggregate towards the anode, reducing the grayscale value of the display area from an initial 85 to 42.

[0070] 2. Colorimetric detection of sodium ion concentration driven by sweat:

[0071] a. Sweat sample pretreatment: Take 50 μl of fresh sweat sample secreted by the human body during exercise, and use it directly for detection without dilution.

[0072] b. Connect the water-based device prepared in step 1 with the colorimetric unit through wires to form a complete detection circuit; add the sweat sample from step a to the inlet of the water-based device and react for 120 seconds at room temperature (25°C). When the sweat flows through the functionalized porous membrane, it generates an output voltage of 0.72V, which drives the charged particles in the colorimetric unit to undergo electrophoretic motion, thereby realizing the colorimetric response.

[0073] c. Colorimetric signal acquisition: The gray value of the colorimetric unit is measured using a portable grayscale meter. The measured value drops from the initial 85 to 42, indicating that the colorimetric reaction is complete.

[0074] 3. Quantitative analysis of test results:

[0075] The grayscale value of 42 obtained in step 2c was input into a pre-established sodium ion concentration-grayscale value standard curve, and the calculated sodium ion concentration in sweat was 45 mM. To verify accuracy, the same sample was simultaneously tested using ion chromatography, and the result was 43 mM, with a relative error of 4.7%, proving that this method has reliable detection accuracy.

[0076] 4. System Reset and Regeneration:

[0077] After detection, the flow channels of the water-based device were rinsed with 0.5 ml of PBS buffer (pH 7) to remove residual sweat. Then, the two electrodes of the colorimetric unit were directly connected to an external power supply to restore the particles to their initial dispersion state. The system grayscale value returned to 84, ready for the next detection. Testing showed that the system is reusable with no significant performance degradation.

[0078] Example 2 illustrates a passive colorimetric process for potassium ion concentration detection using a water-based photovoltaic device modified with an ion carrier:

[0079] 1. Preparation and Functional Modification of Potassium-Selective Aqueous Photovoltaic Devices: A porous film of carbon nitride nanosheets with dimensions of 1 cm × 2 cm was symmetrically encapsulated with gold electrodes on both sides to construct a basic aqueous photovoltaic device. A tetrahydrofuran solution with a concentration of 0.5 mg / ml was prepared using calixarene derivatives. 500 μl of the solution was uniformly coated onto the film surface and dried at 50 °C for 30 minutes to obtain potassium-selective modified aqueous photovoltaic devices. The devices were rinsed three times with PBS buffer at approximately pH 6 and stored in a preservation solution (deionized water containing 0.05% NaN3) for later use.

[0080] 2. Assembly and Optimization of the Dedicated Colorimetric Unit: Positively charged white titanium dioxide particles and negatively charged carbon black particles were mixed at a mass ratio of 3:1 and dispersed in 1 ml of Isopar G dispersion medium. The mixed dispersion was injected into a specially designed dual-chamber colorimetric unit, which employs an ITO-PET flexible electrode structure. 0.05% Pluronic F-127 surfactant was added, and the unit was sealed at 30°C for 45 minutes, after which the dispersion medium was replaced with fresh material.

[0081] 3. Integration and Validation of the Potassium Ion Detection System: The functionalized water-based photovoltaic device and the optimized colorimetric unit were connected via a flexible circuit. A 150 μl sweat sample collected during exercise physiology studies was added to the device's detection area. At room temperature (28°C), the sweat flowed between the nanosheet layers, generating a stable 0.6V output voltage within 90 seconds. This drove white particles to aggregate towards the negative electrode, significantly improving the contrast of the display area. The grayscale value decreased from an initial 82 to 38, corresponding to a potassium ion concentration of 8.2 mM in the sweat.

[0082] 4. Preparation and Functional Modification of Chloride Ion-Selective Aqueous Photovoltaic Devices: A porous anodic alumina membrane measuring 1.5 cm × 1.5 cm was symmetrically encapsulated with carbon wire electrodes on both sides to construct a basic aqueous photovoltaic device. An ion-carrier solution was prepared as a 0.2 mg / ml methanol solution, and 800 μl was uniformly coated onto the membrane surface. The membrane was then vacuum-dried at 25°C for 20 minutes to obtain chloride ion-selectively modified aqueous photovoltaic devices. The devices were rinsed twice with pH 7.0 PBS buffer and stored in a preservation solution (deionized water containing 0.01% mercuric sulfate) for later use.

[0083] 5. Assembly and Optimization of the Dedicated Colorimetric Unit: Positively charged white titanium dioxide particles and negatively charged carbon black particles were mixed at a mass ratio of 2:1 and dispersed in 1.5 ml of silicone oil dispersion medium. The mixed dispersion was injected into a modified three-chamber colorimetric unit (12 mm × 12 mm × 0.4 mm), which adopted a flexible indium tin oxide electrode structure. 0.2% Triton X-100 surfactant was added, and the unit was sealed at 35°C for 60 minutes, after which the dispersion medium was replaced with fresh material.

[0084] 6. Integration and Validation of the Chloride Ion Detection System: The functionalized water-based photovoltaic device and the optimized colorimetric unit were connected via flexible wires. A 180 μl sweat sample collected during the sports endurance test was uniformly coated onto the device's detection area. At room temperature (30°C), the sweat flowed through the alumina nanopores, generating a stable 0.45V output voltage within 150 seconds. This drove black particles to aggregate towards the positive electrode, increasing the grayscale value of the display area from an initial 78 to 65, corresponding to a chloride ion concentration of 35 mM. Validation using ion chromatography confirmed the chloride ion concentration of the sample to be 36 mM, with a relative error of 2.8%.

[0085] 7. Resetting and Saving the Detection System: After detection, rinse the microporous structure of the water-based device with 1 ml of buffer solution diluted with HCl (pH approximately 7) to remove residual sweat components; reverse the connection between the two electrodes of the colorimetric unit and the DC power supply to drive the particles back to their initial dispersion state, restoring the system grayscale value to 79. Finally, place the entire system in a dedicated storage box and store it at room temperature in a dry place for future detection. Actual testing has shown that the system can be stably and repeatedly used.

[0086] The technical solution of this invention is not limited to the above embodiments. The core porous material of the water-voltaic device can also be other polymer membrane materials. The target detection ions include not only sodium ions, potassium ions, and chloride ions, but can also be extended to important physiological indicators in sweat such as calcium ions, magnesium ions, and lactate ions. The sweat sample sources include not only human secretion during exercise, but also sweat samples under pathological conditions or artificially prepared standard sweat. The charged particle material is not limited to titanium dioxide and carbon black, but also includes other organic or inorganic colorimetric particles with electrophoretic properties. In addition to being used independently, the technical solution can also be integrated with flexible circuits and near-field communication modules to realize wireless data transmission and processing.

Claims

1. A passively driven microcapsule motion color development method, characterized in that, Includes the following steps: Step S1: Construct a water-based photovoltaic device, which includes an ion-selective porous water-based photovoltaic material for spontaneously generating an electric potential using sweat flow; Step S2: Prepare a colorimetric microcapsule unit, which includes an electrophoretic microcapsule encapsulating charged black and white particles; Step S3: Attach the water-based photovoltaic device to a sweat-prone area of ​​the human body, allowing sweat to flow into the water-based photovoltaic device to generate a potential difference, and apply this potential difference to the colorimetric microcapsule unit; Step S4: Under the action of the potential difference, the black and white particles undergo directional electrophoretic motion, causing a change in the macroscopic optical state of the colorimetric microcapsule unit; Step S5: Compare the colorimetric state of the colorimetric microcapsule unit with a preset concentration-colorimetric standard curve to obtain the detection result of the specific ion concentration in the sweat.

2. The method according to claim 1, characterized in that, Step S1 includes: pre-treating the water-voltaic device by rinsing its internal channels or porous structure with deionized water or a low-concentration electrolyte solution; placing the pre-treated water-voltaic device in simulated sweat or a buffer solution and measuring its open-circuit voltage and short-circuit current until the output electrical signal stabilizes. The method according to claim 1, characterized in that, Step S2 includes: uniformly dispersing electrophoretic microcapsules in a dispersion medium with matching dielectric constant to form a microcapsule dispersion; encapsulating the microcapsule dispersion in a microcavity with a transparent observation window and electrodes to form the colorimetric microcapsule unit; and connecting the colorimetric microcapsule unit to the output electrode of the water-voltaic device through a conductive line. The method according to claim 1, characterized in that, The steps preceding step S1 also include...

3. The core porous material of the water-voltaic device is ion-selectively modified by introducing functional molecules or polymers that are selective for target ions. The method according to claim 1, characterized in that, Step S5 is followed by: separating the water-based device and the colorimetric microcapsule unit from the sweat sample; rinsing the flow channel of the water-based device with a cleaning buffer or deionized water; and applying a reverse electric field to the colorimetric microcapsule unit to drive the black and white particles back to their initial dispersed state.

4. The method according to claim 3, characterized in that, after step S2, it further includes: adding a surfactant or stabilizer to the microcapsule dispersion and allowing it to stand for 30 to 60 minutes at 25±5℃.

5. The method according to claim 1, wherein the core porous material of the water-voltaic device is one of graphene oxide film, carbon nitride nanosheets, anodic alumina porous membrane, or nanocellulose aerogel; the ion-selectively modified functional molecule is one or more of crown ether derivatives, ion carriers, or two-dimensional materials with ion sieving effects. The method according to claim 1, wherein the simulated sweat is an aqueous solution with pH 4.0-7.0 containing 0.1-100 mM NaCl, 0.1-50 mM KCl, 0.01-10 mM CaCl2, and 0.1-20 mM lactic acid; the washing buffer is one of deionized water, 0.1-10 mM HCl buffer, or 0.1-10 mM PBS buffer, with a pH of 5.0-8.

0.

6. The method according to claim 6, characterized in that: The surfactant is one of Tween-20, Triton X-100, or sodium dodecyl sulfate, and its mass percentage concentration in the dispersion is 0.01% to 1%; the dispersion medium is one of silicone oil, dodecane, tetradecane, or hexadecane.

7. The method according to claim 5, characterized in that: The electric field strength of the reverse electric field is 0.1–10 V / mm, and the duration of action is 0.1–10 seconds.

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