Partitioned double-sided skin-adhesive sweat-repellent hybrid energy harvesting armband and preparation method thereof

Abstract

This invention relates to the field of wearable electronic device technology, specifically disclosing a partitioned, double-sided, skin-contact, sweat-wicking hybrid energy harvesting armband and its manufacturing method. The armband includes a flexible strip substrate, an organic photovoltaic (PV) power generation unit, a polymer thermoelectric power generation unit, a skin-contact thermal interface layer, a cold-end heat dissipation structure, and a circuit integration module. The PV power generation unit and the polymer thermoelectric power generation unit are partitioned and mounted on the same flexible strip substrate. Microstructured channels are pre-set within the skin-contact thermal interface layer to guide sweat and reduce contact thermal resistance. A process route is adopted where the organic PV is first fabricated and encapsulated with high barrier properties, followed by the printing of the polymer thermoelectric power generation unit. A porous fabric or fin array heat dissipation structure is integrated at the cold end of the polymer thermoelectric power generation unit. This invention can improve photoelectric conversion efficiency, stabilize operating temperature difference, reduce contact thermal resistance, increase manufacturing yield, enhance output power, and improve wearing comfort.

Description

Technical Field

[0001] This invention relates to the field of wearable electronic device technology, specifically to a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband and its preparation method. Background Technology

[0002] As wearable electronic devices rapidly evolve towards lighter weight, greater flexibility, and longer wearability, a continuous and stable energy supply has become a core bottleneck restricting their functional expansion and user experience improvement. Currently, hybrid energy harvesting technology, by integrating multiple energy conversion mechanisms such as organic photovoltaics (OPV) and thermoelectric power generation (TEG), aims to utilize ambient light and waste heat from the human body for synergistic energy supply, and has shown application potential in scenarios such as smart bracelets and health monitoring patches. This technological approach relies on the efficient capture and conversion of light and heat energy, and its performance is highly limited by multiple factors such as device structure layout, interface thermal management, process compatibility, and mechanical reliability. These challenges are particularly pronounced in dynamic usage environments where the device is in close contact with the skin.

[0003] Among them, hybrid energy harvesting devices integrating OPV and TEG on flexible strip substrates have become a research hotspot. The basic principle is to use OPV to capture ambient light to generate electricity, while using TEG to perform thermoelectric conversion based on the temperature difference between the skin and the environment. However, existing technologies generally adopt the integration method of OPV and TEG overlapping or tightly stacking in space, which leads to serious coupling interference between the two at the thermal and process levels.

[0004] Existing technologies suffer from several irreconcilable contradictions: First, OPV is temperature-sensitive, and if the TEG cold-end heat dissipation structure is close to the OPV area, it will heat it, leading to a significant decrease in OPV photoelectric conversion efficiency. Simultaneously, the heat generated by OPV operation disrupts the stable temperature difference required by the TEG, causing output power fluctuations. Second, during prolonged wear, sweat accumulation at the skin-contact interface forms air gaps or liquid films, significantly increasing thermal resistance and preventing the TEG hot end from effectively coupling with skin temperature, resulting in a sharp decline in thermoelectric performance. Third, OPV devices are typically composed of organic active layers, which are extremely sensitive to solvents, high temperatures, and mechanical stress. Subsequent TEG printing or bonding processes can easily cause irreversible damage, leading to low yield rates. Furthermore, flexible devices undergo repeated deformation during arm bending movements; if critical wires are not properly positioned in the strain neutral layer, they are prone to breakage, affecting long-term power supply stability. More critically, traditional skin-contact interfaces lack active sweat wicking and breathability designs, which not only exacerbate thermal resistance drift but also cause stuffiness and discomfort, severely limiting the wearability and user compliance of the device. The aforementioned issues collectively constitute a comprehensive technical obstacle to hybrid energy harvesting wearable devices in terms of efficiency, stability, reliability, and comfort, urgently requiring a wearable electronic device that takes into account thermal management, process isolation, structural partitioning, and physiological adaptation to achieve a breakthrough. Summary of the Invention

[0005] This invention provides a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband and its preparation method, aiming to solve the problems existing in the prior art, such as thermal interference caused by the spatial overlap of organic photovoltaic power generation units and polymer thermoelectric power generation units, increased thermal resistance due to sweat accumulation at the skin-adhering interface, low yield due to poor process compatibility between organic photovoltaic power generation units and polymer thermoelectric power generation units, low mechanical reliability due to the failure of key wires to be arranged in the strain neutral layer, and poor wearing comfort due to the lack of sweat-wicking design at the skin-adhering interface.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband is provided, comprising: a flexible strip-shaped substrate, which is divided along its length into a first region and a second region that do not overlap spatially; an organic photovoltaic power generation unit disposed on the outer surface of the flexible strip-shaped substrate in the first region for capturing ambient light energy and converting it into electrical energy; a polymer thermoelectric power generation unit disposed on the inner surface of the flexible strip-shaped substrate in the second region for utilizing the temperature difference between the skin and the environment for thermoelectric conversion; and a skin-adhering thermally conductive interface layer covering the hot end surface of the polymer thermoelectric power generation unit. It features a pre-designed microstructure channel, which is distributed in an interconnected grid or radial pattern to achieve close contact with the skin, facilitate sweat drainage, and reduce and stabilize contact thermal resistance; a cold-end heat dissipation structure, which is disposed on the outer surface of the flexible strip substrate and corresponds to the cold end position of the polymer thermoelectric power generation unit, to enhance heat exchange between the cold end of the polymer thermoelectric power generation unit and the ambient air; and a circuit integration module, which electrically connects and manages the output of the organic photovoltaic power generation unit and the polymer thermoelectric power generation unit through flexible wires arranged near the strain neutral layer.

[0008] Preferably, the flexible strip substrate is made of polyimide or polyethylene terephthalate material with a thickness ranging from 50 μm to 200 μm. The length ratio of the first region to the second region is between 0.8 and 1.2, and there is a physical isolation strip with a width of not less than 2 mm between the two regions. No functional layer is provided in the isolation strip to ensure complete thermal and process isolation between the organic photovoltaic power generation unit and the polymer thermoelectric power generation unit.

[0009] Furthermore, the organic photovoltaic power generation unit includes a transparent conductive electrode, an organic active layer, and a metal back electrode sequentially stacked on the outer side of the first region of the flexible strip substrate. The organic active layer has a bulk heterojunction structure, consisting of a donor material PTB7-Th and an acceptor material PC. 71The organic photovoltaic power generation unit is composed of BM blends with a thickness of 100nm to 200nm. The surface of the organic photovoltaic power generation unit is covered with a high-barrier encapsulation layer, which is a 3 to 5 layer stacked structure formed by alternating deposition of Al2O3 and Parylene.

[0010] Furthermore, the polymer thermoelectric power generation unit consists of an array of multiple p-type and n-type thermoelectric arms arranged alternately in series. The p-type thermoelectric arms are made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate; the n-type thermoelectric arms are made of doped and modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate. The thermoelectric arms are formed on the inner surface of the second region of the flexible strip substrate by printing or coating processes, and are electrically interconnected by silver paste or conductive polymer ink to form a complete power generation circuit.

[0011] Furthermore, the skin-conducting thermal interface layer is composed of a biocompatible ultrathin hydrogel with a thickness of 5 μm to 20 μm and a Young's modulus between 1 kPa and 100 kPa to match the mechanical properties of the skin. The microstructure channels are formed within the hydrogel layer by laser etching or molding processes. The cross-section of the microstructure channels is rectangular or trapezoidal, with a width of 50 μm to 200 μm and a depth of 5 μm to 20 μm. The depth of the microstructure channels is less than the thickness of the skin-conducting thermal interface layer, and the spacing between adjacent channels is 200 μm to 600 μm, forming a network for guiding the capillary flow of sweat and the expulsion of gas.

[0012] Preferably, the cold-end heat dissipation structure is a porous fabric heat sink or a thin metal fin array. The porous fabric heat sink is woven from polyester or cotton fibers with a porosity greater than 70%, and is bonded to the outer surface of the second region of the flexible strip substrate by a hot-pressing process. The thin metal fin array is made of copper or aluminum foil with a thickness of 0.1 mm to 0.3 mm by photolithography and etching processes, with a fin height of 1 mm to 3 mm, and is fixed by thermally conductive adhesive. Specifically, a three-dimensional woven polyester fiber fabric with a mesh size of 200-400 is used, and the diameter of a single fiber is 10-30 μm.

[0013] Furthermore, the circuit integration module includes a dual-source rectifier circuit, a maximum power point tracking circuit, and an energy storage unit. The flexible conductor is a copper-polyimide laminated conductor or a silver nanowire conductive ink printed conductor, and its wiring path is designed to be closely attached to the strain-neutral layer of the flexible strip substrate. The position of the strain-neutral layer is determined by the formula... Confirmed, among which , and These represent the Young's modulus, cross-sectional area, and distance to the reference surface for each functional layer.

[0014] On the other hand, a method for preparing a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband is provided, the specific steps of which are as follows:

[0015] Step S1: Provide a flexible strip substrate and divide it into a first region and a second region that do not overlap along its length.

[0016] Step S2: In the first region on the outer surface of the flexible strip substrate, a transparent conductive electrode is sequentially deposited, an organic active layer is spin-coated, and a metal back electrode is vapor-deposited to form an organic photovoltaic power generation unit.

[0017] Step S3: The organic photovoltaic power generation unit is encapsulated with high barrier properties by alternating atomic layer deposition and chemical vapor deposition processes to form a stacked encapsulation structure of Al2O3 and Parylene.

[0018] Step S4: In the second region on the inner surface of the flexible strip substrate, p-type thermoelectric ink (poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) and n-type thermoelectric ink (such as doped and modified poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) are sequentially coated by screen printing. After patterning and heat treatment, an array of alternating p-type and n-type thermoelectric arms is formed. The electrical interconnection of adjacent p-type and n-type thermoelectric arms is completed by using conductive paste to construct a polymer thermoelectric power generation unit.

[0019] Step S5: Coat the hot end surface of the polymer thermoelectric power generation unit with an ultra-thin hydrogel precursor. After curing with ultraviolet light, use laser etching process to process microstructure channels with a preset pattern in the cured hydrogel layer to form a skin-friendly thermally conductive interface layer.

[0020] Step S6: On the outer surface of the flexible strip substrate, at a position corresponding to the cold end of the polymer thermoelectric power generation unit, a porous fabric heat sink or thin metal fin array is hot-pressed and bonded to form a cold end heat dissipation structure.

[0021] Step S7: The flexible wires are wired along the strain neutral layer of the flexible strip substrate, and the output terminals of the organic photovoltaic power generation unit and the polymer thermoelectric power generation unit are welded to the dual-source rectification and power management circuit to complete the arm strip integration.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention achieves complete isolation of physical space and thermal path by partitioning and faceting the organic photovoltaic power generation unit and the polymer thermoelectric power generation unit on the same flexible strip substrate. This eliminates the coupling interference caused by the cold end heat dissipation heating of OPV and the self-heating of OPV interfering with the temperature difference of polymer thermoelectric power generation unit, thereby improving the photoelectric conversion efficiency of OPV.

[0024] 2. The microstructure channels preset in the skin-conducting thermal interface layer of the present invention can actively guide sweat and expel air through capillary action, transforming the random air gaps / liquid films formed by sweat accumulation into controllable low thermal resistance conduction pathways, thereby reducing the contact thermal resistance between the skin and the hot end of the thermoelectric unit, and the thermal resistance fluctuation amplitude is small during long-term wear.

[0025] 3. The present invention adopts a process route of first completing OPV preparation and high-barrier encapsulation, and then printing polymer thermoelectric power generation units and subsequent integration. The high-barrier encapsulation layer protects OPV from solvent and high-temperature damage in subsequent processes, thereby improving yield. It completely protects OPV devices that are sensitive to solvents and high temperatures, avoiding damage from subsequent processes, and thus improving the yield of hybrid device preparation.

[0026] 4. This invention significantly increases the convective heat transfer area and efficiency between the cold end and the air by integrating a porous fabric or fin array heat dissipation structure at the corresponding position of the cold end of the polymer thermoelectric power generation unit, thereby enhancing the temperature gradient required by the polymer thermoelectric power generation unit and improving the output power of the polymer thermoelectric power generation unit module.

[0027] 5. By precisely arranging the key flexible conductor near the strain neutral layer determined by the modulus and thickness of each material layer, the present invention ensures long-term mechanical reliability by minimizing the tensile / compressive strain borne by the conductor when the arm is repeatedly bent and deformed.

[0028] 6. The base, encapsulation, interface layer and thermoelectric materials used in the armband of the present invention all meet biocompatibility standards. Combined with a microstructure interface with sweat-wicking and breathable function, the microstructure channel actively guides sweat to avoid the formation of air gaps / liquid films, thereby reducing contact thermal resistance, significantly improving wearing comfort and safety, and supporting long-term, imperceptible wearing of the device. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband proposed in this invention.

[0030] Figure 2 This is a schematic diagram of the overall structure of the partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband proposed in this invention.

[0031] In the above attached diagram, the component numbers are as follows:

[0032] 1. Flexible strip substrate; 2. Physical isolation strip; 3. Organic photovoltaic power generation unit; 4. Polymer thermoelectric power generation unit; 5. Skin-friendly thermally conductive interface layer; 6. Cold end heat dissipation structure; 7. Circuit integration module; 8. Flexible wire. Detailed Implementation

[0033] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0034] Example 1

[0035] In the field of wearable health monitoring and IoT node power supply, especially in scenarios requiring long-term continuous operation such as outdoor sports, medical monitoring, or fieldwork, the demand for self-powered devices is extremely urgent. Traditional single energy harvesting methods, such as photovoltaics or thermoelectrics, are limited by the fluctuations in environmental conditions (such as light intensity and temperature difference), making it difficult to provide stable and continuous power. This invention provides a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband and its manufacturing method. It aims to achieve efficient, stable, and comfortable energy harvesting by integrating organic photovoltaic power generation units and polymer thermoelectric power generation units, and optimizing their spatial layout, thermal management, and interface characteristics, thus providing a reliable power solution for low-power wearable electronic devices.

[0036] See Figure 1 and Figure 2 This armband includes a flexible strip substrate 1, an organic photovoltaic power generation unit 3, a polymer thermoelectric power generation unit 4, a skin-conducting thermal interface layer, a cold-end heat dissipation structure, and a circuit integration module. The flexible strip substrate 1 serves as the main load-bearing component of the armband; its material selection, structural division, and mechanical design are fundamental to ensuring the armband's flexibility and functional isolation. In this embodiment, the flexible strip substrate 1 uses a 100μm thick polyimide film, which possesses excellent mechanical strength, thermal stability, and electrical insulation. Along the length of the substrate, two spatially non-overlapping regions—a first region and a second region—are precisely divided using laser marking or masking processes. The length ratio of the first region to the second region is designed to be 1:1, and a 3mm wide physical isolation strip 2 exists between them. No functional materials are deposited within this isolation strip, maintaining the original state of the substrate material. This design completely isolates the organic photovoltaic power generation unit 3 and the polymer thermoelectric power generation unit 4 in physical space, avoiding mutual contamination of materials and solvents in subsequent processes. More importantly, it establishes an independent thermal path for the two, preventing performance coupling interference caused by the cold end heat dissipation heating the organic photovoltaic power generation unit 3 or the self-heating of the organic photovoltaic power generation unit 3 interfering with the temperature difference of the polymer thermoelectric power generation unit 4.

[0037] The organic photovoltaic power generation unit 3 is responsible for capturing ambient light energy and converting it into electrical energy. This unit is located in the first region on the outer surface of the flexible strip substrate 1. Its fabrication begins by depositing a 150 nm thick indium tin oxide (ITO) transparent conductive electrode on the outer side of the clean substrate's first region using a magnetron sputtering process. This electrode has high transmittance and low sheet resistance, serving as the anode of the device. Subsequently, an organic active layer is fabricated on the ITO electrode using a spin-coating process. The organic active layer employs a bulk heterojunction structure, consisting of a donor material PTB7-Th and an acceptor material PC. 71 BM was dissolved in chlorobenzene solvent at a weight ratio of 1:1.5, spin-coated into a film, and annealed at 100°C for 10 minutes to form a uniform film with a thickness of approximately 150 nm. This active layer is responsible for absorbing photons and generating excitons, which are then separated into free charges. Finally, a 100 nm thick aluminum back electrode was deposited on the organic active layer using a thermal evaporation process to serve as the cathode of the device, completing the basic structure of the organic photovoltaic power generation unit 3. To protect the organic active layer, which is extremely sensitive to water and oxygen, high-barrier encapsulation is necessary. In this embodiment, an alternating process of atomic layer deposition (ALD) and chemical vapor deposition (CVD) is used for encapsulation. First, an aluminum oxide film with a thickness of 25 nm is deposited on the surface of the complete organic photovoltaic power generation unit 3 using ALD. This film is dense and free of pinholes. Subsequently, a 2 μm thick parylene film is deposited using CVD. This process is repeated twice to finally form a five-layer stacked encapsulation structure consisting of "alumina-parylene-alumina-parylene-alumina". Tests showed that the water vapor transmission rate of this encapsulation structure was less than 1×10⁻⁶. -5 g / (m 2 ·day), effectively ensuring the long-term working stability of the organic photovoltaic power generation unit 3 in a humid environment.

[0038] The polymer thermoelectric power generation unit 4 is responsible for thermoelectric conversion using the temperature difference between the human skin surface and the ambient air. This unit is located in the second region of the inner surface of the flexible strip substrate 1. The polymer thermoelectric power generation unit 4 consists of an array of multiple p-type and n-type thermoelectric arms arranged alternately in series. The p-type thermoelectric arm material is poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, with a Seebeck coefficient greater than 20 μV / K; the n-type thermoelectric arm material is doped and modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate. Specifically, polyethyleneimine (PEI, molecular weight 800~2000) is used as the n-type dopant, and its tertiary amine groups can neutralize the polystyrene sulfonate (PSS) in PEDOT:PSS through deprotonation. -This process reduces the hole carrier concentration, while the PEI molecular chain forms hydrogen bonds with the PEDOT chain segment, suppressing hole transport and achieving n-type conductivity. Pre-soaking with sodium hydroxide (NaOH, 0.1~0.5 mol / L aqueous solution) further promotes PSS... - The removal of PEI enhances n-type stability. The modification steps are as follows: S10, the printed PEDOT:PSS film (20~30μm thick) is vacuum dried at 60℃ for 1 hour to remove residual solvent. S20, a 5~8wt% PEI ethanol solution is prepared, and the film is completely immersed in it. It is then allowed to stand at 25℃ for 30~60 seconds, during which time magnetic stirring (200rpm) is used to ensure uniform contact. S30, the PEI-treated film is transferred to a 0.2mol / L NaOH aqueous solution and immersed for 10~15 seconds. After rinsing three times with deionized water, it is dried with nitrogen. S40, the modified film is annealed on a hot plate at 80~100℃ for 15~20 minutes to promote the interfacial bonding between PEI and PEDOT segments and remove residual moisture.

[0039] In the fabrication process, p-type and n-type thermoelectric inks are first alternately coated onto the inner surface of the second region of a flexible strip substrate 1 using a screen printing process, forming multiple strip-shaped thermoelectric arm precursors according to a preset pattern. After patterning, a heat treatment at 120°C for 30 minutes is performed to remove residual solvents and enhance the conductivity of the film, forming stable p-type and n-type thermoelectric arms. Each thermoelectric arm has dimensions of 10 mm in length, 1 mm in width, and 20 μm in thickness. The spacing between the thermoelectric arms is 0.5 mm. Subsequently, using a screen printing process, silver conductive paste is used to print connections at the ends of adjacent p-type and n-type thermoelectric arms, forming electrical interconnections. All thermoelectric arms are connected in series to form a complete power generation circuit. The series design allows for the accumulation of higher output voltage within a smaller area, which is more conducive to the management of subsequent circuits.

[0040] The skin-conducting thermal interface layer 5 is a key component for achieving efficient thermoelectric conversion and wearing comfort, covering the hot-end surface of the polymer thermoelectric power generation unit 4. This layer is composed of a biocompatible ultrathin hydrogel; in this embodiment, a polyvinyl alcohol-glycerol hydrogel with a thickness of 15 μm and a Young's modulus of approximately 10 kPa is used. This hydrogel highly matches the mechanical properties of human skin, ensuring a pressure-free fit and allowing it to deform with the skin. The pre-designed microstructure channels within the interface layer are fabricated using an ultraviolet laser etching process. These microstructure channels are radially distributed, with their ends extending to the edge of the flexible strip-shaped substrate. Openings at the edges allow sweat to be discharged and evaporated via air convection. Specifically, after coating the hydrogel precursor and curing it with ultraviolet light, a 355 nm ultraviolet laser is used to scan and etch the surface according to a pre-designed grid pattern. The etched microstructure channels have a trapezoidal cross-section with an upper base width of 100 μm, a lower base width of 150 μm, and a depth of 13–14 μm, leaving a 1–2 μm hydrogel underlayer as a buffer. The center-to-center spacing between adjacent channels is 400 μm, thus forming a dense, interconnected capillary network within the interface layer. When the arm sweats, liquid sweat is rapidly absorbed under capillary force and directionally guided along the microstructure channels to the edge region for evaporation. Simultaneously, the random air gaps between the skin surface and the hot end of the thermoelectric unit, formed by sweat evaporation or residual air, are orderly replaced by the channel structure. This process transforms the unstable, high-thermal-resistance random interface into a controllable, low-thermal-resistance stable heat conduction pathway, significantly reducing contact thermal resistance. Simulations and measurements show that after adopting this microstructure interface layer, the steady-state contact thermal resistance between the skin and the hot end of the thermoelectric unit is reduced by 35%, and after one hour of moderate-intensity exercise, the thermal resistance fluctuation is less than 8%.

[0041] The cold-end heat dissipation structure 6 is disposed on the outer surface of the flexible strip substrate 1 and precisely corresponds to the cold end position of the polymer thermoelectric power generation unit 4. Its function is to enhance the heat exchange between the cold end and the ambient air, and maintain and expand the temperature gradient required for thermoelectric conversion. In this embodiment, a porous fabric heat sink is selected as the heat dissipation structure. The heat sink is made of polyester fiber through a three-dimensional weaving process, with a porosity of 75% and a thickness of 2 mm. Through a hot-pressing process, a low-temperature hot melt adhesive film is used to firmly attach the porous fabric heat sink to the outer surface of the second region of the flexible strip substrate 1, covering the entire projected area of ​​the polymer thermoelectric power generation unit 4. The porous structure greatly increases the contact area with air and promotes natural air convection by utilizing the gaps between fibers. When the arm swings or there is a breeze, the air can flow more effectively through the heat sink, carrying away the heat from the cold end. As another optional solution, a thin metal fin array can also be used, such as an array of fins with a height of 2 mm made of 0.2 mm thick copper foil through photolithography and chemical etching, which is fixed by high thermal conductivity silicone. It relies on the high thermal conductivity of the metal and the expanded surface area of ​​the fins to enhance heat dissipation.

[0042] The circuit integration module 7 is responsible for collecting, managing, and storing the electrical energy generated by the two power generation units. This module includes a dual-source rectifier circuit, a maximum power point tracking circuit, and a solid-state thin-film lithium battery as an energy storage unit. The outputs of the organic photovoltaic power generation unit 3 and the polymer thermoelectric power generation unit 4 are connected to the circuit integration module 7 via flexible wires 8. Vias are formed at the physical isolation strip 2 of the flexible strip substrate 1 through mechanical punching or laser drilling, and conductive silver paste is filled into the vias to form vertical interconnect pathways, enabling communication between the inner and outer electrodes. After filling with conductive paste, a secondary encapsulation around the via edges is performed using UV adhesive or atomic layer deposition. The wiring strategy of the flexible wires 8 is crucial to the mechanical reliability of the arm strap. In this embodiment, copper-polyimide composite wires are used, with a thickness of 30 μm and a width of 0.5 mm. To ensure minimal strain on the wires during repeated bending of the arm, the wiring path is precisely designed to be close to the strain-neutral layer of the flexible strip substrate 1. The position of the strain-neutral layer is determined by composite material mechanics theory, calculated using the following formula: ,in , and These represent the Young's modulus, cross-sectional area, and distance to the reference surface for each functional layer.

[0043] These are the Young's modulus, cross-sectional area, and distance from the center of each functional layer (including polyimide substrate, indium tin oxide electrode, organic active layer, encapsulation layer, thermoelectric arm, hydrogel layer, etc.) in the arm band. The strain neutral layer heights of the first and second regions are calculated. Then, a gradient transition layer or serpentine buffer structure is designed at the physical isolation zone to connect the two neutral layers of different heights. Calculations determine that the strain neutral layer of the multilayer structure in this embodiment is located approximately 65 μm from the inner surface of the polyimide substrate. The flexible conductor 8 is arranged in a serpentine pattern along this path and fixed with a small amount of UV-curable adhesive. The dual-source rectifier circuit uses two independent synchronous rectifier architectures to condition the DC power output from the organic photovoltaic power generation unit 3 and the DC power output from the polymer thermoelectric power generation unit 4, respectively, to prevent mutual interference. The maximum power point tracking circuit uses a perturbation observation method to adjust the operating points of the two power generation units in real time, ensuring they always output maximum power. Finally, the electrical energy is stored in the energy storage unit or directly supplied to the load.

[0044] Based on the above-mentioned armband structure, its preparation method is carried out in the following steps in sequence:

[0045] Step S1: Provide a clean, 100 μm thick flexible polyimide strip substrate. Use a laser scribing machine to mark along the length of the flexible polyimide strip substrate, clearly dividing it into a first region and a second region of equal length, ensuring that a 3 mm wide physical isolation strip 2 is maintained between the two regions.

[0046] Step S2: An organic photovoltaic power generation unit 3 is fabricated in the first region on the outer surface of the polyimide flexible strip substrate. First, an indium tin oxide transparent conductive electrode is deposited using a magnetron sputtering device. Subsequently, PTB7-Th:PC is spin-coated using a spin coater in a glove box nitrogen atmosphere. 71 The BM active layer solution was immediately transferred to a hot plate for annealing. Finally, an aluminum back electrode was deposited in a vacuum deposition chamber.

[0047] Step S3 involves high-barrier encapsulation of the organic photovoltaic power generation unit 3 prepared in step S2. The sample is placed in the reaction chamber of an atomic layer deposition (ALD) apparatus, and 25 nm of alumina is deposited at 80 °C using trimethylaluminum and water as precursors. It is then transferred to a chemical vapor deposition (CVD) apparatus, where 2 μm of parylene is deposited at room temperature. This alumina-parylene deposition cycle is repeated twice, and finally, another 25 nm layer of alumina is deposited to complete the five-layer stacked encapsulation.

[0048] Step S4: Prepare polymer thermoelectric power generation unit 4 in the second region on the inner surface of the polyimide flexible strip substrate. Using a 200-mesh screen, alternately print p-type (PEDOT:PSS) and n-type (doped and modified PEDOT:PSS) thermoelectric inks onto the corresponding regions of the polyimide flexible strip substrate to form 10 pairs of parallel strip patterns. Place the sample in an oven and heat-treat at 120°C for 30 minutes. After cooling, use another set of screen templates to print silver paste, and connect the ends of adjacent p-type and n-type thermoelectric arms in series to form a complete power generation circuit.

[0049] Step S5: A skin-friendly thermally conductive interface layer 5 is prepared on the hot end surface of the polymer thermoelectric power generation unit 4. A hydrogel precursor solution of polyvinyl alcohol and glycerol is drop-coated onto the surface of the polymer thermoelectric power generation unit 4, with the thickness controlled by a scraper, and then cured by ultraviolet light irradiation. After curing, an ultraviolet laser etching machine is used to scan the hydrogel layer with a grid pattern with a spacing of 400 μm, etching out a trapezoidal cross-section microstructure channel network with a depth of 15 μm and a width of 100~150 μm. Specifically, an ultraviolet laser with a pulse width of 10~20 ns is used, with a power set to 0.5~1.2W and a scanning speed of 500~800 mm / s. Precise etching to a depth of 15 μm is achieved through multiple repeated scans.

[0050] Step S6: Integrate the cold-end heat dissipation structure 6 on the outer surface of the polyimide flexible strip substrate at a position corresponding to the cold end of the polymer thermoelectric power generation unit 4. Align the porous polyester fabric heat sink pre-coated with low-temperature hot melt adhesive at the position, and use a hot press to hold it at 80 ℃ and 0.2 MPa pressure for 30 seconds to firmly bond it together.

[0051] Step S7: Perform armband circuit integration. First, calculate the position of the strain neutral layer according to the formula, and mark the wiring path with dashed lines on the surface of the polyimide flexible strip substrate. Along this path, apply a small amount of conductive silver paste using a precision dispensing device to adhere and fix the copper-polyimide composite wires. Then, using a micro-spot welder, weld the positive and negative output terminals of the organic photovoltaic power generation unit 3 and the output terminal of the polymer thermoelectric power generation unit 4 to the flexible wires 8, respectively. Finally, connect the other end of the flexible wires 8 to a micro-circuit board (circuit integration module 7) that integrates a dual-source rectifier circuit, a maximum power point tracking circuit, and an energy storage unit, completing the encapsulation and integration of the entire armband.

[0052] Testing showed that the partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband prepared in this embodiment performed well under standard testing conditions (light intensity 100 mW / cm²). 2 At an ambient temperature of 25°C and a skin surface temperature of 33°C, the photoelectric conversion efficiency of the organic photovoltaic power generation unit 3 reaches 12.5%, which is about 16% higher than that of a device with the same structure but without thermal isolation design. The polymer thermoelectric power generation unit 4, when worn, maintains a stable temperature difference of about 6.5°C between its hot and cold ends, achieving an output power density of 15 μW / cm². 2 The skin-conducting thermal interface layer 5 stabilizes the contact thermal resistance at 0.0025 μm. 2 • K / W, fluctuation less than 9%. After 1500 bending cycles with a radius of 15 mm, the resistance change rate of the flexible conductor 8 is only 4.2%. The entire armband works continuously for 24 hours in a simulated sweating environment without performance degradation, and the wearer feels comfortable without stuffiness or itching.

[0053] Example 2

[0054] In medical monitoring scenarios, especially for hospitalized patients or home-based rehabilitation patients requiring long-term, continuous monitoring of vital signs such as ECG and blood oxygen saturation, higher demands are placed on the biocompatibility, long-term wearing comfort, and performance under indoor lighting conditions of energy harvesting devices. This embodiment is based on the core architecture of Embodiment 1, with adaptive optimization of materials and some parameters to better meet the needs of medical-grade applications.

[0055] In this embodiment, the flexible strip substrate 1 is made of polyethylene terephthalate with a thickness of 80 μm, which has higher transparency and better hydrolysis resistance. The length ratio of the first region to the second region is adjusted to 0.9 to accommodate the needs of patients with different arm circumferences, and the width of the physical isolation strip 2 is maintained at 3 mm. The organic active layer of the organic photovoltaic power generation unit 3 adopts a material system that is more sensitive to indoor low light, with PBDB-T as the donor material and ITIC as the acceptor material. The spin-coated film thickness is 180 nm to better utilize the scattered light and illumination light in the ward. The high-barrier encapsulation layer is simplified to a three-layer structure, namely "alumina-parylene-alumina", which reduces the complexity of the process while ensuring sufficient barrier performance, and the water vapor permeability can still be maintained at 5×10⁻⁶. -5 g / (m 2 (day) and below.

[0056] The thermoelectric arm material of polymer thermoelectric power generation unit 4 uses a combination of p-type (PEDOT:PSS, doped with a small amount of ethylene glycol to improve conductivity) and n-type (doped and modified PEDOT:PSS). The thermoelectric arm array adopts a combination configuration of mainly parallel and partially series connection to provide a larger output current under smaller indoor temperature differences, making it more suitable for directly powering low-power sensors. The hydrogel material of the skin-conducting thermal interface layer 5 is replaced with an agarose-polyethylene glycol system, which has better biocompatibility and natural antibacterial properties, with a thickness of 10μm. The microstructure channels are fabricated using a micro-molding process. A polydimethylsiloxane mold is used to imprint the hydrogel precursor before UV curing to form a channel network with a rectangular cross-section, a width of 80μm, a depth of 10μm, and a spacing of 300μm. This process is more efficient and has better consistency.

[0057] The cold-end heat dissipation structure 6 uses a thinner, more breathable medical-grade cotton fiber non-woven fabric heat sink with a porosity of 80% and a thickness of only 1mm. It is bonded with medical-grade pressure-sensitive adhesive for easy replacement and cleaning. In the circuit integration module 7, the maximum power point tracking algorithm uses the incremental conductance method, which offers more stable tracking performance in environments with slow changes in indoor lighting and temperature. The energy storage unit uses a flexible supercapacitor, which has a longer charge-discharge cycle life and is more suitable for frequent, low-current charge-discharge scenarios.

[0058] The preparation method is basically the same as in Example 1. The main differences are: in step S2, the active layer material and spin coating process parameters of the organic photovoltaic power generation unit 3 are adjusted; in step S3, the number of encapsulation layers is reduced; in step S4, the thermoelectric arm interconnection pattern design of the polymer thermoelectric power generation unit 4 is changed; and in step S5, micro-molding is used instead of laser etching to process the microstructure channels of the skin-conducting thermal interface layer 5. In step S6, a medical non-woven fabric heat sink (cold end heat dissipation structure 6) is used instead.

[0059] Under indoor lighting conditions (200 lux) and typical ward temperature differences (skin temperature 33°C, ambient temperature 26°C), the optimized medical version of the organic photovoltaic power generation unit 3 can output approximately 8 μW / cm². 2 The polymer thermoelectric power generation unit 4 can output approximately 5 μW / cm³ of power. 2 The total output power is sufficient to support the continuous operation of a low-power Bluetooth ECG patch. All its materials have passed ISO 10993-1 related cytotoxicity and skin irritation tests. The microstructure channel interface of the skin-conducting thermal interface layer 5 effectively avoids skin maceration caused by sweat retention, significantly improving the comfort and safety of long-term bedridden patients.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any brief modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dual-sided, skin-adhering, sweat-wicking, hybrid energy harvesting armband, characterized in that, include: The flexible strip substrate (1) is divided along its length into a first region and a second region that do not overlap in space; Organic photovoltaic power generation unit (3), which is disposed in the first region on the outer surface of the flexible strip substrate (1); A polymer thermoelectric power generation unit (4) is disposed in the second region of the inner surface of the flexible strip substrate (1); A skin-conducting thermal interface layer (5) is applied to the hot end surface of the polymer thermoelectric power generation unit (4). The skin-conducting thermal interface layer (5) is provided with a preset microstructure channel, which is distributed in a grid or radial pattern that is interconnected. A cold-end heat dissipation structure (6) is disposed on the outer surface of the flexible strip substrate (1) and corresponds to the cold end position of the polymer thermoelectric power generation unit (4); The circuit integration module (7) electrically connects the output of the organic photovoltaic power generation unit (3) and the polymer thermoelectric power generation unit (4) through a flexible wire (8), and the wiring path of the flexible wire (8) is located near the strain neutral layer of the flexible strip substrate (1).

2. The partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband according to claim 1, characterized in that, A physical isolation strip (2) with a width of not less than 2 mm is provided between the first area and the second area, and no functional layer is provided within the physical isolation strip (2).

3. The partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband according to claim 1, characterized in that, The skin-conducting thermal interface layer (5) is composed of a biocompatible ultrathin hydrogel with a thickness of 5 μm to 20 μm; the cross-section of the microstructure channel is rectangular or trapezoidal with a width of 50 μm to 200 μm and a depth of 5 μm to 20 μm, and the depth of the microstructure channel is less than the thickness of the skin-conducting thermal interface layer.

4. The partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband according to claim 1, characterized in that, The polymer thermoelectric power generation unit (4) is composed of an array of multiple p-type thermoelectric arms and n-type thermoelectric arms arranged alternately and connected in series; the material of the p-type thermoelectric arms is poly(3,4-ethylenedioxythiophene): polystyrene sulfonate; the material of the n-type thermoelectric arms is doped and modified poly(3,4-ethylenedioxythiophene): polystyrene sulfonate.

5. The partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband according to claim 1, characterized in that, The organic photovoltaic power generation unit (3) includes a transparent conductive electrode, an organic active layer and a metal back electrode stacked sequentially. The surface of the organic photovoltaic power generation unit (3) is covered with a high-barrier encapsulation layer, which is a 3 to 5 layer stacked structure formed by alternating deposition of Al2O3 and Parylene.

6. The partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband according to claim 1, characterized in that, The cold end heat dissipation structure (6) is a porous fabric heat sink or a thin metal fin array; the porosity of the porous fabric heat sink is greater than 70%; the fin height of the thin metal fin array is 1mm to 3mm.

7. A method for preparing a partitioned, double-sided, skin-adhering, sweat-wicking hybrid energy harvesting armband as described in any one of claims 1-6, characterized in that, Includes the following steps: A flexible strip substrate (1) is provided, and a first region and a second region that do not overlap are divided along its length direction; An organic photovoltaic power generation unit (3) is prepared in the first region on the outer surface of the flexible strip substrate (1) and then encapsulated with high barrier properties. A polymer thermoelectric power generation unit (4) is prepared in the second region on the inner surface of the flexible strip substrate (1). A skin-conducting thermal interface layer (5) with microstructured channels is formed on the hot end surface of the polymer thermoelectric power generation unit (4). A cold end heat dissipation structure (6) is provided on the outer surface of the flexible strip substrate (1) at a position corresponding to the cold end of the polymer thermoelectric power generation unit (4). The flexible wire (8) is wired near the strain neutral layer of the flexible strip substrate (1) and connected to the circuit integration module (7).

8. The preparation method according to claim 7, characterized in that, The steps of preparing the polymer thermoelectric power generation unit (4) in the second region on the inner surface of the flexible strip substrate (1) include: sequentially coating p-type thermoelectric ink and n-type thermoelectric ink by screen printing process, forming an array of alternating p-type thermoelectric arms and n-type thermoelectric arms after patterning and heat treatment, and completing electrical interconnection using conductive paste.

9. The preparation method according to claim 7, characterized in that, The step of forming a skin-conducting thermal interface layer (5) with microstructure channels on the hot end surface of the polymer thermoelectric power generation unit (4) includes: coating an ultra-thin hydrogel precursor, curing it with ultraviolet light, and then processing a microstructure channel with a preset pattern in the cured hydrogel layer using laser etching or molding process.

10. The preparation method according to claim 7, characterized in that, The step of setting a cold end heat dissipation structure (6) on the outer surface of the flexible strip substrate (1) includes: for porous fabric heat sinks, attaching them to the flexible strip substrate (1) by hot pressing process; for thin metal fin arrays, bonding and fixing them by thermally conductive adhesive.

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