| At present,traditional medical monitoring has problems such as poor accessibility,bulky equipment,high cost,uncomfortable experience and dependence on external power supply.The Triboelectrification nanogenerator(TENG)is an innovative technology to solve the power supply problem of equipment.Based on the coupling effect of triboelectrification and electrostatic induction,TENG collects mechanical energy from surrounding mechanical activities and converts it into electrical energy,providing continuous power for most microelectronic devices.TENG has brought many changes to the field of medical monitoring due to its low cost,simple construction,ease of manufacture and variety of material choices.However,most of the materials used in the preparation of TENG are synthetic polymers and metals,which are not easily treated and degraded,and their discarding and accumulation pose potential threats to human health and the environment,and do not meet current national resource utilization requirements.Waste papers material is a kind of green and environmental protection material,which contains abundant cellulose and is a potential candidate material.Cellulose nanocrystal(CNC)is cellulose derivatives that can be used as reinforcement to fill other polymers.A composite film with high transparency,good flexibility,good electrification performance and good biodegradability was obtained by adding nano-packing CNC into the methylcellulose(MC)film.The composite film can be dissolved in deionized water quickly at room temperature.The water-soluble CNC/MC film is an ideal material for the preparation of wearable TENG.In this work,we first presented a fully water-soluble TENG(WS-TENG)based on waste printer paper.This low-cost,lightweight,biodegradable and fully water-soluble WS-TENG is used as a disposable bandage sensor for real-time monitoring of human respiratory and physiological signals.When the job is done,the entire unit can be washed with water without environmental concerns.The main research contents are as follows:(1)Using waste paper base as cellulose source,CNC nanomaterials with needle-like structure were prepared by mixed treatment of strong alkali solution and sulfuric acid hydrolysis.CNC was added to MC film as nano filler to form a CNC/MC composite film with higher electrification than the metal friction layer.CNC/MC films are water-soluble and degradable in the natural environment.The content of CNC and MC determines the tribological electrification performance of CNC/MC film,and the content of MC determines the mechanical properties of CNC/MC film.CNC/MC films containing 0.072 g and 0.075 g respectively have the best performance.When the contact area is 2 cm×2 cm,the open-circuit voltage,transfer charge density and short-circuit current can reach 205 V,180?C/m~2and 18?A,respectively.(2)A completely water-soluble WS-TENG was prepared and used for monitoring human respiratory signals and other physiological signals,in which CNC/MC was used as the positive friction layer material,MC as the negative friction layer material,and self-made graphite conductive tape as the conductive electrode.The sensor can accurately distinguish various breathing states(light,normal,deep,fast breathing)as the output voltage changes between 0 and 2 V,and can be used as a bandage sensor in the field of medical monitoring.Unlike conventional equipment,WS-TENG is self-powered and can be washed directly with deionized water after use without the high cost of recycling.WS-TENG also showed good sensitivity when used for monitoring other joints. |
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