Haoxuan He

High Piezo-photocatalytic Efficiency of CuS/ZnO Nanowires Using Both Solar and Mechanical Energy for Degrading Organic Dye

High piezo-photocatalytic efficiency of degrading organic pollutants has been realized from CuS/ZnO nanowires using both solar and mechanical energy. CuS/ZnO heterostructured nanowire arrays are compactly/vertically aligned on stainless steel mesh by a simple two-step wet-chemical method. The mesh-supported nanocomposites can facilitate an efficient light harvesting due to the large surface area and can also be easily removed from the treated solution. Under both solar and ultrasonic irradiation, CuS/ZnO nanowires can rapidly degrade methylene blue (MB) in aqueous solution, and the recyclability is investigated. In this process, the ultrasonic assistance can greatly enhance the photocatalytic activity. Such a performance can be attributed to the coupling of the built-in electric field of heterostructures and the piezoelectric field of ZnO nanowires. The built-in electric field of the heterostructure can effectively separate the photogenerated electrons/holes and facilitate the carrier transportation. The CuS component can improve the visible light utilization. The piezoelectric field created by ZnO nanowires can further separate the photogenerated electrons/holes through driving them to migrate along opposite directions. The present results demonstrate a new water-pollution solution in green technologies for the environmental remediation at the industrial level.

Self-powered, stretchable, fiber-based electronic-skin for actively detecting human motion and environmental atmosphere based on a triboelectrification/gas-sensing coupling effect

A new self-powered, stretchable, fiber-based electronic-skin (e-skin) has been fabricated for actively detecting human motion and environmental atmosphere. Several bundles of carbon fibers (coated with polydimethylsiloxane (PDMS) or polypyrrole (Ppy)) were woven together, forming a flexible fiber-based e-skin. The triboelectric current of the e-skin was dependent on the strain deformation and the environmental atmosphere. The e-skin can actively detect various human motions, such as finger touch, joint motion, skin deformation and slight stretching. Each PDMS–Ppy crossing point can be employed as an independent unit, and these units can output triboelectric current individually, realizing the tactile perception. The e-skin can also monitor volatile organic compounds in the atmosphere with high sensitivity, recovery and selectivity, (e.g. upon exposure to 1200 ppm methanol vapor, the triboelectric current of the e-skin decreased from 41.17 (in air) to 15.12 nA). The working mechanism is based on the triboelectrification/gas-sensing coupling effect. This new device architecture and material system can promote the development of a self-powered multifunctional e-skin.

A Self-Powered Wearable Noninvasive Electronic-Skin for Perspiration Analysis Based on Piezo-Biosensing Unit Matrix of Enzyme/ZnO Nanoarrays

The emerging multifunctional flexible electronic-skin for establishing body-electric interaction can enable real-time monitoring of personal health status as a new personalized medicine technique. A key difficulty in the device design is the flexible power supply. Here a self-powered wearable noninvasive electronic-skin for perspiration analysis has been realized on the basis of a piezo-biosensing unit matrix of enzyme/ZnO nanoarrays. The electronic-skin can detect lactate, glucose, uric acid, and urea in the perspiration, and no outside electrical power supply or battery is used in the biosensing process. The piezoelectric impulse of the piezo-biosensing units serves as the power supply and the data biosensor. The working mechanism can be ascribed to the piezoelectric-enzymatic-reaction coupling effect of enzyme/ZnO nanowires. The electronic-skin can real-time/continuously monitor the physiological state of a runner through analyzing the perspiration on his skin. This approach can promote the development of a new-type of body electric and self-powered biosensing electronic-skin.

A self-powered electronic-skin for real-time perspiration analysis and application in motion state monitoring

A new self-powered electronic-skin (e-skin) for real-time perspiration analysis has been fabricated from a polyaniline (PANI) triboelectric-biosensing unit matrix, which can also work as a self-powered visualization system for preventing exercise injury (dehydration). The biosensing units on the e-skin can be driven by body motion through efficiently converting mechanical energy into triboelectric current. After surface modification with enzymes and a drop-cast chitosan film, the triboelectric output of the biosensing units can be influenced by the target biomarkers, acting as a biosensing signal. This new triboelectrification/enzymatic-reaction coupling effect has been demonstrated in different biosensing units that can detect the urea, uric acid, lactate, glucose, Na+ and K+ concentration in perspiration without any external electricity power. The e-skin can be linked to a visualization panel, and the input triboelectric current can show the motion state of the human body during exercise. This work can provoke a new research direction for developing wearable healthcare diagnosis systems and self-powered visualization systems. This new technique could also reduce medical expenses and facilitate application in low-income regions.