Yue Xuejun

High-Performance Humidity Sensors Based on Double-Layer ZnO-TiO2 Nanofibers via Electrospinning

ZnO and TiO2 nanofibers are synthesized via electrospinning methods and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Humidity sensors with double-layer sensing films are fabricated by spinning the ZnO and TiO2 nanofibers on ceramic substrates sequentially. Compared with sensors loading only one type of nanofiber, the double-layer sensors exhibit much better sensing properties. The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 11% to 95% relative humidity, and the response and recovery times are about 11 and 7s, respectively. Maximum hysteresis is around 1.5% RH, and excellent stability is also observed after 180 days. The humidity sensing mechanism is discussed in terms of the sensor structure. The experimental results provide a possible route for the design and fabrication of high performance humidity sensors based on one-dimensional nanomaterials.

High Performance Micro CO Sensors Based on ZnO-SnO2 Composite Nanofibers with Anti-Humidity Characteristics

ZnO-SnO2 composite nanofibers are synthesized via an electrospinning method and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Micro sensors are fabricated by spinning the nanofibers on Si substrates with Pt signal and heater electrodes. The sensors with small areas (600 μm × 200 μm) can detect CO down to 1ppm at 360 °C. The corresponding sensitivity, response time, and recovery time are 3.2, 6s, and 11s, respectively. Importantly, the sensors can operate at high humidity conditions. The sensitivity only decreases to 2.3 when the sensors are exposed to 1 ppm CO at 95% relative humidity. These excellent sensing properties are due to combining the benefits of one-dimensional nanomaterials and the ZnO-SnO2 grain boundary in the nanofibers.