Gas and Chemical Sensors

 

Related research topics in our group:

  • Electronic Nanomaterials

  • Electronic Devices

  • Stretchable and Healable Electronics

  • Analytical Microsystems and CMOS Circuits

The “Sensor Revolution”, in conjunction with “Internet-of-Things”, carries the vision of analyzing and defining the environment by a ubiquitous deployment of smart, autonomous, and inexpensive sensors. Beyond traditional measurement such as temperature and humidity, emerging sensors are expected to monitor complex phenomena, for example, water quality, gas toxicity, and microbiological growth. Since chemical, bio, and environmental sensors typically measure targets that have many constituents and in the presence of a complex background, it is challenging to design sensors that are accurate, selective, and robust against disturbance. In addition, many sensors exhibit hysteresis and environmental degradation, requiring frequent calibration. 

 

Our group investigates various techniques to tackle the open challenges. For example, we have prepared 2D materials such as liquid-phase exfoliated black phosphorus (BP) nanosheets for nitrogen dioxide (NO2) sensing. The unique combination of probe sonication and ice-water bath sonication is capable of producing BP nanosheets of various controllable sizes. In another work, we explore morphology evolution of MoS2 nanostructures and the resulting room-temperature gas sensing performance tradeoffs.

We also pay careful attention on the sensor electrode. Existing gas sensors using conventional electrodes involve complex fabrication processes, resulting in high cost, thus severely limiting their ubiquitous application. We design, fabricate, and characterize MoS2 gas sensors utilizing laser-induced graphene (LIG) electrodes. Overall, high performance in gas sensing combined with low susceptibility to mechanical damage enables the sensor to serve a variety of wearable sensory applications.

Selected publications:

W Yan, T Chen, J Xu, Q Tian, and D Ho, "Size-Tunable flowerlike MoS2 nanospheres combined with laser-induced graphene electrodes for NO2 sensing," ACS Applied Nano Materials, 3, 3, 2020.

K W Cheung, D Kuo, J Yu, and D Ho*, "A Novel Method for Predicting Optimal Gas Sensing Temperature of Morphologically Distinct Nanostructured Schottky Interfaces," Sensors and Actuator B - Chemical, 287, 2019.

J Yu, W Yan, K W Cheung, Y Li, and D Ho*, "High-Sensitivity Low-Power Tungsten Doped Niobium Oxide Nanorods Sensor for Nitrogen Dioxide Air Pollution Monitoring," Sensors & Actuators: B - Chemical, 238, 2016.