Design and Simulation of 3D ZnO Nanowire Based Gas Sensors for Conductivity Studies

N. Gouthami, D. Parthiban, M. Alagappan, and G. Anju
PSG College of Technology
Tamil Nadu, India

The objective of this paper is to design a 3D Gas Sensor for sensing Hydrogen gas and to increase the conductivity at nano level. In this novel design, nanorods act as the sensing layer. The sensitivity towards gas adsorption is found to be increased due to its high surface to volume ratio. The total displacement and voltage on intermediate layer after gas adsorption will be changing by varying its thickness.

In this paper, COMSOL Multiphysics 4.1 is used for modeling and simulation. The substrate selected in this model is Lithium Niobate (LiNbO3), due to its high electromechanical coupling coefficient, whereas Zinc Oxide is used for both intermediate layer and sensing layer with aluminum as the metalized IDTs. MEMS module was used by including piezoelectric devices and solid mechanics as the physics.

By varying the thickness of the intermediate layer (ZnO), there is an increase in the total displacement, higher sensitivity and mechanical robustness because it prevents energy loss into the bulk of substrate. The conductivity is found to be increasing till a certain value of the intermediate thickness after which it started decreasing. Hence the intermediate layer thickness has to be optimized to obtain suitable conductivity. Also the use of ZnO nanorods on the sensing layer enhances the conductivity. Thus this sensor will be acting as better devices for sensing the amount of hydrogen gas in the atmosphere.