The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

Abstract

This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition method. Sensor performance at a fixed operating temperature of 330 °C for the different film deposition methods was evaluated by exposure to 500 ppm of the target gas carbon monoxide. A consequence of the poor film structure, large variability and poor signal properties were observed with the sensors fabricated using binders. Specifically, the sensors created using the binder recipes yielded sensor responses that varied widely (e.g., S = 5 – 20), often with hysteresis in the sensor signal. Repeatable and high quality performance was observed for the sensors prepared using the binder-less dispersion-drop method with good sensor response upon exposure to 500 ppm CO (S = 4.0) at an operating temperature of 330 °C, low standard deviation to the sensor response (±0.35) and no signal hysteresis.

Analysis of Unusual and Instantaneous Overshoot of Response Transients in Gas Sensors

“…The binding of reducing gas results in increase of charge carriers, which is reflected in conductance and vice versa for an oxidizing gas. However, seldom an overshoot is encountered in the response transients of the oxide gas sensors, which is most likely overlooked by the researchers . This unusual and instantaneous overshoot carries a crucial information about the interaction of gas with the Metal Oxide (MO) surface .…”

“…However, seldom an overshoot is encountered in the response transients of the oxide gas sensors, which is most likely overlooked by the researchers . This unusual and instantaneous overshoot carries a crucial information about the interaction of gas with the Metal Oxide (MO) surface . Nonetheless, the nature and extent of this surface reaction is found to vary with size, shape and most importantly the crystalline surface (facets) of the oxides …”

“…[14][15][16][17] This unusual and instantaneous overshoot carries a crucial information about the interaction of gas with the Metal Oxide (MO) surface. [15,17,18] Nonetheless, the nature and extent of this surface reaction is found to vary with size, shape and most importantly the crystalline surface (facets) of the oxides. [19][20][21][22][23][24][25] Here, we investigate the origin of such unusual overshoot encountered during exposure of ZnO microrods to Hydrogen gas at high temperatures.…”

NAP-XPS Study of Ethanol Adsorption on TiO2 Surfaces and Its Impact on Microwave-Based Gas Sensors Response

“…In this case, the sensor response exhibits a slight overshoot which is usually attributed to secondary reactions or diffusion-reaction phenomena [5]. However, the amplitude of this overshoot is reduced by multiplying the number of concentration pulses.…”

Synthesis of Tin Oxide Thick Film and Its Investigation as a LPG Sensor at Room Temperature

“…The gas sensing properties of SnO 2 semiconductor thick film have been found to depend strongly on the method of processing [21,22]. Among the structural parameters, the crystallite size has prominent effect on the gas sensitivity.…”