Catalytic Hafnium Oxide Calorimetric MEMS Gas and Chemical Sensor

Abstract

In this paper we introduce the design and fabrication of a MEMS-based calorimetric sensor platform with a focus on both gas and vapor phase detection of volatile compounds. An ALD-grown hafnium oxide thin film was integrated and used as a catalyst to enhance the oxidation of the detected analytes and hence increase sensitivity, selectivity and lower the detection limit of the sensor. ALD enabled the atomically-precise design of the hafnium oxide catalyst, which allows for lower detection limits without the need for polymeric pre-concentrators. The sensing principle was theoretically studied using the Finite Element Method (FEM), which has verified the possibility of using this platform for continuous detection and obtaining a unique detection signal at different temperatures. Experimental testing of the platform further verified its usability for oxidation detection of methanol vapor with less than 5 seconds adsorption time. Experiments obtained a unique signal at different heater temperatures which could be increased more than 23 times by increasing the heater voltage from 3.5 to 5.0 V. Selectivity versus acetone vapor was also experimentally verified.