Electro-Thermal Simulation & Characterization of a Microheater for SMO Gas Sensors

The microheater is an important part of a semiconducting metal oxide gas sensor, as its primary function is to heat up the sensitive layer to a desired temperature. The operating temperature of the sensor depends on the sensitive material used and the species of the target gases. Therefore, an accurate extraction of the sensor active area temperature as a function of the applied power is critical for device characterization. These measurements are experimentally challenging due to the extremely small sensing surface area, down to a few tens of μm
²
, resulting in the need to develop new measurement approaches. In this paper, quantitative testing methods based on platinum and chrome silicon (CrSi) resistance thermometry, as well as a qualitative testing method (light glow) have been carried out to measure the power consumption of two different devices. CrSi has been used as a temperature sensor due to its ability to detect temperatures above 450 °C by acting as a phase-change material. For accurate measurements of temperature distribution, the presented gas sensors are equipped with three configurations of resistive temperature detectors at different locations. To further analyze a sample closed-membrane sensor, finite-element simulations were performed and an analytical model was designed and compared with experimentals.