Simplified Approach to Measuring Heater Temperature Oscillations and Phase Lag Inspired by the 3-Omega Technique for Gas Sensing

In this paper, we propose a simplified approach for measuring the heater temperature oscillations and phase lag, inspired by the fundamental principles of the 3-omega technique, intended for use in thermal gas sensing systems. The method enables the extraction of temperature oscillation amplitude and phase lag by directly monitoring the heater's resistance through synchronized voltage and current measurements, thereby eliminating the need for lock-in amplifiers or high-resolution harmonic analysis. By leveraging a series resistor and standard ADCs, the proposed technique significantly reduces system complexity and cost. Experimental validation using a MEMS-based microheater demonstrates that the acquired data are consistent with results obtained via the conventional 3-omega method. The proposed approach is well-suited for integration into low-power, compact, and embedded gas sensing platforms, enabling thermal property-based gas discrimination in wearable or portable devices.