Figure 3
From: Miniaturized thermal acoustic gas sensor based on a CMOS microhotplate and MEMS microphone
Numerical analysis. (a) Simplified thermal model illustrating the heat flow from the microheater into the gas and chip due to their thermal capacities \(C_{th}\) and resistance \(R_{th}\) of the chip under DC heating. A temperature rise ΔT occurs on the microheater due to the flow of heat. (b) Experimental vs. numerical calculations showing the relative pressure change in the thermal acoustic cavity with varying volumetric fractions of CO\(_2\), modelled with and without compensation for the photoacoustic effect. (c) Mid-infrared absorption spectrum with 20% CO\(_2\) in air at 0.1 mm absorption length, under standard conditions (296 K, 1 atm).
