Design and electro-thermo-mechanical analysis of high temperature molybdenum microheaters for exhaust gas sensing applications

Microheaters play a vital role in gas sensor applications. Exhaust gas sensors need high temperature microheaters to heat sensing films uniformly at low powers. In this paper, we present design and electro-thermo-mechanical analysis of molybdenum microheaters suitable for high temperature exhaust gas sensors. Double-spiral (DS), double-meander (DM), cross-meander (CS), modified-S (MS) and modified double spiral (MDS) shape structures were considered for simulation. The geometry of the resistive structure was optimized to improve temperature uniformity over a heating area of 500 × 500 μm². Simulations show that the microheater consumed 83.65 mW power to reach a maximum temperature of 800 °C with a temperature gradient of 8.2°C. Structural deformation of the microheater membrane was studied to determine its stability and reliability under high thermal stresses. The maximum membrane deformation was found to be 15.25 μm at 800°C. Platinum, tungsten and molybdenum microheaters were compared in terms of their power consumption, temperature gradient and membrane deformations.