Modeling and simulation of infrared sensors using cantilever and bridge structures

Thermopiles have several advantages for working as infrared sensors and have already been used for applications in environmental monitoring and biomedical diagnostics. When designing thermopiles, it is of great importance to acknowledge the changes in the output voltage that the varying of each design variable may generate. In this work, the model of a thermopile with a bridge or cantilever structure that includes the thermocouples thickness, width and thermal conductivity, parameters not taken into account before, is developed. Choosing the thermocouples length for a thermopile with a fixed length membrane is not trivial. For the simulated structure with a membrane length of 900 nm, when varying the length of the thermocouples from 28 to 72% the length of the membrane, a difference in the output voltage of 81 μV was observed. A comparison between bridge and cantilever structures shows that the former achieves sensitivities up to 1.8 times the ones obtained with cantilever structures.