Modeling and simulation of a novel capacitive temperature sensor

A novel capacitive temperature sensor based on multilayer cantilevers is presented. The top and bottom layers are metal and heavily boron doped Si, respectively. A combined SiO₂/Si₃N₄ layer is utilized as the elastic dielectric layers of the sandwich multilayer cantilever. The operation principle of the structure is based on the effect of thermal expansion coefficient mismatch and the available physical effect of strain on the dielectric property. The deformation of the cantilever due to temperature is sensed and translated to an electrical capacitance change. After the structures of this sensor were designed, the mechanical characteristics of the sensor are theoretically analyzed with the extension of two-layer Timoshenko model. Calculation shows that, compared with traditional temperature sensors, the proposed structure may have a wider temperature range from -90°C to 90°C. This makes it suitable to act as air temperature sensor in radiosonde.