Piezo-Resistance (PZR) for PZR Sensors
PZR Sensor Simulation Made Easy
Many solid-state sensors for mechanical signals are based on the piezoresistive effect, where a change in the resistivity of a piezoresistive material subject to a mechanical stress is used to measure physical quantities such as pressure, force, and acceleration
CoventorWare provides a unique approach for simulating piezoresistive (PZR) sensors, taking advantage of the dominance of the piezoresistive effect over shape change on sensor output. The stress field is precomputed using CoventorWare’s mechanical solver and mapped onto the geometry of the piezo sensor. This method allows for a more efficient mesh and for later updates to the position and orientation of the piezo sensor within the stress field without needing to re-mesh or perform the simulation again.
CoventorWare’s MemPZR module then employs the pre-computed stress field with user-specified electrical and piezoresistive coefficients to compute the electric field (and the resulting changes in current) as they are affected by pressure and temperature. Uniquely 2nd order piezoresistive coefficients can be included, to capture non-linear piezoresistive behavior that is significant in certain classes of pressure sensor.
The graphic shows diaphragm deformation under applied pressure, with a plot of the stressYY field and a brick mesh mapped on the diaphragm. For clarity, highly doped tracks and thin film passivation layers are not shown in the graphic (these can be included, if needed).