Large Area Flexible Triaxial Force Sensor Array

This paper is focused on the multiphysics 3-dimensional Finite Element Method (FEM) numerical simulation of the capacitive electro-mechanical behavior of an innovative large area flexible triaxial force sensor array, fabricated through standard micromachining, together with its mechanical experimental validation. Fabrication induced residual stress is considered and pressure and shear load conditions are simulated.The presented model properly captures the initial deformation due to the residual stress and it correctly simulates the contact between the suspended butterfly layered plate and the substrate.The numerical model provides the design guidelines and predicts the sensor performance of a unit 1 $\mathrm{cm}^{2}$ footprint 29 x29 array. In particular, it is characterized by an initial capacitance $C_{0}$ of 640 pF, while the pressure sensitivity is 1.920 pF/kPa at p=175kPa and the shear sensitivity is 1.6 pF/kPa at $\tau_{X}=$100kPa.The reported pressure and shear sensitivities are respectively at least 11 and 23 times greater than state of the art flexible sensors [3] based non-standard fabrication process.Hence, the presented technology represents a solution for highly sensitive large area flexible triaxial force sensors with batch manufacturability.