16.1 An ultra-thin flexible CMOS stress sensor demonstrated on an adaptive robotic gripper

Hybrid Systems-in-Foil (HySiF) are becoming important for wearable electronics, medical diagnostics and flexible displays, which require mechanical flexibility or adaptivity as well as large area [1]. Ultra-thin chips are an essential part of HySiF as they allow for analog signal processing or complex digital controllers using well established CMOS technology. However, the effect of mechanical stress on the signal processing circuitry (piezoresistivity) has to be considered during the top-to-bottom design in order to realize stress insensitive analog and digital operation. On the other hand, for sensing mechanical stress on the same substrate, the stress effect needs to be maximized [2], thus leading to conflicting design requirements.