Extraction of compensated σxx-σyy and σxy stresses from a single four-contact sensor using the spinning transverse voltage method

This paper reports on a novel method for extracting two stress components separated from undesired signal contributions with a single four contact piezoresistive structure. To date, such results were obtained only using two separate four contact structures, e.g., Wheatstone bridges of piezoresistors and piezoFETs, or using structures with a larger number of contacts. The method proceeds by spinning the current in the device, similarly to the spinning current method for Hall devices. It features the capability of (i) extracting both σ_xx-σ_yy and σ_xy stresses, (ii) separating the stress dependent signals from other undesired signals, such as Hall voltages, thermoelectric voltages, and temperature dependent effects, and (iii) a straightforward integration into mixed signal systems without the necessity of any compensation of offsets due to the amplifier and A/D conversion stage. Further, the approach is even applicable to nonlinear devices.