Design of piezoresistive-based MEMS sensor systems for precision microsystems

Piezoresistive sensing systems have characteristics that enable them to act as fine-resolution, high-speed force and displacement sensors within MEMS and other small-scale systems. High-performance piezoresistive sensing systems are often difficult to design due to tradeoffs between performance requirements, e.g. range, resolution, power, bandwidth, and footprint. Given the complexity of the tradeoffs, traditional approaches to system design have primarily focused upon optimizing a few, rather than all, elements of the sensing system. This approach leads to designs that underperform the sensors optimized range and resolution by as much as two orders of magnitude. In this paper, we present a general systems approach that enables rapid optimization of all elements via a model that incorporates the behavior, noise and sensitivity associated with each element of the sensing system. The model is presented in a manner that makes the underlying principles and application accessible to a broad community of designers. The utility of the model is demonstrated via an example wherein design parameters are altered to maximize dynamic range.