Robust control and failure assessment of MEMS employed in physically demanding, mission critical applications will allow for higher degrees of quality assurance in MEMS operation. Device fault detection and closed-loop control require detailed knowledge of the operational states of MEMS over the lifetime of the device, obtained by a means decoupled from the system. Preliminary through-wafer optical monitoring research efforts have shown that through-wafer optical probing is suitable for characterizing and monitoring the behavior of MEMS, and can be implemented in an integrated optical monitoring package for continuous in-situ device monitoring. This presentation will discuss research undertaken to establish integrated optical device metrology for closed-loop control of a MUMPS fabricated lateral harmonic oscillator. Successful linear closed-loop control results using a through-wafer optical microprobe position feedback signal will be presented. A theoretical optical output field intensity study of grating structures, fabricated on the shuttle of the resonator, was performed to improve the position resolution of the optical microprobe position signal. Throughwafer microprobe signals providing a positional resolution of 2 m using grating structures will be shown, along with initial binary Fresnel diffractive optical microelement design layout, process development, and testing results. Progress in the design, fabrication, and test of integrated optical elements for multiple microprobe signal delivery and recovery will be discussed, as well as simulation of device system model parameter changes for failure assessment.

As microelectromechanical systems (MEMS) devices migrate into progressively more critical systems, the reliability these devices have to demonstrate must increasingly improve. Current research in the reliability of MEMS has succeeded in increasing the reliability of commercialized MEMS before they are integrated into an application by focusing on fabrication processes, device materials, and packaging. In this study, the focus is on assessing the reliability of MEMS during device operation. A fault detection approach was taken to diagnose incipient changes in the operation of MEMS devices. Model-based fault detection schemes utilizing the Kalman filter and H ∞ filter as residual generators were investigated. Analysis of the residual was conducted using a discrete Fourier transform (DFT). Two common MEMS research devices, the lateral comb resonator and parallel plate actuator, are used to demonstrate theoretically and experimentally the ability of the fault detectors to identify induced faults in linear and nonlinear domains of system operation. v 3.3.1 Extended Kalman Filter Results .