Shankar Chandrasekaran

A Hybrid MEMS–Fiber Optic Tunable Fabry–Perot Filter

This paper describes a bulk-micromachined electrostatically tunable Fabry-Perot interferometric filter. The device is a hybrid optical filter combining fiber optics and microelectromechanical systems (MEMS) technologies. The static mirror is a Bragg grating mirror built on the end face of an optical fiber that is integrated with a MEMS device, which includes the tunable gold-coated mirror. The MEMS device is fabricated in ¿100¿-oriented silicon wafers using modified and optimized batch MEMS processes. A two-stage approach was used to achieve high finesse (F) and broad tunability simultaneously. In the first stage, actuator issues and mirror structural defects were corrected for by optimizing the fabrication-process parameters. In this stage, near-theoretical performance has been achieved with a pure Si MEMS tunable etalon. In stage two, optical fibers with dielectric stack mirrors from Micron Optics, Inc. have been integrated with the MEMS devices to form tunable cavities. The device insertion loss was below 15 dB and was mostly attributed to absorption losses in the gold coating. We measured a pass bandwidth of around 0.54 nm and a tuning range of nearly 120 nm resulting in an F of over 220.

Probabilistic Analysis of a Comb-Drive Actuator

In the present paper, we discuss about design methodology to study the reliability of a microelectromechanical systems device. The proposed methodology was illustrated for design of a comb-drive actuator. In particular, effect of variations introduced in the design parameters due to the fabrication process and their impact on reliability of a comb-drive actuator is reviewed in detail. We use Crystal Ball® (Decisioneering, Inc., 2000), a probabilistic analysis tool to analyze the performance of comb-drive actuator. The present method requires an analytical model or transfer function derived using experimental data to study the variation in output due to variations in input parameters. We developed an analytical model for displacement of actuator and verified the analytical model using finite element model. This analytical model was used to study the variation in displacement of comb-drive actuator. This methodology uses a combination detailed experimental studies done to establish fabrication limitations or capabilities. The analysis and final design selection was based on a combination of Crystal Ball® studies and fabrication constraints. The same methodology could be extended to study the reliability of MEMS sensors and actuators due to variations on process parameters.

An approach for the study of reliability for a MEMS magnetic actuator

This paper presents a summary of the design for reliability and the reliability test procedures used for the design, fabrication and testing of a MEMS magnetic actuator. The MEMS device reliability is determined incorporating device structure, its fabrication process, the packaging, & their interacting contributions. The goal of the MEMS actuator reliability design task is to increase the probability of failure free operation of a MEMS based system for a specified time period and the use environment. The design for reliability and the subsequent reliability testing procedures are used to determine the reliability of the MEMS actuator and enable the determination of the reliability of the final product that the MEMS device is becoming part of.