TRANSACTION ON CONTROL AND MECHANICAL SYSTEMS, VOL. 1, NO. 6, PP . 239-244, OCT., 2012. RECEIVED: 16, JUL., 2012; REVISED: 1, OCT., 2012; ACCEPTED: 4, OCT., 2012; PUBLISHED: 25, OCT., 2012. Abstract: Recent advances in microelectromechanical systems (MEMS) technology have resulted in MEMS gyroscopes that are lighter and smaller, consume less power, and are lower in cost compared to spinning disk or wheel type mechanical gyroscopes. MEMS devices have permitted the use of gyroscopes in a wide variety of applications in the consumer, industrial, automotive and avionics markets. These applications cover a wide range of environmental conditions ranging from mild to harsh, with harsh environments often including exposure to high temperature and high humidity. Characterization of the behavior of the MEMS gyroscope in such harsh environments is an essential element in ensuring their reliable use. This article demonstrates the effects of exposure to elevated temperature and sustained exposure to temperature- humidity on the performance of a MEMS vibratory gyroscope. Keywords: MEMS Gyroscope, Inertial Sensors, Reliability, Harsh Environment. 1. INTRODUCTION The unique features of MEMS inertial sensors, (viz. accelerometers and gyroscopes) compared to macro-scale devices have recently made them very popular for a wide variety of applications, causing the market for MEMS inertial sensors to grow rapidly each year. Yole development has projected that the inertial sensors market will grow from $3.2B in 2011 to $4.8B in 2016 as shown in Fig. 1 [1] . MEMS inertial sensors are included in many applications in the consumer market, such as image stabilization in digital cameras and camcorders, remote control in virtual gaming devices, and motion sensing in next-generation mobile phones and tablets. Other markets also include automotive, medical, aerospace, defense and robotics. Each of these markets demands specific characteristics of the MEMS inertial sensors. For example, military and avionics markets require sensors with broad measurement bands and high resolution, while consumer applications require only a low-cost sensor to measure an orientation change. Recently, MEMS inertial sensors have been This work was supported by Maryland Industrial Partnership Program, TRX Systems, Inc. and CALCE (Center for Advanced Life Cycle Engineering) at University of Maryland, College Park. 1 Chandradip Patel is a PhD candidate at CALCE, Mechanical Eng. Dept. University of Maryland, College Park, USA (cpatel@umd.edu) 2 Patrick McCluskey () is an Associate Professor at CALCE, Mechanical Eng. Dept., University of Maryland, College Park. USA (mcclupa@umd.edu). incorporated into a series of inertial navigation units, typically consisting of an accelerometer, a gyroscope, and a compass (magnetometer), where high sensitivity and stable performance against environmental fluctuation are key requirements. Fig. 1: MEMS Inertial Market Trend [1] Since the largest markets for MEMS gyroscopes are in consumer and industrial electronics, most commercial-off-the-shelf (COTS) MEMS gyroscopes are designed to operate over a limited temperature range. Typically, this operating temperature range varies from -40˚C to +85˚C, although, recently, it has been extended to +105˚C in some devices. This operating range can limit use in some applications, such as navigation and tracking, deep well energy exploration, and down-hole drilling, where the MEMS gyroscope sensor experiences temperatures that are beyond the manufacturer’s recommended temperature range. Characterization of MEMS gyroscope behavior in such environments is an essential part of determining if the devices can be used over a wider temperature range. The performance and reliability of MEMS gyroscopes can be affected by a wide range of harsh environmental conditions including high temperature, high humidity, high-G mechanical shock/drop, high mechanical vibration and high frequency acoustic noise. The effects of high-G mechanical shock/drop [2–4] , high levels of mechanical vibration [5-6] and high frequency acoustic noise [7-8] already have been well investigated. This study focuses on the effects of elevated temperature and sustained exposure to temperature combined with humidity on the performance of MEMS vibratory gyroscopes. 2. ELEVATED TEMPERATURE ENVIRONMENT Temperature-dependent material and electrical properties significantly affect the output of MEMS gyroscopes used over a wide temperature range. A series of experiments were conducted on MEMS vibratory A Characterization of the Performance of MEMS Vibratory Gyroscope in Temperature and Humidity Environments Chandradip Patel 1 and Patrick McCluskey 2,