• Aimil Limited

Shock Accelerometers, Subminiature

Meggitt Sensing Systems, a Meggitt group division, has introduced the Endevco® model 71M series, a family of rugged, undamped subminiature surface mountable piezoresistive accelerometers, designed to support a variety of high-g shock measurement requirements. With available g ranges of 2K, 6K, 20K and 60K, design of the Endevco model 71M series features a patented, monolithic, four-active arm bridge circuit design (US patent numbers 4,498, 229, 4,605,919 and 4,689,600) incorporating the use of Meggitt’s own proprietary sensing element, machined in-house from a single piece of silicon at its ISO9001 certified MEMS facility in Sunnyvale, California, USA. This etched silicon chip includes both the inertial mass and strain gages arranged in an active four-arm Wheatstone bridge circuit, complete with a novel on-chip zero balance network. The element is housed within a low-profile, miniature, epoxy sealed subminiature surface mountable package, weighing just 0.06 gram, for minimized mass loading effects. The low mass, small size and unique construction of the MEMS sensing element allows for high resonance frequency, low output impedance, 3x over-range, and zero damping for minimal phase shift over its useful frequency range. The high resonance frequency of the Endevco® 71M series permits their survival in the presence of high-frequency components, in a shock pulse that could otherwise shatter the seismic system of accelerometers having lower resonance frequencies. Because they are undamped, the accelerometers can also accurately respond to fast rise times and short duration shock motion. With a frequency response extending down to dc (steady state), they are ideal for measuring long duration transient shocks while integrating critical acceleration data for velocity and displacement.