What are MEMS?
MEMS (Micro Electro Mechanical Systems) are the integration of electrical devices and mechanical structures at the micrometer (10-6 m = 0.000001 m) scale. The essence of MEMS is their ability to perform and enhance tasks, in ways and in the micro world, impossible using conventional technologies. MEMS devices find applications in the automotive, medical, aerospace,defense and telecommunications industries. Although, electrical devices and very few mechanical devices at this scale are common, the scaling down of common mechanical devices found in the macro world has created a research area all its own. The behavior of mechanical structures at the microscale has yet to reach full understanding.
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Figure1. TRW prototyped digital propulsion Microthruster. This microthruster contains 15 individual thrusters in the central 3x5 array.
(Photo Cortesty of TRW)
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Figure 2. EmKay Sisonic Microphone,.This microphone is made from Silicon and is only millimeters large.
(Photo Courtesy of EmKay)
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Althouhgh, MEMS are created using many of the fully understood processing techniques used in IC ( Inetegrated Circuit) processing with little variation, there are still many material, fabrication and packaging issues that have yet to be resolved. The semiconductor industry already has much of the infrastructure to batch process MEMS devices, however, the expertise to mass produce a wide variety of MEMS devices is still in its infancy, stimulated by research funded by both corporations and government agencies.
Types of MEMS Devices:
MEMS devices can be classified in many ways, however in the broader sense there are only two types, sensors and actuators. Some devices act as both sensor and actuator. The remaining systems include individual types or combinations with added electronic circuitry for control and/or processing information. The three basic types of MEMS devices are:
1. Sensor - converts a nonelectrical input quantity (i..e. pressure, temperature, acceleration) into an electrical ouput quantity. Sensors are commonly encountered.
2. Actuator - converts electrical input quantities into non-electrical ouput quantities.
3. Smart MEMS - MEMS combined with additional electronic circuitry for control and processing information
Role of MEMS in Space Applications:
NASA has a very special interest in MEMS technology. MEMS offer the benefits of significantly reduced mass and power consumption translating directly into direct cost benefits as a result of the major decrease in size. Some of the systems utilizing MEMS devices for space applications are:
- Microthrusters
- Mass Spectrometers
- Magnetometers
- RF Switches
- Microgyroscopes
The main obstacle in rapidly integrating new technologies into space systems is determining system reliability. Reliability, the ability of a device/system to maintain performance requirements throuhgout its lifetime, is a major consideration factor for making device selections for space flight applications. Space missions can be expected to last upwards of 5 years with spacecraft subject to extreme mechanical shock, vibration, temperature, vacuum, and radiation environments.
NEPP and MEMS:
NEPP's task is to characterize new and emerging technologies that could provide substantial performance and/or cost benefits for future NASA missions.
NEPP will attempt to ease the integration process (MEMS into space flight systems) by identifying and addressing reliability issues in the early stages of MEMS development which will result in major direct cost benefits to current and future NASA Projects.
Information Provided by Muzar A. Jah
Code 562
Last Updated: May 12, 2003
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