Monday, 4 May 2015

Uniaxial MEMS piezoresistive accelerometer

Patent filing no.: 737/KOL/2013

Technology title: Uniaxial MEMS piezoresistive accelerometer with enhanced cross-axis signal reduction

1.    A brief description of the technology
MEMS accelerometers are micromechanical inertial sensors used for aerospace, civil, automotive, industry and consumer electronics applications. Uniaxial MEMS piezoresistive accelerometers are primarily used in strategic domains such as navigation and guidance of aircrafts and ballistic missiles. Our technology involves the conceptualization of a single-axis MEMS piezoresistive accelerometer variant designed for inertial navigation systems with enhanced crosstalk (signals along axes other than the primary sensing axis) rejection. Crosstalk is a significant aberration in accelerometer output and can severely interfere with precise definition of position and orientation which can result in catastrophic disasters. The technology is aimed at creating a system which can operate efficiently within an inertial measurement unit.
2.    Commercial prospect of the technology
Accelerometers are indispensable in applications involving motion, ranging from kinesiological studies to motion guidance in ballistic systems. It is expected that important industrial sectors such as automotive, aerospace, and strategic should benefit from such a technology, not to mention the increasing applications of MEMS inertial sensors in the field of consumer electronic gadgets.
3.    Advantages of this technology over the already existing methods
Highly precise uniaxial sensing with robust linearity, appreciable sensitivity due to the mechanical design layout and added flexibility of electrical design layout on either wafer surface. Extremely low-noise and ~1000g shock survivability under packaged conditions provide further value addition. The fundamental conceptualization of the design has been on the basis of measurements carried out on a slightly older variant which exhibits appreciable performance.
4.    A summary of the technical details involved
The conceptualized device is a precisely bulk micromachined silicon-on-insulator micromechanical piezoresistive accelerometer with aircraft navigation being the primary application. Ion implanted piezoresistors connected through a metalized Wheatstone bridge which serves as the basic signal transduction element. Deep reactive ion etching is used for realization of the mechanical structure of the sensor. The low noise property of such sensors is achieved through proper doping and bulk micromachining of the structure while the operational mechanism ensures high linearity.
5.    Future prospects of the technology

With advancement in the automotive and aerospace sector, inertial navigation systems are becoming increasingly complex with a constant need for precision sensors to meet such requirements. As with any system, improvements are possible when the application is specifically defined and it is expected that this technology will prove to be a step in the right direction for the development of robust inertial sensors.

Inventors: Prof. Tarun Kanti Bhattacharya, Mr. Anindya Lal Roy

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