Mems Sensors For Harsh Environment ARUN K M 10MBE0003

Radation meter

Radiation sources in our Environment Watch and clock faces (radium dial) Gas lamp mantles(thorium oxide) Pink glass and jewelry polishing compound Smoke detectors Nuclear power reactor losses(JAPAN!!!) Airplane flights Radon gas Gemstones

Ambient Conditions High temperature High amount of Vibrations High pressure

High Temperature Sensors Normal Si sensors fails at >180°C Cooling required-more weight SiC and Group 3 nitrides-smart mems sensor SiC-Challenges in micromachining G3 nitrides-piezoelectric functional elements(upto 1500ºC) MOEMS-better remote sensing application

Sic- Properties Outstanding material and electronic properties and chemical inertness hardness of 2480 kg/mm2 Young’s Modulus of 700 Gpa SiC has a larger bandgap (2.3-3.4 eV) a higher thermal conductivity (3.2-4.9 W/cm K) high saturation velocity (cm/s)

Types Piezoresistive Capacitive -based sensors Pressure , force and acceleration HT applications

MOEMS sensors Measure pressure,temperature,stress,displacement Can easily incorporated in sensor arrays Can be used for gas and liquid measurements Highly resistant to electromagnetic interference (EMI) and radio frequency interference (RFI) Eliminate the necessity of onboard electronics

Types Fibre Optic Sensor Moems Fabrey Perot Sensor

Fibre Optic Sensors Robust, highly resistant to EMI and RFI Detect displacements on a sub-nanometer scale The fabrication is complicated and expensive. Misalignments between the sensor and the fiber

MFPD Do not require alignment and stabilization techniques a cantilever beam fabricated in low-stress LPCVD silicon nitride forms top mirror of interferometer silicon substrate below provides the bottom mirror substrate vibrates, there is a relative deflection of the beam with espect to the substrate and hence a change in the microcavity height. the amplitude of the substrate motion can be calculated

Polymer Sensor Design, Fabrication and Optimization of Thermal Radiation Detectors Based on Thin Polymer Membranes , Claes Mattsson 2009 a new application of SU-8 as a closed membrane in a thermal sensor. Calibrated with bolometer

Reference New Trends on MEMS Sensor Technology for Harsh Environment Applications Patricia M. Nieva Design, Fabrication and Optimization of Thermal Radiation Detectors Based on Thin Polymer Membranes , Claes Mattsson 2009