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Mems Sensors For Harsh Environment. ARUN K M 10MBE0003. Radiation sources in our Environment. Watch and clock faces (radium dial) G as lamp mantles(thorium oxide) Pink glass and jewelry polishing compound Smoke detectors N uclear power reactor losses(JAPAN!!!) Airplane flights
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Mems Sensors For Harsh Environment ARUN K M 10MBE0003
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 • MoemsFabrey 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 espectto 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 , ClaesMattsson2009 • 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 , ClaesMattsson 2009