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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 - PowerPoint PPT Presentation
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Mems Sensors For Harsh Environment
ARUN K M10MBE0003
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