Transcript Mems Sensors For Harsh Environment

Mems Sensors For Harsh
Environment
ARUN K M
10MBE0003
Radation meter
Radiation sources in our
Environment
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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
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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
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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