1. Mems Sensors For Harsh Environment
ARUN K M
10MBE0003

2. Radation meter

3. 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

4. Ambient Conditions High temperature High amount of Vibrations
High pressure

5. 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

6. 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 ( eV) a higher thermal conductivity ( W/cm K)
high saturation velocity (cm/s)

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

8. 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

9. Types
Fibre Optic Sensor
Moems Fabrey Perot Sensor

10. 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

11. 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

14. 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

15. 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