A New Micromachined Sensor Platform. Debra J. Deininger Synkera Technologies Inc. June 6, 2007

Transcription

1 A New Micromachined Sensor Platform Debra J. Deininger Synkera Technologies Inc. June 6, 2007

2 Outline Review of sensor requirements Fabrication of the sensor platform Nanotechnology Ceramic MEMS Applications Summary & Conclusions Questions? Comments? Suggestions?

3 What makes a good sensor? Performance Reliability Reproducibility Low power consumption Portable applications Small size

4 Anodic Alumina: An Enabling Material for Nanotechnology Nanoporous Architecture Pore sizes nm Thickness 1µm m (supported) 100 s µm Ceramic Material Thermal stability Mechanical stability Chemical stability d pore H aao D cell d pore

5 Anodic Alumina: An Enabling Material for Ceramic MEMS Hybrid (surface & bulk) micromachining, 3-D D possible High resolution (2-3 µm), high aspect ratio (1:60) features

6 Gas Microsensor Platform #1 I s sensing electrode V s Sensing element µ-heater V h Sensing Material inside the pores of AAO Sensing Element Sensor Substrate #2 V s I s sensing electrodes sensing element Sensor support Sensing material on top of microheater µ-heater V h Sensor Substrate Sensor types implemented to date: #1 (sensing materials inside nanopores): : catalytic combustible, conductimetric,, acoustic #2 (sensing material on top of microheater): : conductimetric with existing sensing materials composition, potentiometric US Pat. 6,705,152 B2 (03/16/04)

7 Application: Chemiresistor Sensors Detects toxic and combustible gases Semiconductor material changes resistance Relatively non- selective Sensor Features Robust, long lasting High sensitivity Nanostructured sensing material Low power Microsensor design Selectivity enhanced via materials selection and operating modes

8 Chemiresistor Sensor Case Study 120% 4.5E-07 Sensor Response 100% 80% 60% 40% 20% Sensor Response (A) 4.0E E E E E E E E-08 Arsine Phosphine H2 Air 0% ~30 ppb arsine ~60 ppb arsine ~150 ppb phosphine ~300 ppb phosphine 0.0E concentration test gas Sensitive and selective hydride detection

9 Chemiresistor Sensor Case Study Sensor response curves (ppm( ppm) ppm Arsine ppm Phosphine Arsine Phosphine Sensor Response (ohm 1.E+09 1.E+08 1.E Time (mins)

10 Application - Pellistors Detects combustible gases Based on catalysis at sensor surface Changes resistance of Pt heater Usually operated in bridge configuration Features LEL detection Linear response Detects many different combustible gases Widely used

11 Application: Pellistors Nanoengineered Sensing Element Micromachined Ceramic Sensor Substrate Packaged Gas Microsensor Operating in Air at T>1100 C

12 Application: Pellistors Temperature, o C µm 50 µm 150 µm 600 µm Power, mw Temperature, C Heater OFF Heater ON Time, s 90% set point Microheater power consumption Microheater response time

13 Pellistor Case Study Step change response 0-2.5% of CH 4 T=330 to 625 C Response to 2.5% CH 4 Surface area effect ~80 m 2 /g Signal, V ~3 m 2 /g ~ 40 m 2 /g Temperature, C

14 Application: Acoustic Sensors Acoustic sensors Very low power, good sensitivity Able to detect a wide range of analytes Widely used in homeland security sensing applications

15 Summary and Conclusions Factors driving sensor design Sensitivity Selectivity Low power / portability Affordability Combining MEMS and nanotechnology to engineer sensor performance

16 Acknowledgements Synkera Technologies Stephen S. Williams Dmitri Routkevitch Clayton J. Kostelecky Oleg Polyakov Rikard Wind Erica J. Benstock John Valdez Funding NIOSH SBIR Grant New Nanostructured Sensing Arrays for Hydride Detection NIOSH SBIR Grant Advanced Personal Gas Detectors for Mining Applications