1. Distributed Microsystems Laboratory: Developing Microsystems that Make Sense Portable Chemical Sensing Systems Development Sponsoring Agency: National Science Foundation CAREER Award #: #ECS-9996263 Period of Award: 6/97-5/01 PI: D. Wilson Research Assistants: Sam McKennoch, Sean Hoyt Collaborators: Nate Lewis, Caltech; Jiri Janata, Georgia Tech

2. Distributed Microsystems Laboratory: Developing Microsystems that Make Sense Goals: To develop a proof-of-concept portable chemical sensing instrument that provides field portable, continuous monitoring of vapor-phase chemicals with the following features: On-board sampling/airflow control Low power Use of human pattern recognition capability to decrease system power and false alarm rates small size, portable deployment self-diagnostic capability multi-stimulus detection without sacrificing stimulus recognition capability

3. Distributed Microsystems Laboratory Portable Chemical Sensing Systems Development Incoming Airflow Vapor Sample Incoming Airflow Vapor Sample Heater Chemically Sensitive Coating Pre-concentrator Microcontroller: Streamlined Pattern Recognition (low-power) Aggregation Signal Conditioning Signal Screening Heater Control A/D Conversion (as needed) Metal-oxide or Polymer (Maximally Diverse; Broad Selectivity; Low-to-Moderate Precision

4. Array of 6 sensors is projected onto principal component space with on-board noise reduction. User can observe path that an unknown analyte travels to determine which analyte is present in the sensing environment. User-visual intervention reduces false alarms and provides more powerful pattern recognition in a low-power envelope. Distributed Microsystems Laboratory Portable Chemical Sensing Systems Development Methanol Calibration Point Response Path Recovery Path

5. Proof-of-concept Instrument (Interface) Discrete Sensors Discrete Processing Circuits PIC Microcontroller 4 9V Batteries Discrete version consumes a total system power of 15W; integrated version will reduce power consumption by one order of magnitude or more Distributed Microsystems Laboratory Portable Chemical Sensing Systems Development

6. Proof-of-concept Instrument (Sensor Array) 6 metal-oxide sensors (discrete) Heater control circuits Sampling flow chamber Discrete version consumes a total system power of 15W; integrated version will reduce power consumption by one order of magnitude or more. Distributed Microsystems Laboratory Portable Chemical Sensing Systems Development

7. Modular Sensor Interface Boards metal-oxide sensors (discrete) ChemFET sensors or composite Polymer sensors Up to 8 different types of sensors (16 total sensors) can be accommodated by the interface electronics Information from 2-8 sensors is projected onto two-dimensional space and calibration points for up to 24 analytes can be plotted on the user display. Distributed Microsystems Laboratory Portable Chemical Sensing Systems Development