Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

• Goals: To perform true systems integration for existing or incrementally advanced sensor technologies in such a way as to meet system-level constraints related to:

• power consumption

• robustness in real-world environments

• auto-calibration capability

• small size, portable deployment

• self-diagnostic capability

• multi-stimulus detection

• sensitivity limits

without sacrificing stimulus recognition capability

Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

Areas of Research in Microsystems Development• Chemical Sensing Microsystems

• Modeling of front-end olfaction in sensor array design and architecture to enhance system robustness, resilience to broken sensors, auto-calibration capability, and sensitivity floor (detection limit).

• Streamlining of signal processing to adapt chemical discrimination algorithms to lower-overhead equivalents for implementation in portable systems

• Sensor platform development for extraction of multiple features from a single micro-sensor in an array (including instrument development)

• Miniaturization of existing larger chemical sensors and systems

• Optimization of signal conditioning and readout circuits to reduce superfluous information and enhance signal-to-noise ratios

Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

Areas of Research in Microsystems Development• Chemical Sensing Microsystems: Available Sensor Technologies

• ChemFETs: • streamlined signal processing, • sensor platform development, • miniaturization of systems, • optimization of signal conditioning.

• Composite Polymer Sensors: • olfactory modeling, • streamlined signal processing, • sensor platform development, • miniaturization

• Metal-oxide Sensors: • olfactory modeling, • sensor platform development

• SPR (surface plasmon resonance): • streamlined signal processing; • miniaturization of systems

Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

Areas of Research in Microsystems Development• Other Microsystems

• Development of application specific integrated CMOS imagers and auditory systems modeled after biology

• Development of imaging and auditory microsystems for streamlined, low-power implementation

• Development of integrated pressure sensors for characterizing and controlling biopsy sample preparation

• Development of integrated platforms for evaluating fluorescence of living, dead, and lysed cells

• Radio Frequency Identification systems for monitoring health of trees to increase their market value (and thereby decrease the number of trees that need to be cut down).

Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

• What Drives Research in this Laboratory? (e.g. the Vision)• LINK TO INDUSTRY: THE APPLICATIONS

• Environment

• Environmental monitoring and remediation (groundwater and airborne pollutants)

• Protecting health and welfare of human beings

• Chemical and Biological Warfare Sensor Systems useful for widespread distributed implementation

• Improved Sensor Systems for Biomedical Research

• ENGINEERING PERSPECTIVE: SYSTEMS INTEGRATION

• MAUV

• SCIENCE PERSPECTIVE: MODELLING OF BIOLOGY

• Olfactory, Auditory, and Vision Modelling

Distributed Microsystems Laboratory:Distributed Microsystems Laboratory:Developing Microsystems that Make SenseDeveloping Microsystems that Make Sense

• What Drives Research in this Laboratory? (e.g. the Vision)• PERSONAL PERSPECTIVE AND CONVICTIONS

• Teaching• “Classes”: critical thinking are weighted as heavily as topical skills• “Laboratory”: teamwork, maturity and responsibility, long-term

potential and vision of students should be developed with as much seriousness as the topical experience. Don’t clone graduate students!

• Use (constructive) criticism and high expectations as a tool to driving students toward reaching their potential.

• Research: • No weapons of mass destruction ever• Keep “making the world a better place” at the top of the priority list

• Service:• Be kind, give easily, don’t get overextended.

SPR (Surface Plasmon Resonance) SPR (Surface Plasmon Resonance) Chemical Sensing MicrosystemsChemical Sensing Microsystems

Collaboration with Karl Booksh, Department of Chemistry, Arizona State University

Polychromatic Light

Inlet Port

Outlet Port

Chemically sensitive coating

Gold Interface layer

Waveguide

Dielectric Color Filter

Photodiode

Silicon Substrate

SPR (Surface Plasmon Resonance) SPR (Surface Plasmon Resonance) Chemical Sensing MicrosystemsChemical Sensing Microsystems

Chemically sensitive coating

Waveguide

Gold Interface layer

Analog Photodiode

Outputs

timeDigital Alarm

Outputs

Chemical Sensing Chemical Sensing MicroMicroSystems: Systems: Modeled after Front-End OlfactionModeled after Front-End Olfaction

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 Conducting Polymer

Chemical Sensing Systems: Chemical Sensing Systems: What does front-end olfaction tell us?What does front-end olfaction tell us?

Source: Kendall and Schwartz; Principles of Neural Science

• Fact: Olfactory Mucous pre-concentration ignores odors beyond a saturation level and below a threshold level

• Engineering Implication: concentration detection and odor discrimination should be performed independent of one other

Scale-Invariant A/D Conversion Scale-Invariant A/D Conversion applied to a CMOS Imagerapplied to a CMOS Imager

System ArchitectureSystem Architecture

...

... ...

...

......

Photodiode/transistor

Focal Plane Processing,Integrating/Reset Circuits

Pixel Selection,Digital Readout Circuits,Readout Amplifiers

Global Communication(for automatic gain control),Control/Readout Lines

Scale-Invariant A/D Conversion Scale-Invariant A/D Conversion applied to a CMOS Imagerapplied to a CMOS Imager

Ratio-based A/D Conversion: ExampleRatio-based A/D Conversion: Example

75/25 high/low

Original Image

50/50 high/low

25/75 high/low

2-bit converted image

Chemical Sensing Chemical Sensing MicroMicrosystems: systems: Scaling Down Larger SystemsScaling Down Larger Systems

• Scale: centimeter-size Capteur sensors to micron-size sensors

• Additional capability: two electrode widths determine whether analyte penetrates into the bulk or remains on the surface of the sensor; provides additional information with which to discriminate analytes

• Performance Improvements: lower power, faster response time for both sensors and sensor heaters

Chemical Sensing Chemical Sensing MicroMicrosystems: systems: Overcoming CMOS Compatibility IssuesOvercoming CMOS Compatibility Issues

• Problem: surface non-uniformity causes non-uniform chemical sensing film deposition

• Solution: use vertical sidewalls as sensor surface coatings

• Problem: conventional silicon direction-selective etching attacks bonding pads and other exposed aluminum

• Solution: use different sensor platform architectures that enable dry, isotropic etch