Description: The Naval Research Laboratory (NRL) has developed a technology for detecting chemical vapors using low power, low cost, tunable microsensors. This technology is based on metal nanoparticles encapsulated by a single layer of organic molecules. When configured as a film of nanoparticles connected to a small bias current, exposure to a vapor causes conductance changes in the film. The conductance path through the film involves electron tunneling across the somewhat insulating monolayer junctions between nanoparticle conducting cores – referred to as a nanometer-scale metal-insulator-metal ensemble (MIME). Tuning these MIME sensors to a particular vapor is accomplished by designing the structure of the organic molecule in the encapsulating shell to interact with that particular vapor.

Advantages/Features Include:

  • Tunable to analyte of interest
  • High sensitivity - better than ppm
  • Low power (milliwatts to microwatts) and low cost (disposable)
  • Rapid response time - 0.1 to 10 seconds
  • Integrates with planar lithography
  • Portable - can be integrated into a handheld device

Applications Include:

  • Medical Diagostics - breath analysis
  • Chemical and Explosive Vapor Detection
  • Substance Identification - "electronic nose"
  • Air Monitoring

References:

  • "Colloidal Metal-Insulator-Metal-Ensemble Chemiresistor Sensor" Anal. Chem. 1998, 70 (14), 2856 - 2859.
  • "Scaling Properties of Gold Nanocluster Chemiresistor Sensors" IEEE Sensors Journal 2006, 6 (6), 1403 - 1414.
  • "MIME Chemical Vapor Microsensors," NRL Review 2002.

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