Chemical Sensing

Technology

More so than ever, extreme detection with high selectivity of chemical and biological species and pathogens is becoming critical for our defense and civilian security. SemaDyne’s patented technology utilizes the bimaterial effect to detect a range of chemical analytes in the environment. The selective layer sorps the analyte vapor from the ambient and the physical change in the sensitive and selective layer results in a change in the bimaterial structure (deflection, resonance frequency, Q-factor). The changes are detected and quantified to the analyte concentration in the ambient. The response of the sensor to fast varying humidity conditions is monitored by the bimaterial structure with high fidelity (shown in the image). High sensitivity and extremely fast response, which are unique attributes of SemaDyne’s chemical sensors, are achieved by a fine control over the physical and chemical attributes of the sensitive layers. The sensor chips are designed and fabricated using a number of sensitive layers pertinent to the application at hand (monitoring industrial process, humidity, TTHMs in water, explosives detection).

Applications

  • Monitoring Industrial Processes
  • Detection of Green House Gasses
  • Detection of VOCs
  • Measuring TTHMs
  • Explosive Detection
  • High Accuracy Humidity Monitoring

Features

  • High reliability
  • High sensitivity (sub-ppb)
  • Excellent selectivity (nearly 4 order difference)
  • Fast response (few msec)
  • Large dynamic range (low ppb to saturated vapors)
  • Long term stability (>2 years)
  • Low drift
  • Low hysteresis
  • Easy operation
  • Easy to replace the sensor chips
  • Low calibration and recalibration requirements
  • Miniature size

Related Videos

This movie shows the response of a humidity sensing bimorph sensor in a 90% humid environment that is randomly exposed to a stream of nitrogen.  An identical cantilever with no coating is shown as a reference to indicate the effect of the dry nitrogen stream. 
This movie shows the response of a humidity sensing bimorph sensor in a 90% humid environment that is exposed to a stream of nitrogen that is passed through a chopper.  An identical cantilever with no coating is shown as a reference to indicate the effect of the dry nitrogen stream.

Published Papers

  • Srikanth Singamaneni, Michael E. McConney, Melburne C. LeMieux, Hao Jiang, Jesse O. Enlow, Timothy J. Bunning, Rajesh R. Naik, and Vladimir V. Tsukruk. Polymer-Silicon Flexible Structure for Fast Chemical Vapor Detection. Advanced Materials (19) 4248-4255. 2007. [PDF]
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