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Chemical Sensors

Developing chemical species sensors for aerospace applications including leak detection, emission, safety, human health, and environmental monitoring.

NASA’s Glenn Research Center Chemical Species Gas Sensors Team is developing microsensing technology for aerospace applications. The approach is to provide sensitive and selective sensor systems able to provide quantitative measurements of the environment and thus allow better cognition and decision making. The sensors can be used for leak detection, emission, safety, human health, and environmental monitoring. The resulting sensor system is meant to be small, smart, and rugged with capabilities tailored for the targeted application.

The program develops four different types of sensor platforms for chemical sensing. One platform is a Schottky diode sensor structure for use in very sensitive measurements. The detection of low concentrations of hydrogen and hydrocarbons can be achieved by using this basic structure. Three other platforms, resistive-based techniques, electrochemical cells, and nanoplasmonic structures, are used depending on the species and concentration range to be detected.

The use of these platforms to produce sensor arrays is an on-going activity of this group. For example, one goal of this gas sensor research is to create a microfabricated gas sensor array operable at high temperatures such as in an emissions stream. Since one sensor will not be able to characterize multiple species in such an environment, an array of high-temperature sensors is necessary.

One embodiment of a microfabricated SiC based hydrogen and hydrocarbon sensor.

This array, effectively a high-temperature electronic nose, is a significant step in allowing the monitoring and/or control of emissions produced by an aeronautic engine. The signals produced by this sensor array could be analyzed to determine the constituents of the emission stream.

This information could then be used to control those emissions. Sensor arrays have also been developed for other applications.

Sensor Platform Approach

These sensors are microfabricated using Microelectromechanical Systems (MEMS) based technology to minimize size, weight, and power consumption. Nanostructures are used to improve the sensor response and stability and can be integrated into microstructures. A temperature detector and a heater are standardly included in the sensor structure to allow stable sensor operation at a variety of temperatures.

Mass fabrication of the sensors using silicon-processing technology is envisioned to minimize the cost per sensor. The program develops four different types of base sensor platforms. One platform is a Schottky diode sensor structure for use in very sensitive measurements. Two other platforms, resistor-based techniques, and electrochemical cells are used depending on the gas and concentration range to be detected. Another platform takes advantage of the unique capabilities provided by nanoplasmonic sensors.

These sensor platforms are foundations on which a wide range of species may be measured by choice of materials and operating parameters. For example, the electrochemical cell platform can be modified to produce an oxygen sensor or a carbon dioxide sensor depending on the electrolyte, materials, and operating temperature.

Integration into Smart Sensors System

The sensors developed from these platforms allow the detection of a range of species including hydrogen, hydrocarbons, nitrogen oxides, carbon monoxide, oxygen, and carbon dioxide in a variety of ambient gas conditions and temperatures. A core foundation of this work is the integration of these sensors, either individually or in a sensor array, into Smart Sensor Systems.

A Smart Sensor System, as conceived of here, is a complete self-contained sensor system that includes multiparameter sensing, data logging, processing and analysis, self-contained power, and an ability to transmit or display information.

Multiparameter information is obtained to understand the environment. Local processing is used to optimize the quality and relevance of that information and then it is communicated in a manner that best fits the application. The approach has been to develop “Lick and Stick” technology that can be stand-alone and applied wherever and whenever necessary.

Wide Range of Applications

The application range of this technology has been broad and impactful. Applications over time have included leak detection, fire and environmental monitoring, engine emissions, and human breath and exercise monitoring, and cryogenic fuel line monitoring.

The work has often involved collaborators such as Case Western Reserve University and Ohio State University, as well as hardware development in the STTR and SBIR program by Makel Engineering, Inc.

Applications of the technology developed in this work range from the International Space Station to the surface of Venus. This website gives a sampling of the sensors, sensor arrays, and their applications.

Selected Awards:

  • NASA Invention of the Year Honorable Mention (2017)
  • Vehicle Integrated Propulsion Research (VIPR) Group Achievement Award (2016)
  • Abe Silverstein Medal For Exceptional Technical Achievement (2011)
  • Outstanding Paper of the Year, Sensors Review Journal (2011)
  • Nominated for NASA Invention of the Year (2009)
  • Nano 50 Award for Advancement of Nanotechnology (2008)
  • R&D 100 Award for Fire Detection System (2005)
  • NASA Turning Goals into Reality Associate Administrators Choice Award (2005)
  • NASA Turning Goals into Reality Safety Award (2003)
  • R&D 100 Award for Leak Detection System (1995)
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