- Sensing reactive gas species in vacuum lines and abatement systems
- Gas sensing, e.g., relative humidity, for HVAC applications
Conductometric gas sensors, based on semiconducting metal oxide films, are widely used in gas sensing due to their simplicity, flexibility in production, and broad applicability. Typically, the adsorption of a gas molecule on the surface of a metal oxide film alters surface electronic properties, causing a change in electrical conductivity, which can be measured with simple electronics. Unfortunately, many metal oxides used in sensing suffer from low catalytic activity, reducing device sensitivity. Resolving this problem requires doping with expensive noble metal nanoparticles, thereby precluding the use of these sensors in low-cost applications.
The technology is a low-cost graphene oxide conductometric gas sensor that uses an ultrathin film made of graphene oxide (GO) nanoflakes for transduction. GO is used as the active material for conductometric gas sensing due to its high sensitivity to reactive gases and harsh environmental compatibility. The fabrication process uses electrospray printing without needing high temperature or high vacuum processing conditions, but allows for precise control of film properties, is compatible with low-cost, large-area manufacturing and can use a variety of feedstock liquid suspensions. The printed graphene oxide devices successfully detected ammonia at concentrations down to 500 parts per million in a vacuum at 1 Torr pressure, and was able to measure relative humidity in atmospheric pressure stabilizing in less than a minute.
- Excellent for low-cost applications with high signal-to-noise ratio in device outputs
- Compatibility with harsh environments
- Linear response to humidity in the 7-63% relative humidity range
- Dynamic response of GO sensors equivalent to commercial humidity sensors
- No post heat treatment, harsh chemical reduction or doping with metal nanoparticles
- Real-time monitoring of relative humidity
- Active area an order of magnitude smaller than competing humidity sensors