Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode Device
electrical and electronics
Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode Device (LEW-TOPS-42)
Novel microsensor signals when toxic gases or explosives are present
NASA's Glenn Research Center has developed a groundbreaking new microsensor that detects toxic gases and explosives in a variety of environments. Most devices can perform only a unidirectional sensing task, lacking a switching feature that would allow the device to return to baseline operation after the volatile species is removed or has dissipated. Glenn's nano-Switch Sensor Schottky Diode (nanoSSSD) device consists of a thin film of graphene deposited on a specially prepared silicon wafer. Graphene's two-dimensional properties make this technology both extremely sensitive to different gases and highly reliable in harsh, enclosed, or embedded conditions. The nanoSSSD can be connected to a visual and/or sound alarm that is autonomously triggered as the sensor detects a selected gas and then returned to its passive mode when the gas is no longer present. The innovation has applications in biomedical devices, combustion engines, and detection/switching devices used in mass transit systems.
Glenn's graphene-based nanoSSSD provides dual-use functionality and reversibility characteristics in a compact and reliable package. The nanoSSSD can be connected to a visual and/or sound alarm that autonomously triggers in the presence of specially selected gases, such as ammonia, hydrogen, hydrocarbons, nitrogen oxides, or carbon monoxide. The device includes a doped substrate, an insulating layer disposed on the substrate, an electrode formed on the insulating layer, and one or more thin films of graphene deposited on an electrodized, doped silicon wafer. The graphene film acts as a conductive path between a gold electrode deposited on top of a silicon dioxide layer and the reversible side of the silicon wafer, so as to form a Schottky diode. The substrate in Glenn's innovative device can be fabricated with either n-doped or p-doped silicon, allowing the device to achieve enhanced compatibility with specific silicon-based nanoelectronic circuits as required. The graphene's two-dimensional nature maximizes the sensing area, and the device itself contains no moving parts, unlike other devices that offer dual switching/sensing functionality, which often make use of mechanical actuators such as cantilevers. Those devices are more complex to fabricate and more likely to reduce the mean-time-to-failure. By contrast, the relative simplicity of the Glenn nanoSSSD makes it more robust and therefore lends itself to settings where frequent replacement is not an option. This mechanism has the potential to revolutionize sensing/switching applications from embedded biomedical devices to jet turbine engines to homeland security screening systems.
- Robust: Operates in harsh or difficult-to-access conditions
- Reliable: Contains no moving parts and thus offers longer mean time to failure
- Dual-use functionality: Operates as a sensor or as a switch, or both, depending on the application's requirements and objectives
- Versatile: Permits greater compatibility with specific silicon-based nanoelectronic circuits, because it can be fabricated using either n-doped or p-doped silicon
- Economical: Features a simplified fabrication process and a vertical configuration, which reduces cost and frees up circuit area
- Environmental monitoring
- Engine optimization
- Transportation (detection/switching devices)
electrical and electronics