Innovators at NASA's Glenn Research Center have developed a unique nano-structure device that operates as a nano-switch/sensor for detecting toxic gases and ultraviolet (UV) radiation. Conventional microsensors are limited by their short life, high cost and complexity, and unifunctional sensing task. Glenn's novel Polymer Nanofiber-Based Reversible Nano-Switch/Sensor Schottky Diode (nanoSSSD) technology offers the ability to respond to changing conditions and then revert to baseline operations when conditions return to normal. Glenn's nanoSSSD features no mechanical moving parts, and the sensors are reusable after annealing, extending their appeal for rapid-response, low-cost devices. This simple design provides an easily fabricated, mass-producible microsensor for use in numerous applications where replacement opportunities are limited.
Glenn's innovative nanoSSSD device includes a doped semiconducting substrate, an insulating layer deposited on the substrate, an electrode formed on the insulating layer, and at least one polymer nanofiber deposited on the electrode. The deposited nanofiber provides an electrical connection between the electrode and the substrate, serving as the electroactive element in the device. The nanofiber is generally composed of a customized polymer (e.g., polyaniline) that is extremely sensitive to the adsorption and desorption of a single gas molecule. As gas molecules are adsorbed and desorbed, the resistivity of the customized polymer also changes, providing its sensing capacity. When the nanoSSSD device senses a selected gaseous species, the switching portion of the device automatically actuates, sending a signal to the control component. This control component activates the output (warning) device. In addition to its ability to detect harmful gases (including ammonia, hydrogen, hydrocarbons, nitrogen oxides, carbon-monoxide, and carbon dioxide), Glenn's device can also feature conducting polymers that are sensitive to UV radiation. Glenn's nanoSSSD technology has great commercial potential, particularly in situations where frequent replacement of the switch/sensor is impractical.