Area III: Wireless Sensors

We are developing a wireless sensing platform for environmental monitoring and detection that prohibits the use of wires. The first example is the development of resonator carbon nanotube sensing system. We have developed a vertically aligned carbon nanotube resonator sensor (Figure 1a) [J10, C12, and C19]. Upon exposure to ammonia, the sensor exhibits changes in resonant frequency to indicate the detection of gas (Figure 1b). Figure 2 demonstrates the concept of wireless sensing. The antenna of the passive sensor is used to receive an RF signal interrogated by a remote RF transmitter. The RF signal is stored and transduced through the carbon nanotube resonator. The signal is then reflected back to a remote RF receiver that will process the information for decision. The microwave carbon nanotube resonator sensor is a total passive device and requires no power. This type of passive sensor can be operated with several meters (up to 10 m) from the RF wireless reading system. Similarly, we have designed a strain gauge sensor using an F-inverted antenna (Figure 3) [D5, D6 and D7].

The application of wireless strain gauge sensors is the detection of strain and stress of compressor blades in aircraft turbines. By their nature as part of a shaft rotating at high speed, compressor blades are in motion during operation and undergo tremendous strain and stress during the operating cycles of the engines and over their entire life cycle. We are developing a wireless strain gauge sensor that has a size of a post-office stamp in multi-layer polymer materials and is a passive device. Current research is to develop a wireless biological sensing system funded by Air Force Office of Scientific Research.