Single metal and conducting polymer nanowire sensors for chemical and DNA detections

Due to the small size, sensitivity, real time detection, and ultra-low power demands, nanowire sensors are being investigated for detection of a wide range of chemical and biochemical species. However, techniques used to fabricate these nanowire sensors have drawbacks of limited controllability and manufacturability. Reliable and controllable nanowire fabrication remains a significant challenge. In this work, we have developed a fabrication technique that is potentially capable of producing arrays of individually addressable nanowire sensors with controlled dimensions, positions, alignments, and chemical compositions and are in the process of fabricating sensor arrays to detect gases, and biochemicals. Fabrication of single Pd nanowires with diameters from 70 nm to 300 rim and up to 7 mu m in length will be presented. These nanowires are used to sense hydrogen gas at concentrations as low as 0.02% and show a response time of 300 msec with an operating power of 350 nW. We also recently demonstrated the feasibility of fabricating single polypyrrole and polyaniline nanowires and their application as DNA sensor (1 nM). Currently, we are investigating single nanowire field effect transistors (SNWFET) for possible applications which include label-free DNA detection, early detection of disease signatures, and environmental monitoring.