The capability to differentiate different types of explosives, as well as fresh and aged explosive residues, is very important in determining the level of threat of a suspected explosive device and devising effective response to it. In close collaboration with Antao Chen group at Applied Physics Laboratory at UW, we have developed thin films explosive sensors based on the random nanowires of n-type semiconductor metal oxides such as ZnO and TiO2 that can respond very sensitively to trace vapor of explosives. These sensors behave like a resistor and their resistance changes significantly and rapidly when explosive vapor is in close contact with surfaces of nanowires. Because the electron charge carriers are reduced in the depletion region, the electric resistance of the nanowires can increase significantly, and the extremely large surface-to-volume ratio of nanowires also contributes significantly to the sensitivity of the response. Our current focus is to develop rationally designed materials and techniques for surface functionalization of semiconducting nanowire surfaces to specifically interact with different types of chemical vapors of interest. We are applying developed surface functionalization methods to integrated silicon nanowires also.
- Development of semiconducting nanowire sensors of explosive degradation products (ONR-SAAET).
- Development of portable chemiresistive nanowire explosive sensors (ONR).
- Development of chemiresistive TiO2 nanowire explosive sensors (ONR-SAAET).
Research Highlights: Contact for detail (jangsh (at) u.washington.edu)
Schematic illustration and SEM of fabricated silicon nanowire sensors
- D. Wang, H. Sun, A. Chen, S.-H. Jang, A. K.-Y. Jen, and A. Szep, “Chemiresistive Response of Silicon Nanowires to Trace Vapor of Nitro Explosives,” Nanoscale 2012, 4, 2628.
- D. Wang, A. Chen, S.-H. Jang, H.-L. Yip, and A. K.-y. Jen, “Sensitivity of Titania (B) Nanowires to Nitroaromatic and Nitroamino Explosives at Room Temperature via Surface Hydroxy Groups”, J. Mater. Chem. 2011, 21, 7269.
- D. Wang, A. Chen, S.-H. Jang, J. Davies, and A. K.-Y. Jen, “The Effect of Dipole Moment and Electron Deficiency of Analytes on the Chemiresistive Response of TiO2(B) Nanowires,” Analyst 2011,136, 4179.
Current Team Members: Dr. Sei-Hum Jang, Jeffrey Yang, and Andrew Nguyen
Research Collaborator: A. Chen (UW, APL)
Related Interests and Keywords: semiconducting nanowire, nanowire films, titanium dioxide nanowire, silicon nanowire, chemiregistor, semiconducting nanowire field-effect transistor, surface modification of nanostructures.