On-chip biosensor for rapid detection and identification of nitrogen containing compounds
K. Feige, A. Shende, A. Vats, R. Shende
South Dakota School of Mines & Technology, US
Keywords: on-chip sensor, detection, nitrogen compounds, military applications
Abstract:We present development of an on-chip biosensor that offers advantages of enhanced sensitivity over the existent methods, rapid detection, and portability besides being user friendly. Fabrication of our on-chip immunosensor to detect water-soluble nitro compounds is based on the miniaturization of microfluidic sensors developed for bacterial detection. Generation of an on-chip biosensor involves microfabrication techniques such as sequential deposition of mesoporous silica coating on a glass/Si wafer, coating of a photoresist and development of 20-200 micron size channels, lift-off, coating of platinum electrodes in the channels, and various surface modifications. The patterned wafer is then covered by a polydimethysiloxane layer. The mesoporous silica coating generates abundant hydroxyl groups for an improved antibody coating. An immunochemical bridge consisting of alternating layers of secondary and primary antibodies will further improve capture of the bacterial cells. In the preliminary fabricated devices, the electrodes will be connected using four point probe to the impedance analyzer. The on- chip senor will be calibrated by loading the bacterial solution of various concentrations and corresponding change in impedance will be recorded. In preliminary trial experiments, Anti-E.coli rabbit polyclonal antibodies were used and the change in electrical signal is currently being amplified. Various strategies for adapting this prototype to detect nitrocompounds on a chip will be discussed. In addition, data demonstrating the validation of the prototype will be presented.