Investigation of the electrical stability of Si-nanowire biologically sensitive field-effect transistors with embedded Ag/AgCl pseudo reference electrode

We report on the electrical stability of Si-nanowire biologically sensitive field-effect transistors (BioFETs) fabricated using conventional microfabrication technique, with an embedded Ag/AgCl pseudo-reference electrode (pRE) formed by an electrochemical method. The open-circuit potential (OCP) characteristics between the pRE and a commercial reference electrode have been measured in order to evaluate the influence of the pRE potential on the device performance. In a pH sensing mode, the fabricated pRE follows the applied potential accurately with a small offset value of below 6 mV for pH in the range of 4 to 10. The BioFET was also used for the detection of alpha fetoprotein (AFP) with a detection limit of 10 pg mL^-1 and the corresponding OCP fluctuation of the pRE was less than 1.5 mV, independent of the AFP concentrations. These results suggest that the Si-NW BioFETs with the embedded Ag/AgCl pRE are very promising for reliable biosensing applications.