Effect of liquid gate bias rising time in pH sensors based on Si nanowire ion sensitive field effect transistors

摘要

Highlights•Experimental investigation in pH sensors based on SiNW ISFETs.•The effect of the rising time (TR) of the liquid gate bias on transient response.•Rising time (TR) and pH-dependent ISFET current.•Importance of retardation of mobile ions in terms of biosensor design.AbstractIn this study, we investigate the effect of rising time (TR) of liquid gate bias (VLG) on transient responses in pH sensors based on Si nanowire ion-sensitive field-effect transistors (ISFETs). As TRbecomes shorter and pH values decrease, the ISFET current takes a longer time to saturate to the pH-dependent steady-state value. By correlating VLGwith the internal gate-to-source voltage of the ISFET, we found that this effect occurs when the drift/diffusion of mobile ions in analytes in response to VLGis delayed. This gives us useful insight on the design of ISFET-based point-of-care circuits and systems, particularly with respect to determining an appropriate rising time for the liquid gate bias.