Optimization of silicon nanowire based field-effect pH sensor with back gate control

A field effect transistor (FET) sensor for pH detection was developed based on CMOS-compatible silicon nanowires. Optical lithography and anisotropic self-stop etching were employed to guarantee low cost and batch production for silicon nanowires. The pH nanosensor can detect the change of the hydrogen ion concentration effectively. In addition, it is demonstrated that the back gate electrode can tune the nanowire detection sensitivity, which can be optimized and exponentially enhanced in the subthreshold regime. The development of a nanoscale sensor with physically engineered gates offers the possibility of highly parallel labeling and detection of chemical and biological molecules with selective control of individual array elements in a single integrated chip.