Biochemical sensing of charged polyelectrolytes with a novel CMOS floating-gate device architecture

Novel CMOS device is proposed as a biochemical sensor. We modified the basic architecture of an extended floating-gate field-effect transistor (FET) to be suited for VLSI applications. The FET has a floating-gate that is umbrella-shaped (UGFET), maximizing its charge sensing area in a much reduced transistor area. Compared to previous extended floating-gate structures, the UGFET shows improved scalability and sensitivity. 3-D device simulations validate the UGFET model. The design is fabricated in a standard CMOS process and characterized. Experimental results are presented employing transconductance and subthreshold measurement schemes which confirm its high sensitivity and workability.