Effect of Back-Gate Biasing on Floating Electrolytes in Silicon-on-Insulator-Based Nanoribbon Sensors

Silicon-on-insulator (SOI) field-effect-based sensors are often biased using a back substrate gate with biological/electrolytic solutions placed over the top sensor channel. For electrically floating electrolytes in contact with the SOI-buried oxide, we demonstrate that the electrolyte voltage is capacitively coupled to the applied back-gate bias resulting in a dual-gated sensor. Measured electrolyte voltages approach the constant back-gate voltage for real-time measurements, while a slower response is observed with dynamic measurements. Low subthreshold swings and threshold voltages are observed in both experimental and simulated - curves, consistent with strong coupling. Real-time constant voltage sensing can thus be performed at much lower operating voltages.