This study presents the design and simulation of a graphene-channel, aluminum oxide sensing, dual-gate ISFET architecture integrated with a differential analog readout circuit for wide-range \(\text{p}\text{H}\) sensing applications. The system was evaluated using a combination of TCAD-based physical device modeling and Verilog-A-level circuit co-simulation to capture both device physics and system-level behavior. Simulations were conducted across the full \(\text{p}\text{H}\) spectrum from 1 to 14, and the sensor exhibited a monotonic current response with an average sensitivity of \(1063 \;\text{m}\text{V}/\text{p}\text{H}\) . The local sensitivity varied from \(-606\) to \(-1455 \;\text{m}\text{V}/\text{p}\text{H}\) , while the linearity of the output was confirmed with a coefficient of determination of \({R}^{2}=0.984\) . Unlike many previously reported ISFET designs that offer high sensitivity over limited \(pH\) intervals, the proposed sensor maintains consistently high transduction performance across acidic, neutral, and alkaline ranges. The integration of a graphene channel and \({\text{Al}}_{2}{\text{O}}_{3}\) sensing membrane, combined with dual-gate capacitive control and a custom analog readout stage, enables strong signal amplification and wide-range operability. These features, along with full-system modeling and validation, position the proposed design as a promising platform for future experimental realization in portable, wearable, or lab-on-chip bio sensing applications.
