Multiplexed Crossbar GFET Array With BioADC for Multimodal Aptamer-Based Sensing

We aimed to develop a scalable, low-power graphene field-effect transistor (GFET) crossbar array integrated with a neural-interface system-on-chip (NISoC), termed the GFET-NISoC platform, for multiplexed, real-time biomolecular sensing, including ultra-sensitive detection of $\boldsymbol{Pb}^{\mathbf 2+}$ using a G-quadruplex ssDNA aptamer. A 12 $\boldsymbol{\times}$ 12 GFET crossbar array was fabricated using a multilayer dielectric stack and optimized graphene transfer. Characterization was performed using both benchtop instrumentation and a low-power NISoC front-end supporting current- and voltage-clamp modes. Ionic strength, pH, and $\boldsymbol{Pb}^{\mathbf 2+}$ dose-response measurements were obtained from functionalized arrays. The platform demonstrated uniform Dirac behavior, reversible pH-dependent conductance, predictable ionic-strength responses, and femtomolar-level $\boldsymbol{Pb}^{\mathbf 2+}$ detection with strong selectivity over $\boldsymbol{Ca}^{\mathbf 2+}$ and $\boldsymbol{Co}^{\mathbf 2+}$ . The GFET-NISoC system enables multiplexed, multi-modal sensing at sub-µW power levels and provides a promising foundation for wearable or point-of-care chemical and biomolecular monitoring.