Advanced biomolecule sensing: Simulation and sensitivity analysis of a dielectric-modulated bilayer electrode in DGOTFT

A dielectric-modulated bilayer electrode double-gate organic thin-film transistor (DMBE-DGOTFT), employing Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) as the active layer, is designed for selective and label-free biomolecule detection. The DMBE-DGOTFT biosensor leverages a biocavity integrated within the gate dielectric region, where the variations in dielectric constant and biomolecular charge density significantly influence the device electrical response. The key parameters, including Drain current variation, DNTT thickness, electric field distribution, charge polarity, and electrostatic potential—are systematically analyzed under diverse biosensing conditions using SILVACO ATLAS TCAD simulations. The DMBE-DGOTFT biosensor exhibits a maximum sensitivity of $4.5\times {10}^2$ for a charged biomolecule ($Q_f=1\times {10}^{12}{\text{cm}}^{-2}$) at a dielectric constant of 12, it demonstrates superior performance compared to conventional dielectric-modulated double-gate biosensors, with a sensitivity of 38.1. The dual-gate control and bilayer electrode configuration enhance charge transport and gate coupling, resulting in improved drain current modulation and detection accuracy. With its high sensitivity, real-time detection capability, biocompatibility, and suitability for scalable, low-cost fabrication, the DMBE-DGOTFT platform offers significant promise for next-generation applications in medical diagnostics, environmental monitoring, and point-of-care healthcare systems.