Label-Free Detection of Biomolecules Using Dielectric-Modulated Top Contact Bi-layer Electrodes Organic Thin Film Transistor

The dielectric-modulated top contact bi-layer electrodes organic thin-film transistor (DMTCBE-OTFT) based sensor is proposed to reduce the cost and complexity of nanoscale device fabrication for label-free biomolecule detection. In the proposed structure, a cavity is carved in gate dielectric and filled with biomolecules to realise the function of the sensor. The immobilisation of biomolecules in the cavity region alters the performance parameters like on-current (ION), on-off current ratio (ION/IOFF ), and subthreshold swing (SS) of the proposed device. We have also investigated the effects of gate work-function and cavity thickness on the sensitivity of a DMTCBE-OTFT based biosensor. A bi-layer electrodes is also used for a significant reduction in barrier height to enhance the performance of the proposed device. The change in the on-current (ION) and on-off current ratio (ION/IOFF ) has been utilised to evaluate the sensitivity of the DMTCBE-OTFT for biomolecule recognition. It has different dielectric constants and corresponding charge densities using 2-D simulation when biomolecules are immobilised in the cavity area. The ATLAS TCAD tool is used to investigate the sensitivity performance of the DMTCBE-OTFT. The proposed DMTCBEOTFT has almost four times higher drain current sensitivity in comparison to the recently reported OTFT-based biosensors for label-free detection of biomolecules. The DMTCBE-OTFT biosensor has enormous potential for future flexible biosensing applications due to its good sensitivity, flexibility, low cost, and biocompatibility.