Advancing Ultrasensitive, Drift-Correcting Dual Floating Gate Organic Electrochemical Transistors for Yeast Sensing

Impedance-based biosensors for microbes, such as yeast and bacteria, have been widely used as an alternative to optical sensing techniques. Yet, impedance-based techniques require complex electronics and data processing that are difficult to implement. Ultrasensitive, drift-correcting electronic devices are needed for biological sensing in complex environments. Organic electrochemical transistors (OECTs) provide high signal amplification at low voltages, but most studies have focused extensively on semiconductor materials within the channels used as amplifiers. This study uses a number of interfacial electrochemical modifications to floating gate OECTs to create a universal platform for biological sensing focused on real-time monitoring of yeast concentrations as a proof-of-concept. Specifically, Y. lipolytica was selected as a model system, as it has been studied extensively for use within the oleochemical industry for production of biofuels and plastics. Real-time monitoring of the presence of these cells is needed for process control and storage in relatively complex environments. Using a combination of interfacial Faradaic mechanisms and reference and sample channel calibrations, a working range of 10³-10⁶ CFU/mL is established, with a sensitivity of ∼6% per decade. One key advantage is that the output response using the dual floating gate OECT platform in this device architecture is significantly simpler than the output from electrochemical impedance spectroscopy and can be used as a base platform for future real-time field biosensors.