Mixed Charge Transport in Conjugated Polymers and its Impact on Biosensor Performance

Organic mixed conductors and electrochemical phenomena at solid-liquid interfaces have garnered significant attention for applications in bioelectronics, electrochromics, energy storage/conversion, neuromorphic computing, and thermoelectrics. These devices operate in electrolytes that render ions mobile in the film, making the coupling between electronic and ionic charges crucial. A prime example of such devices is the organic electrochemical transistor (OECT), a transducer used commonly to monitor bioelectronic signals. In this talk, I will introduce the class of conjugated polymers that have been used in OECT channels and methods to benchmark their performance. In operando techniques reveal that the ions enter the polymeric channel hydrated and that the excess swelling of the material has a significant imapct on device characteristics, which can be traced back to changes in the overall structural order. I will then introduce OECT based platforms for pathogen detection and discuss how their performance is affected by the type of mixed conductors used in the channel. Our work highlights the importance of characterizing the properties of conjugated polymer films n their electrolyte swollen state for drawing conclusions related to materials properties/device performance, which has a tremendous impact on the performance of biosensors.