CPOS Seminar: Optical tracking of mixed charge transport in conducting polymers
Speaker: SCOTT T. KEENE, PhD, Electrical Engineering Division, Department of Engineering, and Department of Physics, University of Cambridge, UK
Abstract: Organic mixed ionic electronic conductors (OMIECs) have recently risen as a promising material choice for bioelectronic devices due to their low impedance, soft mechanical properties, and ability to transduce ionic signals to electronic currents. The unique behaviour of OMIECs arises from ion intercalation through the bulk of the material which can modify the oxidation state, and therefore charge carrier concentration, of the conjugated polymer backbone. The first part of this talk will discuss how OMIECs can be used in organic electrochemical transistors (OECTs) to amplify signals from electrochemical aptamer-based biosensors (EABs). EABs utilize the change in reaction kinetics of a redox probe due to a conformational change upon binding with the target analyte. To detect this change in kinetics, we operate OECTs with AC waveforms at the gate electrode rather than using typical DC gate potentials, allowing miniaturization of the sensor footprint without a corresponding decrease in output current. The second part of the talk will introduce an optical operando microscopy technique which provides insights for ionic and electronic transport in OMIECs. We use this technique to quantify internal fields and compare a variety of OMIECs during electrochemical (de)doping. The results help resolve the dynamics of electrochemical doping in OMIECs, providing guidance for device design as well as optimizing materials for improved performance in bioelectronic devices.
Bio: Scott received his B.S. in Materials Science and Engineering from the University of Washington in 2015. In 2020, he received his Ph.D. in Materials Science and Engineering from Stanford University where he worked in Prof. Alberto Salleo’s group as a Stanford Graduate Fellow. During his doctoral training, Scott developed wearable biosensors for detection of analytes in sweat as well as organic neuromorphic devices for artificial neural network accelerators and neural interfacing. He is currently a Marie Skłodowska Curie Actions Postdoctoral Fellow at the University of Cambridge working in the Department of Electrical Engineering and the Department of Physics under the Supervision of Prof. George Malliaras and Prof. Akshay Rao. His current research focuses on understanding the underlying physics of electrochemical doping in organic mixed ionic-electronic conductors.
