Organic electrochemical transistor arrays for multichannel electrophysiological recordings

Abstract

The emerging realms of bioelectronics have brought the advent of numerous therapeutic and diagnostic biomedical devices. One of the promising example of organic bioelectronics is the organic electrochemical transistors (OECTs). Although most of the attentions have been dedicated to the applications of microelectrode arrays and field-effect transistors during the past decades, OECT nevertheless offers an attractive high signal transducing capability and intrinsic flexible mechanical property, endowing it with great benefits in interfacing with biological milieu. Most of the biological sensing on OECT platforms, however, stayed at single-channel recording stage. Therefore the spatial dependence electrophysiological activities were rarely studied on OECT. This thesis shows an example on how to engineer multichannel OECT arrays into a versatile two-dimensional extracellular electrophysiology recording platform for mapping cardiac action potentials and screening for new drugs, as well as for monitoring the integrity of barrier tissues. In the first part of the study, a 16-channel OECT array sensing platform was established for measuring the cardiac action potential of varies cardiac cells including primary rat cardiomyocytes and cardiomyocytes from human pluripotent stem cells (hPSC-CMs). The speed and direction of the action potential propagation was calculated from a polynomial surface fitted from space-time coordinates. The action potential patterns of 2D cell monolayer and 3D microtissues displayed distinct features on OECT. Examples of drug testing was also demonstrated on OECT array by treating two chronotropic agents on cardiac tissues. The validation of a 64-channel OECT array for monitoring action potentials was demonstrated for the first time. In the second part, the 16-channel OECT array was utilized to monitor the invasive property of nasopharyngeal carcinoma on epithelial barriers. The harmonic transconductance-based sensing on OECT revealed the distinguishable transepithelial resistance of epithelial cells and cancer cells. Such a measurement on the 2D array furthermore illustrated the spatial distribution of cancer cells and epithelial cells in their co-culture. This thesis expanded the scopes of OECTs into a 2D biological environment, where the spatial dependent electrophysiological information was able to be sensed by the OECTs. This facilitates the further development of OECT array for pharmacological applications and fundamental studies.

Date of Award	2018
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology