Design and engineering of light-driven dynamic films for bioelectronic interfacing

Abstract: In the realm of neuroelectronics, the challenge lies in achieving finer observations of physiological processes to comprehend neuronal interactions and computations. This necessitates the development of more compliant and biomimetic interfaces for improved integration with biological tissues, enabling finer physiological process observations. Commonly used flat and static electrode interfaces contrast sharply with the dynamic, complex, and three dimensional (3D) extracellular matrix (ECM) in which cells reside. Introducing 3D patterns on electrode surfaces enhances cell-chip coupling, improving the signal recording. Moreover, inorganic electrodes are stiff and rigid, creating mechanical mismatches with softer biological tissues, and they fail to fully capture ionic conduction.This thesis addresses these challenges by focusing on designing and engineering a multi-layer dynamic and stimuli-responsive bioelectronic interface. The system combines light-responsive, deformable polymers like Poly(Disperse Red 1-methacrylate) (pDR1m) with conductive polymers such as Poly(3,4-ethylenedioxythiophene): poly(stirensulfonate) (PEDOT:PSS). pDR1m responds to light, exhibiting 3D surface topography deformation, while PEDOT:PSS facilitates electrical recording and stimulation of cells, offering mixed electronic and ionic conduction as well as good mechanical properties. The potential use of an intermediate Polydimethylsiloxane (PDMS) film to improve layer adhesion is also explored. The individual and multi-layer samples were first optimized for spin coating manufacturing, and then thoroughly characterized to investigate their thickness, morphology, optical and electrochemical properties. Patterning of pDR1m-based samples was carried out using laser scanning confocal microscopy and a Lloyd’s mirror interferometer.The pDR1m\PEDOT:PSS sample demonstrates promising morphological and conductive properties, and the presence of PEDOT:PSS does not alter the absorption spectra of pDR1m. The multi-layer approach also supports efficient inscription of 3D surface reliefs without damaging the conductive layer. In conclusion, this work successfully designs conductive and dynamic light-driven films, which showcase good potential for bioelectronics and neuroelectronic interfaces. These interfaces could lead to enhanced investigations into combined electromechanical stimulation on cells and provide a more biomimetic coupling with biological tissues.