Optical Recording of Bioelectric Signals using a Microscope Objective

Understanding electrical signals generated by biological cells is key to deciphering many biological phenomena. Noninvasive recording of these signals can be achieved by employing optical methods. However, existing optical methods, such as those that rely on fluorescent probes, suffer from photobleaching which can place limitations on the recording rate and recording duration. Electrochromic optical recording (ECORE) uses the electrochromism exhibited by certain materials, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), to record the electrical activity of cells. ECORE is noninvasive and also allows the experimenter the spatial flexibility to choose specific cells to record signals from. Integrating ECORE with microscopy would enable recording with higher spatial resolution and open up the technique to a broader community of researchers. In this work, we report on the development of a high-NA microscope objective-based ECORE. We demonstrate the recording of extracellular action potentials from cardiomyocytes with single-cell resolution and high sensitivity of <10 µV. The integration of ECORE with common microscopy setups opens the door to a broader implementation of ECORE and enables researchers to expand the recording of bioelectric signals to better understand the biological processes that are integral to life.