Label-free optical detection of cellular action potentials using electrochromic materials

Advancing tools to record action potentials from cells is fundamental to understanding memory formation as well as cardiac and neurological disorders such as heart arrhythmias and Parkinson's disease. While optical-based recording methods using fluorescent proteins and dyes offer exceptional ability to detect action potentials from desired cells, these methods may be limited by phototoxicity or photobleaching. Previously, we have demonstrated the ability of label-free electrochromic optical recording (ECORE) to record action potentials from cells by using electrochromic materials such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which change color when electrical potentials are applied. This label-free method is non-invasive to cells and provides high spatial flexibility in detecting cell electrical signals while at the same time enabling long-term recordings. Here, we report on an ECORE with higher spatial resolution using smaller optics and shorter focal lengths and demonstrate its ability to record from single cells and from localized areas within cells.