Understanding the firing patterns of neuronal networks in response to external sensory inputs and internal states is instrumental in deciphering neural codes in the brain. Traditional intracellular electrophysiology recording using patch clamp affords large signals but is highly invasive and has extremely low throughput. Extracellular recording using multielectrode arrays is noninvasive but can only record from neurons that happen to locate near the electrodes. Optical electrophysiology methods provide high spatial flexibility to record from user-selected cells. However, current methods of optical recording rely heavily on inserting voltage-sensitive fluorescent molecules into the cell membrane, which suffer from cell phototoxicity, limited signal-to-noise ratio and recording duration due to photobleaching. In this seminar, I will introduce a label-free optical electrophysiological method named ElectroChromic Optical REcording (ECORE) that fuses the high spatial flexibility and resolution of optical recording methods with the high temporal resolution and signal stability of electrode-based recording methods. Rather than detecting voltage-sensitive fluorescence, ECORE detects electrogenic cell action potentials through voltage-sensitive optical absorption of π-conjugated electrochromic polymers that are outside the cell. Hence, ECORE does not require the insertion of any fluorescent probes such that it is non-perturbative to cells and is not limited by photobleaching or phototoxicity. It also enables long-term electrophysiological recordings from user-selected cells. Moreover, by engineering the optics and materials, ECORE can reject recording noise and artifacts, and perform high-throughput multi-site recording.