BPS2026 – Optical detection of cell signals at polymer interfaces

Neurons encode information through electrical and chemical signals, while cardiomyocytes translate electrical activity into coordinated mechanical contraction. Understanding the fundamental electrophysiological processes in these electrogenic cells hinges on tools capable of capturing bioelectric, biochemical, and biomechanical signals with minimal perturbation. Traditional approaches such as electrodes or fluorescent reporters have significantly advanced our understanding of brain and heart functions, but can be constrained by invasiveness, phototoxicity, and limited throughput. To overcome these challenges, we introduce a label-free optical detection technique for cell signals using polymeric materials. Our approach leverages the tunable chemical and optical properties of conjugated polymer films to convert cell signals into optical readouts. In our recent study, we focused on bioelectric signals. Dioxythiophene-based conjugated polymers exhibit strong electrochromic contrast such that their optical absorbance changes with external voltages. Harnessing these materials together with an ultrasensitive optical detection system, we achieved a voltage detection sensitivity of ∼ 3.3 μV with sub-millisecond temporal resolution. We reliably recorded field potentials from isolated rat hearts, extracellular action potentials of stem cell-derived cardiomyocytes and rat hippocampal neurons to capture key electrophysiological processes including neuronal excitability and cardiac excitation-contraction coupling. Our label-free optical recording method not only matches the recording sensitivity of traditional electrode-based recording methods but also eliminates the constraints of electrode patterning or placement. Importantly, our method requires no fluorescent reporters to be introduced into the cells. This work highlights the significant potential of conjugated polymers for advancing bioelectric detection technologies. Moving forward, we will expand this platform to enable long-term, simultaneous monitoring of biochemical signals and mechanically coupled cellular responses by leveraging advances in materials and optical design. This approach will open a new window into how electrical, chemical, and mechanical signaling converges to regulate cellular network functions.