In Vitro Reconstruction of Axonal Heat Sensing with a Photothermal Nerve‐on‐a‐Chip

ABSTRACT Axons are the initial sites of thermal signal detection and transduction, but their localized response to heat remains poorly characterized. Here, we present a photothermal nerve‐on‐a‐chip platform that reconstructs in vitro the key elements of axonal thermosensation. By integrating graphene‐based photothermal heaters with microelectrode arrays inside axon‐guiding microchannels, the platform enables localized, millisecond‐scale thermal stimulation and simultaneous extracellular recording of action potentials. Using this platform, we uncovered rapid and reproducible heat‐evoked responses in rat dorsal root ganglion neurons, including thermoreceptor‐mediated rapid desensitization. With its ability to distinguish stimulus‐locked and inter‐pulse activity, we also observed distinct thermal‐response profiles in human iPSC‐derived sensory neurons, characterized by delayed heat responsiveness. Our platform enables high‐resolution analysis of axonal temperature coding and is a scalable tool for exploring peripheral thermosensation in development and disease.