Single-Sided Multimodal Neural Probe Enabling Co-Localized Recording of Electrical and Chemical Signals

Abstract

Understanding the relationship between neural activity and neurochemical signaling is essential for investigating brain function and neurological disorders. Recent advances in multimodal neural probes enable the simultaneous monitoring of electrical and chemical brain signals; however, most platforms exhibit spatial and temporal mismatches between recording and sensing sites due to fabrication constraints. We present a single-sided multimodal neural probe that integrates chemical-sensing and neural-recording electrodes in close proximity. Using a sequential laser-induced graphene process on a flexible polyimide substrate, we fabricate distinct functional electrodes without photolithography or multilayer alignment. Glucose oxidase and black platinum functionalizations provide specific chemical and electrical sensing capabilities. The probe achieves reliable in vitro glucose detection, showing stable, concentration-dependent responses within physiologically relevant ranges and high selectivity. The black platinum-coated recording electrode exhibits low impedance and strong signal fidelity, making it suitable for extracellular spike recording. In vivo experiments validate the probe by enabling real-time tracking of glucose dynamics and simultaneous neural spike acquisition in the mouse hippocampus' CA3 region. This fabrication strategy improves spatial resolution in multimodal neural interfacing-enabling precise temporal correlation between electrical and chemical signals by minimizing diffusion delays-providing a valuable tool for investigating dynamic neurochemical and electrophysiological processes in the brain.