Multifunctional neural probe for synchronized monitoring multiple brain signals

In recent years, understanding complex neural networks has been recognized as a significant challenge in neuroscience, especially in developing advanced technologies that can effectively monitor and regulate neural activity, which places greater demands on in situ multi-type neural signal acquisition and stimulation in the brain. However, conventional neural interfaces struggle to acquire multi-modal, multi-channel, and high spatial resolution physiological signals or perform stimulation simultaneously. In this paper, a highly integrated multifunctional neural probe (MFNP) combining electrophysiological recording, optogenetic stimulation, and chemical detection functions is developed for precise monitoring of brain signals. The optogenetic stimulation was realized by integrating on-chip laser diode to a silicon nitride optical waveguide, and Iridium oxide (IrO_x) microelectrodes obtained outstanding electrophysiological recording and neurostimulation properties. Moreover, by incorporating the Ag/AgCl reference electrode into the probe, the size of implants was greatly reduced, minimizing the risk of damage to brain tissue, and achieving a long-term, stable, high-resolution pH sensing capability with the IrO_x film. Finally, the probe's effectiveness in acquiring spontaneous action potentials and local field potentials was verified by in vivo experiments in the hippocampal region of mice, showing its potential in signal acquisition and stimulation. The findings suggest that the developed neural probe shows significant potential for application in neural circuit research and clinical treatment.