Multimodal Neuroimaging Microtool for Infrared Optical Stimulation, Thermal Measurements and Recording of Neuronal Activity in the Deep Tissue

Infrared neural stimulation (INS) uses pulsed near-infrared light to generate highly controlled temperature transients in neurons, leading them to fire action potentials. Stimulation of the superficial layer of the intact brain has been presented, however, the stimulation of the deep neural tissue has larger potential in view of therapeutic use. To reveal the underlying mechanism of deep tissue stimulation properly, we present the design, the fabrication scheme and functional testing of a novel, multimodal microelectrode for future INS experiments. Three modalities—electrophysiological recording, thermal measurements and infrared waveguiding abil—were integrated based on silicon MEMS technology. Due to the advanced functionalities, a single probe is sufficient to determine safe stimulation parameters in vivo. As far as we know, this is the first multimodal microelectrode designed for INS studies in deep neural tissue. In this paper, the technology and results of chip-scale measurements are presented