High-density electrical and optical probes for neural readout and light focusing in deep brain tissue

Abstract

To advance neuroscience in vivo experiments, it is necessary to probe a high density of neurons in neural networks with single-cell resolution and be able to simultaneously use different techniques, such as electrophysiological recordings and optogenetic intervention, while minimizing brain tissue damage. We first fabricate electrical neural probes with a high density of electrodes and small tip profile (cross section of shank: 47-μm width × 16-μm thickness). Then, with similar substrate and fabrication techniques, we separately fabricate optical neural probes. We finally indicate a fabrication method that may allow integrating the two functionalities into the same device. High-density electrical probes have been fabricated with 64 pads. Interconnections to deliver the signal are 120-nm wide, and the pads are 5 × 25 μm. Separate optical probes with similar shank dimensions with silicon dioxide and silicon nitride ridge single-mode waveguides have also been fabricated. The waveguide core cross section is 250 nm × 160 nm. Light is focused above the waveguide plane in 2.35-μm diameter spots. The actual probes present two output focusing gratings on the shank.

Small footprint optoelectrodes using ring resonators for passive light localization

“…The nanophotonic circuit (Fig. 2a) consists of a bus waveguide, several ring resonators (which we place along the length of the tip at an optimized distance from the bus), and, for each ring, an output waveguide terminated by a grating 34 . When the input laser light from the bus matches the ring resonance frequency, which, for a given material and thickness, is mainly a function of the radius, the light resonates due to constructive interference and transfers to the output waveguide, where it is extracted by the grating.…”

The Future of Neuroscience: Flexible and Wireless Implantable Neural Electronics

“…[305] The final component of the implantable system is the connector which allows a cable to interface with an external computer. Three common options for these connectors include zero insertion force (ZIF) connectors, [177,306,307] which may be combined with polymer probes; or rigid alternatives such as Omnetics [110,233] or Samtec [308,309] connectors.…”

Implantable photonic neural probes for light-sheet fluorescence brain imaging

“…Optimization of the GC emitter design may reduce the sheet thickness of the neural probes and correspondingly increase the achievable image contrast. One potential approach is to implement a non-uniform GC design wherein the GC periods are selected to enable focusing 40 along the thickness-axis of the light sheet.…”