Abstract
The combination of electrophysiology and optogenetics enables the exploration of how the brain operates down to a single neuron and its network activity. Neural probes are in vivo invasive devices that integrate sensors and stimulation sites to record and manipulate neuronal activity with high spatiotemporal resolution. State-of-the-art probes are limited by tradeoffs involving their lateral dimension, number of sensors, and ability to access independent stimulation sites. Here, we realize a highly scalable probe that features three-dimensional integration of small-footprint arrays of sensors and nanophotonic circuits to scale the density of sensors per cross-section by one order of magnitude with respect to state-of-the-art devices. For the first time, we overcome the spatial limit of the nanophotonic circuit by coupling only one waveguide to numerous optical ring resonators as passive nanophotonic switches. With this strategy, we achieve accurate on-demand light localization while avoiding spatially demanding bundles of waveguides and demonstrate the feasibility with a proof-of-concept device and its scalability towards high-resolution and low-damage neural optoelectrodes.
Highlights
Exploring the human brain has emerged within both academia and industry as a multidisciplinary challenge[1] aimed at understanding how information is processed and results in mental functions and behavior[2] as well as at gaining insight into diseases, such as Parkinson’s and other neurological disorders[3].Invasive in vivo devices such as Michigan probes[4] integrate a variety of sensors and stimulation sites that locally record and manipulate neural activity with high spatial and temporal resolution[5,6]
We show that our strategy, which integrates both arrays of sensors and nanophotonic circuits with embedded ring resonators, effectively combines various ideal features for optoelectrodes: implant size reduction, increases in the numbers of sensors and stimulation sites, and light localization without heat generation
Optoelectrode architecture Our probes integrate both arrays of sensors for neural activity readout and nanophotonic circuits for passive and on-demand stimulation of the areas of interest
Summary
Exploring the human brain has emerged within both academia and industry as a multidisciplinary challenge[1] aimed at understanding how information is processed and results in mental functions and behavior[2] as well as at gaining insight into diseases, such as Parkinson’s and other neurological disorders[3].Invasive in vivo devices such as Michigan probes[4] integrate a variety of sensors and stimulation sites that locally record and manipulate neural activity with high spatial (few μm) and temporal (sub-ms) resolution[5,6]. Arrays of electrodes record the neuron extracellular potentials and enable the triangulation of the neuron positions by measuring differences in signal timing and amplitude[7]; neural stimulation with electrodes results in interference with the electrophysiological recordings and cannot target specific types of neurons[8]. State-of-the-art probes integrate both arrays of electrodes and light sources to record neurons while optically stimulating them, implementing feedback loops with high spatiotemporal resolution[14,15,16] these probes aim at (i) recording signals from high numbers of neurons by integrating multiple sensors[15], (ii) optically stimulating specific neural populations or groups by delivering light to the location(s) of interest in a (iii) passive fashion—. Probes with μLEDs and Lanzio et al Microsystems & Nanoengineering (2021)7:40
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