State-of-the-art MEMS and microsystem tools for brain research

Abstract

Mapping brain activity has received growing worldwide interest because it is expected to improve disease treatment and allow for the development of important neuromorphic computational methods. MEMS and microsystems are expected to continue to offer new and exciting solutions to meet the need for high-density, high-fidelity neural interfaces. Herein, the state-of-the-art in recording and stimulation tools for brain research is reviewed, and some of the most significant technology trends shaping the field of neurotechnology are discussed.

Glial responses to implanted electrodes in the brain

“…Monitoring the electrical activity of large numbers of neurons simultaneously with single-cell resolution is an ongoing challenge in neural engineering 147 , and has motivated the design of increasingly high-density electrode arrays with smaller individual electrode site sizes 147 . Furthermore, as neuromodulation strategies become increasingly sophisticated (as exemplified by closed-loop systems), multiple implants within a single patient or research subject are becoming more common 148 .…”

Multi-shanks SiNAPS Active Pixel Sensor CMOS probe: 1024 simultaneously recording channels for high-density intracortical brain mapping

“…These include Neuropixels (Jun et al (2017b)), Neuroseeker (Raducanu et al (2016)) and, our own SiNAPS solution (Angotzi et al (2019)). Among these options, SiNAPS probes are the only devices that overcome the major scaling bottleneck caused by the spatial limits of analog front-ends (Seymour et al (2017)), thus allowing on-probe multiplexing of thousands of electrode signals on a few output lines. This approach has tremendous scaling potential: by increasing the number of recording electrodes while minimizing overall probe size, particularly the base area, SiNAPS is also a very promising solution for chronic experiments in animals, especially small animals like mice.…”

“…Recent studies (Jun et al (2017b); Raducanu et al (2016);De Dorigo et al (2018); Angotzi et al (2019)) proposed micro-/nano fabricated implantable Complementary Metal-Oxide Semiconductor (CMOS) probes with hundreds to thousands recordings sites within small cross-sectional areas. By integrating into the same silicon substrate electrodes and active electronic circuits for signal amplification and filtering, such implantable CMOS probes can simultaneously record from multiple brain regions (Seymour et al (2017); Steinmetz et al (2018)) with an unprecedented spatial resolution. Furthermore, the high 2D spatial resolution of these probes also permits the use of advanced automated sorting algorithms to better isolate putative single-unit activity, by exploiting correlations of individual neuron's spikes measured by closely and regularly spaced electrode contacts (Hilgen et al (2017); Jun et al (2017a);Yger et al (2018)).…”

SpikeForest: reproducible web-facing ground-truth validation of automated neural spike sorters

“…Direct electrical recording of extracellular potentials (Buzsáki, 2004;Seymour et al, 2017) is one of the most popular modalities for studying neural activity since it is possible to determine, with sub-millisecond time resolution, individual firing events from hundreds (potentially thousands) of cells, and to track the activity of individual neurons over hours or days. Recordings are acquired either from within the living animal (in vivo) or from extracted tissue (ex vivo), at electrodes separated by typically 5-25 µm, with sensitivities of order 10 µV, and 10-30 kHz sampling rate.…”