Biology subjects

Gaspar, J.

Publications and source records attributed to Gaspar, J..

2 recordsLinked to original sources

bioRxiv2021

Hybrid multisite silicon neural probe with integrated flexible connector for interchangeable packaging

Multisite neural probes are a fundamental tool to study brain function. Hybrid silicon/polymer neural probes, in particular, allow the integration of complex probe geometries, such as multi-shank designs, with flexible biocompatible cabling. Despite these advantages and benefiting from the highly reproducible fabrication methods on both silicon and polymer substrates, they have not been widely available. This paper presents the development, fabrication, characterization, and in vivo electrophysiological assessment of a hybrid multisite multi-shank silicon probe with a monolithically integrated polyimide flexible interconnect cable. The fabrication process was optimized on wafer level and several neural probes with 64 gold electrode sites equally distributed along 8 shanks with an integrated 8 m-thick highly flexible polyimide interconnect cable were produce. To avoid the time-consuming bonding of the probe to definitive packaging, the flexible cable was designed to terminate in a connector pad that can mate with commercial zero-insertion force (ZIF) connectors for electronics interfacing. This allows great experimental flexibility since interchangeable packaging can be used according to experimental demands. High-density distributed in vivo electrophysiological recordings were obtained from the hybrid neural probes with low intrinsic noise and high signal-to-noise ratio (SNR).

bioengineering↗

bioRxiv2020

Double-layer flexible neuronal probe with closely spaced electrodes for high-density in vivo brain recordings

Flexible probes for brain activity recordings are an attractive emerging approach that reduces mechanical mismatch between probe and neuronal tissue, thus minimizing the risk of brain damage or glial scaring. Although promising, flexible probes still present some technical challenges namely: i) how to overcome probe buckling during brain insertion given its intrinsically low mechanical rigidity; ii) how to fabricate closely spaced electrode configurations for high density recordings by standard lithography techniques in the flexible substrate. Here, we present a new flexible probe based solely on standard and low-cost lithography processes, which has closely spaced 10 m diameter gold electrode sites on a polyimide substrate with inter-site distances of only 5 m. By using a double-layer design and fabrication approach we were able to accommodate closely spaced electrode sites at two different depths from probe surface while also providing additional stiffening, just sufficient to prevent probe buckling during brain insertion. Detailed probe characterization through metrology of structural and electrical properties and chemical composition analysis, as well as functional assessment through in vivo high-density recordings of neuronal activity in the mouse cortex, confirmed the viability of this new fabrication approach and that this probe can be used for obtaining high quality brain recordings with excellent signal-to-noise ratio (SNR).

bioengineering↗