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Flexible Electrode Arrays

First electrode arrays

Electrode requirements and design

In consultation with the project partners from KU Leuven and TTK, we designed flexible electrode arrays suited for the respective applications.

For the non-human primate experiments (KU Leuven), we designed several types of microelectrodes. The different designs an be categorized as comb-shaped arrays, where multiple needles with equal length are implanted all at once, and long needles, with up to 8 electrodes along the shaft. This last kind of electrodes has been specifically designed for the envisioned behavioural experiments, to also reach the part of the cortex that is located in the sulci.

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Close-up of array

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Array 1

Array 2

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Calcium imaging array

For the calcium imaging experiments (TTK), comb-shaped arrays were developed, tailored to the brain  size of the mice and the field of view of the two-photon imaging set-up. Further, the size of the electrodes is different (smaller) than for the non-human primates: 20×30 µm² vs 50×90 µm². Following images show the final fabricated probes (already validated  in vivo):

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Electrode fabrication

The fabrication process for the first electrode arrays continues on previous research efforts from ReVision Implant and KU Leuven. The fabrication steps of the probes are as depicted in the figure on the left (adapted from: www.doi.org/10.1088/1741-2552/ac98e2).

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Lifetime engineering

We have improved the lifetime of the insulation layer and the electrodes of our electrode arrays to over 10 years (and counting), surpassing the FDA minimum for neural implants.

These measurements were obtained in accelerated againg tests under constant stimulation, a much more strict test than aging in a passive, unused state as is usually done in literature.

We also have animal test data showing a lifetime of at least 2.5 years in vivo.

Current electrode array design

  • Stable, wafer-scale fabrication process

  • Ultra-flexible, as thin as a single brain cell

  • 100x smaller lesion than current clinical arrays

  • Patented design & insertion mechanism

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Insertability at required density

Wafer-scale fabrication process

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