Bioelectrical Interfaces using Neural Slurries (BINS)

Project: Research project

Description

Summary - We will investigate the potential for an innovative, high-density, remotely activated neurostimulation interface for peripheral nerve that employs a particle-liquid (slurry) type of piezoelectric energy transducer injected into a nerve. It is dispersed whereby fine micron-sized particles generate stimulating currents are locally actuated at the fascicular level by ultrasound emitters either on the body surface, or near the nerve, or possibly in-between. This technology is directed to next-generation minimally-invasive neural interfaces to enable interaction with the neurophysiology of interest at high spatiotemporal resolution, precision, and specificity.
We have found that a simple system consisting of a millimeter-order piezoelectric chip mated to a small diode when placed near a nerve can evoke action events when illuminated by a remote source of ultrasound energy 1-4. Such a system can be made exceedingly compact due to the relatively good efficiency of piezoelectric materials and the high energy densities carried by ultrasound. Fine particle liquid slurry of piezoelectric ceramic and tens-of-micron-order scale semiconductor diodes create locally rectified dipolar electrical currents when illuminated by ultrasound beam passing through it. This can create stimulating current dipoles over theoretically tens of micron-order scales. This is a type of liquid bioelectric neurostimulator. Pilot data from our lab shows that ultrasound microbeams actuate small piezoelectric particles to produce electrical currents that are in the order of several tens to hundreds of microamperes after rectification and therefore sufficient to individually drive nerve fascicles. This approach addresses the difficult problem of scaling up the channel count of neurostimulation interfaces at increasingly finer electrical resolution while performing wirelessly for the peripheral and central nervous system. Although electrical wires to peripheral nerve surface electrodes work reasonably well at the level of stimulating whole nerve bundles, at higher channel numbers penetrating needle electrodes start to become a hazard when wiring pulls on neural electrode platforms with patient motion. Electrodes that are wirelessly free-floating within the nerve itself are not as affected by such forces because they move with the nerve.
The randomness of the dispersed piezoelectric powders in their orientation and position insures that at any given distribution organization there are some that are aligned to both the ultrasound beam and the detection electrodes. Pilot data from our lab indicates that random orientation of piezo-electric elements and Schottky diodes produce consistent voltage outputs. Trials with PZT powders introduced into the frog sciatic nerve suggest that they more easily disperse in distributed clusters rather than uniformly. How best to distribute them is still a matter of research. The proposed injectable slurry type neural interface will enable interaction with the neurophysiology of interest at unmatched spatiotemporal resolution, precision, and specificity. Combined with our understanding of neurophysiological mechanisms, it will enable the development of novel neuromodulation treatments that will be tuned automatically and continuously to the unique physiology of each individual and will produce no off-target effects. The proposed phase 1 of the work that will demonstrate proof of concept in bench-top and in vivo models will cost $258K (direct and indirect) over one year.
StatusFinished
Effective start/end date5/24/1611/23/17

Funding

  • DOD-DARPA: Biological Technologies Office (BTO): $262,350.00

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slurries
nerves
neurophysiology
electrodes
peripheral nervous system
liquids
diodes
frogs
central nervous system
semiconductor diodes
physiology
wiring
microbeams
piezoelectric ceramics
rectification
Schottky diodes
needles
floating
hazards
seats