Microneedle cuff electrodes for extrafascicular peripheral nerve interfacing.

OBJECTIVE: The work presented here describes a new tool for peripheral nerve interfacing, called the microneedle cuff (µN-cuff) electrode. APPROACH: µN arrays are designed and integrated into cuff electrodes for penetrating superficial tissues while remaining non-invasive to delicate axonal tracts. MAIN RESULTS: In acute testing, the presence of 75 µm height µNs decreased the electrode-tissue interface impedance by 0.34 kΩ, resulting in a 0.9 mA reduction in functional stimulation thresholds and increased the signal-to-noise ratio by 9.1 dB compared to standard (needle-less) nerve cuff electrodes. Preliminary acute characterization suggests that µN-cuff electrodes provide the stability and ease of use of standard cuff electrodes while enhancing electrical interfacing characteristics. SIGNIFICANCE: The ability to stimulate, block, and record peripheral nerve activity with greater specificity, resolution, and fidelity can enable more precise spatiotemporal control and measurement of neural circuits.

Computational Field Shaping for Deep Brain Stimulation With Thousands of Contacts in a Novel Electrode Geometry.

OBJECTIVE: Deep brain stimulation (DBS) alleviates symptoms associated with some neurological disorders by stimulating specific deep brain targets. However, incomplete stimulation of the target region can provide suboptimal therapy, and spread of stimulation to tissue outside the target can generate side-effects. Existing DBS electrodes generate stimulation profiles that are roughly spherical, neither matching nor enabling the mapping of therapeutic targets. We present a novel electrode design and will perform computational modeling of the new design to investigate its use as a next generation DBS electrode. MATERIALS AND METHODS: Computational simulations of a finite element model are performed for both the novel electrode and for a commercially available DBS electrode. RESULTS: Computational modeling results show that this new electrode design is able to steer stimulation radially around the device, creating voltage distributions that may more closely match deep brain targets. CONCLUSION: The ability to better match the anatomy and compensate for targeting errors during implantation will enable strict localization of the generated stimulation fields to within target tissues, potentially providing more complete symptom alleviation while reducing the occurrence of side-effects.

Fabrication and initial testing of the µDBS: a novel Deep Brain Stimulation electrode with thousands of individually controllable contacts.

High frequency electrical stimulation of deep brain structures such as the subthalamic nucleus in Parkinson's disease or thalamus for essential tremor is used clinically to reduce symptom severity. Deep brain stimulation activates neurons in specific brain structures and connection pathways, overriding aberrant neural activity associated with symptoms. While optimal deep brain stimulation might activate a particular neural structure precisely, existing deep brain stimulation can only generate roughly-spherical regions of activation that do not overlap with any target anatomy. Additionally, side effects linked to stimulation may be the result of limited control over placement of stimulation and its subsequent spread out of optimal target boundaries. We propose a novel lead with thousands of individually controllable contacts capable of asymmetric stimulation profiles. Here we outline the design motivation, manufacturing process, and initial testing of this new electrode design, placing it on track for further directional stimulation studies.