Neural Implants Without Electronics: A Proof-of-Concept Study on a Human Skin Model.

Patrick Kiele,Thomas Stieglitz,Cristian Pasluosta,David Braig,Jakob Weis,Yara Baslan

doi:10.1109/ojemb.2020.2981254

Abstract

Objective: Chronic neural implants require energy and signal supply. The objective of this work was to evaluate a multichannel transcutaneous coupling approach in an ex vivo split-concept study, which minimizes the invasiveness of such an implant by externalizing the processing electronics. Methods: Herein, the experimental work focused on the transcutaneous energy and signal transmission. The performance was discussed with widely evaluated concepts of neural interfaces in the literature. Results: The performance of the transcutaneous coupling approach increased with higher channel count and higher electrode pitches. Electrical crosstalk among channels was present, but acceptable for the stimulation of peripheral nerves. Conclusions: Transcutaneous coupling with extracorporeal transmitting arrays and subcutaneous counterparts provide a promising alternative to the inductive concept particularly when a fully integration of the system in a prosthetic shaft is intended. The relocation of the electronics can potentially prevent pressure sores, improve accessibility for maintenance and increase lifetime of the implant.

Highlights

The integration of somatosensory feedback in upper and lower limb prostheses has been shown to help patients in performing daily tasks such as object manipulation or walking on uneven ground [1]–[3]
In this work, we focused on the evaluation of the coupling performance, since the stimulation paradigms of nerves has been already widely evaluated with different electrode designs [18]
The current picked-up at the different electrode distances presented a maximum at the direct path (Fig. 2c, 0 mm distance, 63.93 ± 10.25 μA, 70.00 ± 10.68 μA, 70.00 ± 10.68 μA and 65.95 ± 6.57 μA for skin sample 1 to 4, respectively), and decreased with increasing distance (Fig. 2c, 22.46 ± 7.69 μA, 22.46 ± 7.69 μA, 24.43 ± 0.57 μA and 32.79 ± 0.82 μA for skin sample 1 to 4, respectively)

Summary

Introduction

The integration of somatosensory feedback in upper and lower limb prostheses has been shown to help patients in performing daily tasks such as object manipulation or walking on uneven ground [1]–[3]. Somatosensory feedback is essential to restore the sense of embodiment and agency, and may reduce phantom limb pain [4]. Recent studies demonstrated that electrical stimulation of peripheral nerves is an excellent alternative to stimulating the sensorimotor cortex, reducing the invasiveness of the system while producing an almost-natural and selective sense of touch [1]. Different electrode designs exist to stimulate peripheral nerve pathways (e.g., TIME [5], TEENI [6], Cuff [7], LIFE [8], [9] and (Slanted [2]-SUEA) Utah electrode arrays-UEA [3]). Energy and signal supply is limited to percutaneous cabling or inductive coupling. Percutaneous cables penetrating the skin provide a relatively easy opportunity to interconnect implanted neural electrodes with an external stimulation device. A high risk of infection as well as skin irritation limit this approach to acute or short term treatments [10]–[13]

Methods

Results

Discussion

Conclusion