Self-Closing Stretchable Cuff Electrodes for Peripheral Nerve Stimulation and Electromyographic Signal Recording

Abstract

The cuff electrode can be wrapped in the columnar or tubular biological tissue for physiological signal detection or stimulation regulation. The reliable and non-excessive interfaces between the electrode and complex tissue are critical. Here, we propose a self-closing stretchable cuff electrode, which is able to self-close onto the bundles of tissues after dropping water. The curliness is realized by the mechanical stress mismatch between different layers of the elastic substrate. The material of the substrate can be selected to match the modulus of the target tissue to achieve minimal constraint on the tissue. Moreover, the self-closing structure keeps the cuff electrode free from any extra mechanical locking structure. For in vivo testing, both sciatic nerve stimulation to drive muscles and electromyographic signal monitoring around a rat’s extensor digitorum longus for 1 month prove that our proposed electrode conforms well to the curved surface of biological tissue.

Challenges and Opportunities of Implantable Neural Interfaces: From Material, Electrochemical and Biological Perspectives

“…For instance, the stretchable cuff electrode developed by Yu et al presented an SNR of 9.57±0.77 dB after implantation for 24 days, implying outstanding signal acquisition performance. [59] Kleinfeld et al [22] estimated the size and density of microelectrode for recording electrical spikes from individual neurons, with the results supporting that requiring 250000 channels cm −2 to conform with the average neuron spacing of ≈20 μm. [45] Kaiju et al [66] implanted a 96-channel gold (Au)-based fMEA (with an inter-electrode distance of 700 μm and recording site area of 350 μm 2 , 11±7.5 kΩ at kHz) on the finger representation area in the somatosensory cortex of macaque monkey.…”

“…It exhibited 90% selective stimulation of the pig sciatic nerve in vivo, thus facilitating future selective peripheral neural interfaces. Yu et al [59] further proposed a novel self-closing stretchable cuff electrode by integrating with shape memory materials, which can realize self-wrapping around the nerve bundles triggered by water (Figure 3C). Notably, such a selfclosing structure can protect the electrode free from other extra mechanical locking structures.…”

“…Reproduced with permission. [ 59 ] Copyright 2023, American Chemical Society. D) Illustration of electric muscle stimulation directly powered by TENG.…”

“…presented an SNR of 9.57±0.77 dB after implantation for 24 days, implying outstanding signal acquisition performance. [ 59 ] Kleinfeld et al. [ 22 ] estimated the size and density of microelectrode for recording electrical spikes from individual neurons, with the results supporting that requiring 250000 channels cm −2 to conform with the average neuron spacing of ≈20 µm.…”

“…C) The self-closing stretchable cuff electrode from its flattened state to its curved state when triggered by water and the implantation state around a rat sciatic nerve. Reproduced with permission [59]. Copyright 2023, American Chemical Society.…”