Advanced Neural Interface toward Bioelectronic Medicine Enabled by Micro-Patterned Shape Memory Polymer

<jats:p>Recently, methods for the treatment of chronic diseases and disorders through the modulation of peripheral and autonomic nerves have been proposed. To investigate various treatment methods and results, experiments are being conducted on animals such as rabbits and rat. However the diameter of the targeted nerves is small (several hundred μm) and it is difficult to modulate small nerves. Therefore, a neural interface that is stable, easy to implant into small nerves, and is biocompatible is required. Here, to develop an advanced neural interface, a thiol-ene/acrylate-based shape memory polymer (SMP) was fabricated with a double clip design. This micro-patterned design is able to be implanted on a small branch of the sciatic nerve, as well as the parasympathetic pelvic nerve, using the shape memory effect (SME) near body temperature. Additionally, the IrO2 coated neural interface was implanted on the common peroneal nerve in order to perform electrical stimulation and electroneurography (ENG) recording. The results demonstrate that the proposed neural interface can be used for the modulation of the peripheral nerve, including the autonomic nerve, towards bioelectronic medicine.</jats:p>1

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3D printing fabrication process for fine control of microneedle shape

Microneedle electrode (ME) is used to monitor bioelectrical signals by penetrating via the skin, and it compensates for a limitation of surface electrodes. However, existing fabrication of ME have limited in controlling the shape of microneedles, which is directly relevant to the performance and durability of microneedles as an electrode. In this study, a novel method using 3D printing is developed to control needle bevel angles. By controlling the angle of printing direction, needle bevel angles are changed. Various angles of printing direction (0–90°) are investigated to fabricate moldings, and those moldings are used for microneedle fabrications using biocompatible polyimide (PI). The height implementation rate and aspect ratio are also investigated to optimize PI microneedles. The penetration test of the fabricated microneedles is conducted in porcine skin. The PI microneedle of 1000&nbsp;μm fabricated by the printing angle of 40° showed the bevel angle of 54.5°, which can penetrate the porcine skin. The result demonstrates that this suggested fabrication can be applied using various polymeric materials to optimize microneedle shape. © 2022, The Author(s).TRU

Recent progress on peripheral neural interface technology towards bioelectronic medicine.

10.1186/s42234-020-00059-zBioelectron Med6123

Triboelectric neurostimulator for physiological modulation of leg muscle

Neurostimulation using triboelectric nanogenerators (TENGs) has been actively researched. However, only limited neural responses have been demonstrated since the previous TENGs could not change stimululs parameters owing to limited operation design and conditions. To overcome these challenges, we report a rotation-based triboelectric neurostimulator (RoTENS) that allows the continuous modulation of stimulus parameters depending on rotation while generating a constant charge output. The RoTENS adjusts the stimulus parameters by controlling the rotational speed and non-contact method. The electrode materials and patterns were optimized, and the characterization of RoTENS was investigated. Furthermore, the neurophysiological validation of hindlimb modulation in rats was demonstrated. By directly stimulating the sciatic nerve branches using RoTENS, dorsiflexion (max. 13.12°) and plantar flexion (maximum 29.34°), which are major movements of the hindlimb for gait, were induced. Varying the frequency (10–50 Hz) allows the muscle to smoothly shift its physiological state from twitching to fused tetanus. The natural relaxation of the muscle is induced by changing the current amplitude via the height of the rotator (0–6 mm). These results indicate that RoTENS is sufficient to induce the desired physiological response while creating wide-ranging frequencies and amplitudes. We expect that RoTENS will open up new opportunities and possibilities for the use of TENG as neurostimulators. © 2022 The AuthorsTRU

Optimization of Motor-Based Rotational Triboelectric Nanogenerators (RoTENGs) for Neural Stimulation

This paper demonstrates optimization and demonstration of rotational TENGs (RoTENGs) for neural stimulation. The proposed RoTENGs generate electrical stimulation pulses by motor rotation. Two prototypes are investigated for this study. The generated pulse parameters can be modulated by changing the speed of the motor. The current and charge values of the pulses are also investigated for neurostimulation. Furthermore, neural stimulation of a sciatic nerve in rats using the proposed RoTENGs is demonstrated with monitoring muscle movement and with recording neural signals. The result indicates that this RoTENG could be used for neuromodulation applications such as neuroprosthetics and rehabilitation near future. © 2021 IEEE

Development of a Chemically Driven Biomimetic Modular Artificial Muscle (BiMAM)

Human skeletal muscle is widely considered to be the most efficient actuator, leading to extensive research on developing artificial muscles. Bioinspired technologies such as soft robotics and biomimetics are used to produce artificial muscles with performance characteristics similar to those of their biological counterpart. Despite the complexity of human skeletal muscle, advanced engineering materials and unique approaches can help develop an artificial muscle that replicates its kinematic motions. Herein, biomimetic modular artificial muscle (BiMAM), which is the culmination of different design strategies, is presented, and fabrication methods aimed at developing this BiMAM. This chemically driven modular artificial muscle uses shape memory alloy coated with nanomaterials and nano-catalysts. Herein, a high-energy density fuel is employed to actuate this artificial muscle, enabling fast and efficient outputs. Multiple performance characteristics are determined by conducting controlled experiments. Various methods are demonstrated to control the fuel-based valve system and the actuation of the chemically driven artificial muscle. Lastly, to evaluate its functionality, the curling movement of a robotic finger using BiMAM is demonstrated.TRU

Imperceptive and reusable dermal surface EMG for lower extremity neuro-prosthetic control and clinical assessment

Abstract Surface electromyography (sEMG) sensors play a critical role in diagnosing muscle conditions and enabling prosthetic device control, especially for lower extremity robotic legs. However, challenges arise when utilizing such sensors on residual limbs within a silicon liner worn by amputees, where dynamic pressure, narrow space, and perspiration can negatively affect sensor performance. Existing commercial sEMG sensors and newly developed sensors are unsuitable due to size and thickness, or susceptible to damage in this environment. In this paper, our sEMG sensors are tailored for amputees wearing sockets, prioritizing breathability, durability, and reliable recording performance. By employing porous PDMS and Silbione substrates, our design achieves exceptional permeability and adhesive properties. The serpentine electrode pattern and design are optimized to improve stretchability, durability, and effective contact area, resulting in a higher signal-to-noise ratio (SNR) than conventional electrodes. Notably, our proposed sensors wirelessly enable to control of a robotic leg for amputees, demonstrating its practical feasibility and expecting to drive forward neuro-prosthetic control in the clinical research field near future