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

Abstract

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.

Hybrid Bionic Nerve Interface for Application in Bionic Limbs

“…It was also biocompatible, [ 28 ] making it suitable for fabricating peripheral nerve interfaces. [ 29 ] Figure 2 a shows the fabricated SMP interface, which had two electrodes for making parallel contact with the nerve and two electrodes for making contact with the muscle graft. The fabricated SMP electrode was transparent, allowing visibility for surgery and using other types of measurement, such as imaging.…”

“…The interface was fabricated using a standard photolithography process, and further information about the fabrication process could be found in previous studies. [ 29 ] To fabricate the 1st SMP layer, the SMP solution was spin‐coated (800 rpm, 25 s) on a wafer coated with 1 µm of aluminum (Al). The SMP was polymerized for 30 min under UV radiation at a wavelength of 365 nm.…”

Shape Memory Hydrogels for Biomedical Applications

“…For this purpose, thiolene/acrylate-based SMHs were reported, which were further coated with iridium oxide (IrO 2 ) to improve electrochemical performances. The fabricated hydrogels were thermally programmed into a hook shape (50 • C and 0 • C) while undergoing shape morphing at 38 • C during in vivo nerve stimulation application [49]. programmed into a hook shape (50 °C and 0 °C) while undergoing shape morphing at 38 °C during in vivo nerve stimulation application [49].…”

A Microclip Peripheral Nerve Interface (μcPNI) for Bioelectronic Interfacing with Small Nerves

“…Self-bonding Sciatic nerve, rat 1000 Stimulation evoked, chronic recording (7wk), nerve-to-nerve interfacing Lienemann et al [18] Stretchable cuff electrode 2 PDMS 2 MPa Sciatic nerve, rat 1600 Conformable to nerve, stimulation evoked Cho et al [29] Double clip neural interface (DCNI) (Figure S2, Supporting Information). To facilitate the electrical connection to external test equipment, the contact pads on the sMEA were compression bonded to a connectorized PCB; silver paste was applied to the contact pads to ensure a low-impedance junction.…”

“…Conventional PNI technologies include cuff electrodes that envelop the nerve, [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] sieve electrodes that provide mechanical guidance for regenerating nerves, [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ] stiff penetrating arrays, [ 45 , 46 ] and flexible arrays designed to be inserted longitudinally [ 23 , 38 , 39 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ] or transverse to the direction of the fibers [ 48 , 49 ] ( Table 1 ). While there are distinct advantages to each of these approaches, none of them sufficiently addresses the biomechanical and environmental challenges required for long‐term reliable stimulation and recording.…”