Q-PINE: A quick to implant peripheral intraneural electrode

Abstract

Objective. The implantation of intraneural electrodes in amputees has been observed to be effective in providing subjects with sensory feedback. However, this implantation is challenging and time consuming. Surgeons must be especially trained to execute the implantation. Therefore, we aimed at developing a novel peripheral intraneural electrode and insertion mechanism, which could drastically reduce the overall implantation time while achieving a high neural selectivity. Approach.A new insertion method based on hollow microneedles was developed to realize the prompt and effective simultaneous implantation of up to 14 active sites in a transversal manner. Each needle guided two Pt/Ir microwires through the nervous tissue. After the insertion, the microneedles were released, leaving behind the microwires. Each microwire had one active site, which was coated with poly-3,4-ethylenedioxythiophene (PEDOT) to enhance the electrochemical properties. The active sites were characterized by evaluating the impedance, charge storage capacity, and maximum injectable charge. Twelve quick to implant peripheral intraneural electrodes (Q-PINEs) were implanted in four pig sciatic nerves to evaluate the implantation time and neural selectivity. We compared the stimulation of the sciatic nerve with that of its branches. Main results. The average surgical access time was 23 min. The insertion time for 12 electrodes was 6.7 min (std. ±1.6 min). The overall implantation time was reduced by 40.3 min compared to the previously reported values. The Q-PINE system demonstrated a satisfactory performance during in vitro and in vivo characterization. The electrochemical results showed that the PEDOT coating successfully increased the electrochemical parameters of the active sites. Significance. With an average impedance of 1.7 kΩ, a maximum charge level of 76.2 nC could be achieved per active site. EMG recruitment curves showed that 46% of the active sites exhibited selective stimulation of four out of six muscles. The histological analysis indicated that the microwires successfully penetrated the nerve and single fascicles.

Multifaceted understanding of human nerve implants to design optimized electrodes for bioelectronics

“…Also the use of transcutaneous cables can induce risky infections or cable failures [9]. For these reasons, the development of a single intraneural electrode, fast-to-implant, with a comparable stimulation selectivity [61] part of a fully-implantable system is the next step for increasing adoption. Secondly, as demonstrated, the growth of fibrotic tissue is the cause of thresholds changes and nervous fibers activated that strongly influence the effectiveness of the neurostimulation.…”

A finite element model of the mechanical interactions between peripheral nerves and intrafascicular implants

“…This could also enable the study of any possible correlation between simulation results and measured scar size and shape, a feature that could improve accuracy in reducing the FBR in future models. The method could be used also to optimize the design of different implant formats, such cuffs [52,67], penetrating implants such as the longitudinal intrafascicular electrodes and others [10,[68][69][70]. Our study shows how mechanical FEM could facilitate the design of more effective and usable PNIs (similarly to electrical models [38]) and contributes a new tool for implant design optimization.…”

Methods of poly(3,4)-ethylenedioxithiophene (PEDOT) electrodeposition on metal electrodes for neural stimulation and recording

“…Increasing coating thickness and roughness with increased deposition charge density explain increases in CSC. In contrast to Pt CSC by pseudocapacity of 294 µC cm −2 (Merrill et al 2005), and Pt CSC observations ranging from 150 µC cm −2 to 5.6 mC cm −2 depending upon CV parameters (Harris et al 2018), CSC can be increased by PEDOT coating: 4.3× (Strauss et al 2020); 8.6× (Ouyang et al 2017); and 15× (Venkatraman et al 2011) in example studies. Deposition materials or methods which change PEDOT coating morphology also affect the CSC, such as acetonitrile solvent which increases roughness, real electrode area, and thus increases CSC (Bodart et al 2019).…”