A comparison of insertion methods for surgical placement of penetrating neural interfaces

Abstract

Many implantable electrode arrays exist for the purpose of stimulating or recording electrical activity in brain, spinal, or peripheral nerve tissue, however most of these devices are constructed from materials that are mechanically rigid. A growing body of evidence suggests that the chronic presence of these rigid probes in the neural tissue causes a significant immune response and glial encapsulation of the probes, which in turn leads to gradual increase in distance between the electrodes and surrounding neurons. In recording electrodes, the consequence is the loss of signal quality and, therefore, the inability to collect electrophysiological recordings long term. In stimulation electrodes, higher current injection is required to achieve a comparable response which can lead to tissue and electrode damage. To minimize the impact of the immune response, flexible neural probes constructed with softer materials have been developed. These flexible probes, however, are often not strong enough to be inserted on their own into the tissue, and instead fail via mechanical buckling of the shank under the force of insertion. Several strategies have been developed to allow the insertion of flexible probes while minimizing tissue damage. It is critical to keep these strategies in mind during probe design in order to ensure successful surgical placement. In this review, existing insertion strategies will be presented and evaluated with respect to surgical difficulty, immune response, ability to reach the target tissue, and overall limitations of the technique. Overall, the majority of these insertion techniques have only been evaluated for the insertion of a single probe and do not quantify the accuracy of probe placement. More work needs to be performed to evaluate and optimize insertion methods for accurate placement of devices and for devices with multiple probes.

Hybrid Bionic Nerve Interface for Application in Bionic Limbs

“…The formation of less fibrosis may contribute to high‐quality signal (high SNR) acquisition. [ 53–55 ] These histological examination results show that the bionic interface is successfully reinnervated with regenerated NMJs despite the implantation of the neural interface inside the RPNI. Additionally, it shows the superiority of the SMP used as a material for fabricating the neural interface for chronic transplantation.…”

High‐Conductivity Stoichiometric Titanium Nitride for Bioelectronics

“…The most critical component is the actual electrode interfacing with the physiological environment. [ 4 ] Various figures of merit are important for biointerface electrodes: electrochemical impedance, charge injection capacity, and finally the electrochemical passivity window, particularly the overpotential values for possibly harmful irreversible reactions. [ 5 ] Moreover, this electrode must fulfill the strictest requirements for stability.…”

Making a case for endovascular approaches for neural recording and stimulation

“…The most common electrodes for recording from or stimulating neural tissue are either placed in direct contact with or directly above the tissue (such as on the scalp or dura). Large, external electrodes, such as scalp electroencephalography (EEG) electrodes, are used to record electrical activity through the skin from large cortical areas, providing clinical insight into the overall health and function of different regions of the brain (see section 2.1) [3][4][5]. Smaller, implanted electrodes, such as electrocorticography (ECoG) and depth electrodes, can record from smaller cortical areas and subcortical areas respectively and give more localized information on the electrical activity in that region.…”

“…Smaller, implanted electrodes, such as electrocorticography (ECoG) and depth electrodes, can record from smaller cortical areas and subcortical areas respectively and give more localized information on the electrical activity in that region. In addition, these small electrodes can provide local stimulation to neural tissue, which is useful for the treatment of many neurologic disorders and the mapping of brain function (see sections 2.2 and 2.3) [3][4][5][6][7][8][9][10][11][12][13][14]. At an even smaller size, microelectrodes record and stimulate on a cellular level, delivering current to or recording from a small handful of cells at a time, and transmitting high resolution information to and from the tissue (see section 2.4) [3,5,13,14].…”