Long termin vitrofunctional stability and recording longevity of fully integrated wireless neural interfaces based on the Utah Slant Electrode Array

Abstract

We evaluate the encapsulation and packaging reliability of fully integrated wireless neural interface based on Utah Slant Electrode Array/integrated neural interface-recording version 5 (USEA/INI-R5) system by monitoring the long term in-vitro functional stability and recording longevity. The integrated neural interface (INI) encapsulated with 6 μm Parylene-C was immersed in phosphate buffered saline (PBS) for a period of over 276 days (with the monitoring of the functional device still ongoing). The full functionality (wireless radio-frequency power, command and signal transmission) and the ability of the electrodes to record artificial neural signals even after 276 days of PBS soaking with little change (within 14%) in signal/noise amplitude constitutes a major milestone in long term stability, and allows to study and evaluate the encapsulation reliability, functional stability, and its potential usefulness for wireless neural interface for future chronic implants.

Serum protein layers on parylene-C and silicon oxide: Effect on cell adhesion

“…Parylene is applied on the desired surface via a chemical vapor deposition (CVD) process [4] . Recently, parylene has found numerous applications in bioengineering as an encapsulating material for medical implants [5] , a stencil to pattern cells [6] and a physical trap for cells [7] . The most frequently used derivative of the parylene family is parylene-C (poly-monochloro-para-xylylene), in which an aromatic hydrogen atom is replaced by a chlorine atom.…”

Non‐hermetic packaging of biomedical microsystems from a materials perspective: A review

“…The variation of the RF signal and the transmission frequency lies within 15% and 0.3% of the initial values, respectively. A wide range of neural interfacing devices utilizing non-hermetic packaging with surprising appealing in vitro accelerated lifetime test results have been reported (Lee et al, 2011), (Lecomte et al, 2017), (Jeong et al, 2012), (Bottausci et al, 2015;Kwon et al, 2015;Sharma et al, 2011). Parylene-C was selected as the outermost packaging layer for these devices because of the ability to form a conformal, pinhole-free coating on complicated topographies and its lower moisture permeability compared with PDMS and polyimide.…”

“…Reprinted with permission from Bottausci et al (2015). Copyright © 2015 IEEE F I G U R E 3 (a) Schematic and (b) photograph of the neural implant system described by Sharma et al (2011). This technique involves the placement of an expandable stent graft within the aorta (Kim, Yim, Kim, Kang, & Lee, 2019).…”

“…Reprinted with permission fromSharma et al (2011). Copyright © 2011 IOP Publishing F I G U R E 4 (a) Cross section of the implantable pressure sensor described by.…”

The development of neural stimulators: a review of preclinical safety and efficacy studies

“…The simplest evaluation of device stability consists of soaking the assembly passively in saline, preferably at body temperature or higher, over many months. This allows validation of the stability of the components or assemblies under a corrosive fluid environment (30, 36, 41).…”