Engineering reversible elasticity in ductile and brittle thin films supported by a plastic foil

Reversible deformation is a unique property of elastic materials. Here, we design and fabricate highly stretchable multilayered films by patterning Y-shaped motifs through films of non- elastic materials, e.g. plastics, metals, ceramics. By adjusting the geometry and density of the motif, as well as the thickness of the film(s), the effective spring constant of the engineered film(s) can be tuned. Three-dimensional bending of the patterned film(s) enables macroscopic stretchability and minimizes local film strain fields. The engineered films demonstrate no preferential direction of stretching and the proposed design is versatile. Furthermore our approach is compatible with thin-film processing. We demonstrate the Y-shaped motifs allow for the design of stretchable plastic foils coated with metallic and metal oxide conductors. We anticipate the patterned motifs can be scaled down to offer a wider range of elastic electronic materials to use in stretchable electronics and to create soft bioelectronics. (c) 2017 Elsevier Ltd. All rights reserved

Conducting polymer electrodes for auditory brainstem implants

The auditory brainstem implant (ABI) restores hearing in patients with damaged auditory nerves. One of the main ideas to improve the efficacy of ABIs is to increase spatial specificity of stimulation, in order to minimize extra-auditory side-effects and to maximize the tonotopy of stimulation. This study reports on the development of a microfabricated conformable electrode array with small (100 mm diameter) electrode sites. The latter are coated with a conducting polymer, PEDOT:PSS, to offer high charge injection properties and to safely stimulate the auditory system with small stimulation sites. We report on the design and fabrication of the polymer implant, and characterize the coatings in physiological conditions in vitro and under mechanical deformation. We characterize the coating electrochemically and during bending tests. We present a proof of principle experiment where the auditory system is efficiently activated by the flexible polymeric interface in a rat model in vivo. These results demonstrate the potential of using conducting polymer coatings on small electrode sites for electrochemically safe and efficient stimulation of the central auditory syste

Human cochlear nucleus on 7 tesla diffusion tensor imaging: insights into micro-anatomy and function for auditory brainstem implant surgery

OBJECTIVE: The cochlear nucleus (CN) is the target of the auditory brainstem implant (ABI). Most ABI candidates have Neurofibromatosis Type 2 (NF2) and distorted brainstem anatomy from bilateral vestibular schwannomas. The CN is difficult to characterize as routine structural MRI does not resolve detailed anatomy. We hypothesize that diffusion tensor imaging (DTI) enables both in vivo localization and quantitative measurements of CN morphology. STUDY DESIGN: We analyzed 7 Tesla (T) DTI images of 100 subjects (200 CN) and relevant anatomic structures using an MRI brainstem atlas with submillimetric (50 μm) resolution. SETTING: Tertiary referral center. PATIENTS: Young healthy normal hearing adults. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: Diffusion scalar measures such as fractional anisotropy (FA), mean diffusivity (MD), mode of anisotropy (Mode), principal eigenvectors of the CN, and the adjacent inferior cerebellar peduncle (ICP). RESULTS: The CN had a lamellar structure and ventral-dorsal fiber orientation and could be localized lateral to the inferior cerebellar peduncle (ICP). This fiber orientation was orthogonal to tracts of the adjacent ICP where the fibers run mainly caudal-rostrally. The CN had lower FA compared to the medial aspect of the ICP (0.44 ± 0.09 vs. 0.64 ± 0.08, p < 0.001). CONCLUSIONS: 7T DTI enables characterization of human CN morphology and neuronal substructure. An ABI array insertion vector directed more caudally would better correspond to the main fiber axis of CN. State-of-the-art DTI has implications for ABI preoperative planning and future image guidance-assisted placement of the electrode array

Auditory Brainstem Implants: Recent Progress and Future Perspectives

The auditory brainstem implant (ABI) was first developed nearly 40 years ago and provides auditory rehabilitation to patients who are deaf and ineligible for cochlear implant surgery due to abnormalities of the cochlea and cochlear nerve. The aims of the following review are to describe the history of the ABI and innovations leading up to the modern ABI system, as well as highlight areas of future development in implant design

Auditory Brainstem Implants: Recent Progress and Future Perspectives

The auditory brainstem implant (ABI) was first developed nearly 40 years ago and provides auditory rehabilitation to patients who are deaf and ineligible for cochlear implant surgery due to abnormalities of the cochlea and cochlear nerve. The aims of the following review are to describe the history of the ABI and innovations leading up to the modern ABI system, as well as highlight areas of future development in implant design

Stretchable cuff device

The invention features a cuff device comprising a support having a first end, a second end and an elongated body in between; connection means for electrical, magnetic and/or fluidic magnetic connection with external devices; at least one of i) an electrode and/or electronic component operatively connected with said connection means configured to electrically interface with a biological tissue and ii) a channel having an inlet, an outlet and an elongated body in between operatively connected with said connection means via said inlet and configured to fluidically interface with a biological tissue via said outlet; and at least one buckle configured to receive said first end and permit the sliding therein of said elongated body so to close and lock the cuff electrode device at desired positions, characterized in that said support is stretchable

Stretchable Electrodes for Neuroprosthetic Interfaces

We have developed a stretchable gold microelectrode array (MEA) that can withstand the torsion requirements needed for implantable neuroprosthetic interface applications. The array is composed of thin gold (sub-100 nm thick) electrodes on a soft, 120 mu m thick polydimethylsiloxane (PDMS) silicone substrate with a patterned encapsulation layer. The impedance of individual electrodes was measured as a function of extreme torsion applied to the device, and was found to be relatively stable in the 15-75 k Omega range (f = 1kHz), and remained stable after 1000 torsion cycles

Long-term functionality of a soft electrode array for epidural spinal cord stimulation in a minipig model

Long-term biointegration of man-made neural interfaces is influenced by the mechanical properties of the implant materials. Substantial experimental work currently aims at replacing conventional hard implant materials with soft alternatives that can favour a lower immune response. Here we assess the performance of a soft electrode array implanted in the spinal epidural space of a minipig model for a period of 6 months. The electrode array includes platinum-silicone electrode contacts and elastic thin-film gold interconnects embedded in silicone. In-vivo electrode impedance and voltage transients were monitored over time. Following implantation, epidural stimulation produced muscle-specific evoked potentials and visible muscle contractions. Over time, postoperative and stimulation induced changes in electrode impedance were observed. Such trends provide a basis for future technological improvements aiming at ensuring the stability of soft implantable electrodes for neural interfacing