scholarly journals A Suprachoroidal Electrical Retinal Stimulator Design for Long-Term Animal Experiments and In Vivo Assessment of Its Feasibility and Biocompatibility in Rabbits

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
J. A. Zhou ◽  
S. J. Woo ◽  
S. I. Park ◽  
E. T. Kim ◽  
J. M. Seo ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Animal Experiments ◽  
Electrode Array ◽  
Rf Coil ◽  
Stimulation Mode ◽  
Retinal Stimulation ◽  
Implantable Stimulator ◽  
External Component

This article reports on a retinal stimulation system for long-term use in animal electrical stimulation experiments. The presented system consisted of an implantable stimulator which provided continuous electrical stimulation, and an external component which provided preset stimulation patterns and power to the implanted stimulator via a paired radio frequency (RF) coil. A rechargeable internal battery and a parameter memory component were introduced to the implanted retinal stimulator. As a result, the external component was not necessary during the stimulation mode. The inductive coil pair was used to pass the parameter data and to recharge the battery. A switch circuit was used to separate the stimulation mode from the battery recharging mode. The implantable stimulator was implemented with IC chips and the electronics, except for the stimulation electrodes, were hermetically packaged in a biocompatible metal case. A polyimide-based gold electrode array was used. Surgical implantation into rabbits was performed to verify the functionality and safety of this newly designed system. The electrodes were implanted in the suprachoroidal space. Evoked cortical potentials were recorded during electrical stimulation of the retina. Long-term follow-up using OCT showed no chorioretinal abnormality after implantation of the electrodes.

scholarly journals A mm-Sized Free-Floating Wireless Implantable Opto-Electro Stimulation Device

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 621
Author(s):  
Yaoyao Jia ◽  
Yan Gong ◽  
Arthur Weber ◽  
Wen Li ◽  
Maysam Ghovanloo
Keyword(s):  
Electrical Stimulation ◽  
Large Scale ◽  
Electrode Array ◽  
Cmos Process ◽  
Optical Stimulation ◽  
In Vivo Experiments ◽  
Stimulation Mode ◽  
Shift Keying ◽  
On Chip

Towards a distributed neural interface, consisting of multiple miniaturized implants, for interfacing with large-scale neuronal ensembles over large brain areas, this paper presents a mm-sized free-floating wirelessly-powered implantable opto-electro stimulation (FF-WIOS2) device equipped with 16-ch optical and 4-ch electrical stimulation for reconfigurable neuromodulation. The FF-WIOS2 is wirelessly powered and controlled through a 3-coil inductive link at 60 MHz. The FF-WIOS2 receives stimulation parameters via on-off keying (OOK) while sending its rectified voltage information to an external headstage for closed-loop power control (CLPC) via load-shift-keying (LSK). The FF-WIOS2 system-on-chip (SoC), fabricated in a 0.35-µm standard CMOS process, employs switched-capacitor-based stimulation (SCS) architecture to provide large instantaneous current needed for surpassing the optical stimulation threshold. The SCS charger charges an off-chip capacitor up to 5 V at 37% efficiency. At the onset of stimulation, the capacitor delivers charge with peak current in 1.7–12 mA range to a micro-LED (µLED) array for optical stimulation or 100–700 μA range to a micro-electrode array (MEA) for biphasic electrical stimulation. Active and passive charge balancing circuits are activated in electrical stimulation mode to ensure stimulation safety. In vivo experiments conducted on three anesthetized rats verified the efficacy of the two stimulation mechanisms. The proposed FF-WIOS2 is potentially a reconfigurable tool for performing untethered neuromodulation.

Enhancement by vasopressin of adrenergic responses in human mesenteric arteries

1997 ◽  
Vol 272 (3) ◽  
pp. H1087-H1093 ◽  
Author(s):  
P. Medina ◽  
I. Noguera ◽  
M. Aldasoro ◽  
J. M. Vila ◽  
B. Flor ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Animal Experiments ◽  
Mesenteric Arteries ◽  
Organ Bath ◽  
Adrenergic Stimulation ◽  
Response Curves ◽  
Receptor Stimulation ◽  
Half Maximal Effective Concentration

Vasopressin not only acts directly on blood vessels through V1-receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vitro and in vivo. The aim of the present study was to investigate whether subpressor concentrations of vasopressin could modify the constrictor responses to norepinephrine and electrical stimulation of the perivascular nerves in human mesenteric arteries. Human mesenteric artery rings (3-3.5 mm long, 0.8-1.2 mm OD) were obtained from 38 patients undergoing abdominal operations. The arterial rings were suspended in organ bath chambers for isometric recording of tension. Vasopressin (3 x 10(-11) M) enhanced the contractions elicited by electrical stimulation at 2, 4, and 8 Hz (by 100, 100, and 72%, respectively) and produced a leftward shift of the concentration-response curves to norepinephrine (half-maximal effective concentration decreased from 2.2 x 10(-6) to 5.0 x 10(-7) M; P < 0.05) without any alteration in maximal contractions. Vasopressin also potentiated KCl- and calcium-induced contractions. The V1-receptor antagonist 1-[beta-mercapto-beta,beta-cyclopentamethylenepropionic acid-2-O-methyl-tyrosine, 8-arginine]vasopressin (10(-6) M) prevented the potentiation evoked by vasopressin in all cases. The calcium antagonist nifedipine (10(-6) M) did not affect the potentiation of electrical stimulation and norepinephrine induced by vasopressin but abolished KCl-induced contractions. The results suggest that vasopressin, in addition to its direct vasoconstrictor effect, strongly potentiates the responses to adrenergic stimulation and KCl depolarization. Both the direct and indirect effects of vasopressin appear to be mediated by V1-receptor stimulation. The amplifying effect of vasopressin on constrictor responses may be relevant in those clinical situations characterized by increased plasma vasopressin levels.

scholarly journals Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Dong-Wook Park ◽  
Amelia A. Schendel ◽  
Solomon Mikael ◽  
Sarah K. Brodnick ◽  
Thomas J. Richner ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Electrode Array ◽  
Electrode Arrays ◽  
Neural Imaging ◽  
Brain Surface ◽  
Array Technology ◽  
Micro Electrode Arrays ◽  
The Brain

Abstract Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and compliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at >90% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications.

scholarly journals Effect of long-term caloric restriction and exercise on muscle bioenergetics and force development in rats

1999 ◽  
Vol 276 (4) ◽  
pp. E766-E773 ◽  
Author(s):  
Alena Horská ◽  
Larry J. Brant ◽  
Donald K. Ingram ◽  
Richard G. Hansford ◽  
George S. Roth ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Caloric Restriction ◽  
Citrate Synthase ◽  
Wheel Running ◽  
Control Group ◽  
Exercise Interventions ◽  
Ad Libitum ◽  
Second Period

We evaluated the hypothesis that long-term caloric restriction and exercise would have beneficial effects on muscle bioenergetics and performance in the rat. By themselves, each of these interventions is known to increase longevity, and bioenergetic improvements are thought to be important in this phenomenon. Accordingly, we investigated rats that underwent long-term caloric restriction and were sedentary, ad libitum-fed rats permitted to exercise by daily spontaneous wheel running (AE), and the combination of the dietary and exercise interventions (RE). Ad libitum-fed, sedentary rats comprised the control group.31P NMR spectra of the gastrocnemius muscle (GM) were collected in vivo at rest and during two periods of electrical stimulation. Neither caloric restriction nor exercise affected the ratio of phosphocreatine to ATP or pH at rest. During the first stimulation and after recovery, the RE group had a significantly smaller decline in pH than did the other groups ( P < 0.05). During the second period of stimulation, the decrease in pH was much smaller in all groups than during the first stimulation, with no differences observed among the groups. The combination of caloric restriction and exercise resulted in a significant attenuation in the decline in developed force during the second period of stimulation ( P < 0.05). A biochemical correlate of this was a significantly higher concentration of citrate synthase in the GM samples from the RE rats (32.7 ± 5.4 μmol ⋅ min−1 ⋅ g−1) compared with the AE rats (17.6 ± 5.7 μmol ⋅ min−1 ⋅ g−1; P < 0.05). Our experiments thus demonstrated a synergistic effect of long-term caloric restriction and free exercise on muscle bioenergetics during electrical stimulation.

scholarly journals Electrophysiological investigation of intact retina with soft printed organic neural interface

2021 ◽  
Author(s):  
Ieva Vebraite-Adereth ◽  
Moshe David-Pur ◽  
David Rand ◽  
Eric Glowacki ◽  
Yael Hanein
Keyword(s):  
Electrical Stimulation ◽  
Ex Vivo ◽  
Electrode Array ◽  
Carbon Electrodes ◽  
Natural Image ◽  
Neural Firing ◽  
Electrode Arrays ◽  
Electrical Recording ◽  
Research Activities

Abstract Objective. Understanding how the retina converts a natural image or an electrically stimulated one into neural firing patterns is the focus of on-going research activities. Ex vivo, the retina can be readily investigated using multi electrode arrays. However, multi electrode array recording and stimulation from an intact retina (in the eye) has been so far insufficient. Approach. In the present study, we report new soft carbon electrode arrays suitable for recording and stimulating neural activity in an intact retina. Screen-printing of carbon ink on 20 µm polyurethane (PU) film was used to realize electrode arrays with electrodes as small as 40 µm in diameter. Passivation was achieved with a holey membrane, realized using laser drilling in a thin (50 µm) PU film. Plasma polymerized EDOT was used to coat the electrode array to improve the electrode specific capacitance. Chick retinas, embryonic stage day 13, both ex-planted and intact inside an enucleated eye, were used. Main results. A novel fabrication process based on printed carbon electrodes was developed and yielded high capacitance electrodes on a soft substrate. Ex vivo electrical recording of retina activity with carbon electrodes is demonstrated. With the addition of organic photo-capacitors, simultaneous photo-electrical stimulation and electrical recording was achieved. Finally, electrical activity recordings from an intact chick retina (inside enucleated eyes) were demonstrated. Both photosensitive retinal ganglion cell responses and spontaneous retina waves were recorded and their features analyzed. Significance. Results of this study demonstrated soft electrode arrays with unique properties, suitable for simultaneous recording and photo-electrical stimulation of the retina at high fidelity. This novel electrode technology opens up new frontiers in the study of neural tissue in vivo.

RF Coupling of Interdigitated Electrode Array on Aerogels for in vivo Nerve Guidance Applications

MRS Advances ◽  
2019 ◽  
Vol 4 (21) ◽  
pp. 1237-1244 ◽  
Author(s):  
Jacob Hadley ◽  
Jack Hirschman ◽  
Bashir I. Morshed ◽  
Firouzeh Sabri
Keyword(s):  
Electrical Stimulation ◽  
Nerve Repair ◽  
Electrode Array ◽  
Silica Aerogels ◽  
Interdigitated Electrode ◽  
In Vivo Models ◽  
Regeneration Rate ◽  
Interdigitated Electrode Array

AbstractAerogels are light-weight porous materials that can tolerate the processing steps required for designing and creating an electric circuit such that the aerogel can be utilized as a substrate for device fabrication. Previous studies have shown the biostability and biocompatibility of polyurea crosslinked silica aerogels both in vivo and in vitro and have demonstrated the potential use of aerogels in biomedical applications. In vitro studies have shown that in the presence of an applied electric field neurites regeneration rate was greater on crosslinked silica aerogels than on tissue culture petridish used as a positive control. Currently, epineural suturing and nerve grafting are the gold standards for surgical reconstruction of injured nerves. However, because they rely on passive mechanisms for reapproximating the distal and proximal terminals they often lead to partial or no recovery leaving room for improvement. The present study investigates the feasibility of a wireless aerogel–based electrically-stimulating implant intended for nerve repair applications. Here the authors report on RF coupling between a secondary coil and a primary coil to wirelessly energize an interdigitated electrode array consisting of eleven interlocking fingers, created on a silica aerogel substrate. The coupling strength was tested both in air and in an animal model, as a function of distance and will be reported. This study focuses on in vivo evaluation and feasibility assessment of a novel active 3-D aerogel-based peripheral nerve repair device. The device utilizes induced EMF to establish a current (hence electrical stimulation) in predetermined pathways where nerve stumps will be confined to. Fundamental differences between in vitro and in vivo models necessitate the in vivo approach. The novel inductively-powered electrical stimulation aerogel-based device utilizes previously established 3-D confinement method for immobilization of nerve stumps, taking advantage of the mesoscopic surface roughness, unique to aerogels. The technique is tested on a mechanically strong, lightweight, porous, and biostable aerogel. Lithographic techniques, gold (Au) thin film metallization, and Faraday induction is used for circuit design, development, and activation.

scholarly journals Highly Flexible Silicone Coated Neural Array for Intracochlear Electrical Stimulation

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
P. Bhatti ◽  
J. Van Beek-King ◽  
A. Sharpe ◽  
J. Crawford ◽  
S. Tridandapani ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Round Window ◽  
Electrode Array ◽  
Auditory Brainstem ◽  
Brainstem Response ◽  
Current Threshold ◽  
Window Approach ◽  
Film Polymer ◽  
Adhesive Coating

We present an effective method for tailoring the flexibility of a commercial thin-film polymer electrode array for intracochlear electrical stimulation. Using a pneumatically driven dispensing system, an average232±64 μm (mean ± SD) thickness layer of silicone adhesive coating was applied to stiffen the underside of polyimide multisite arrays. Additional silicone was applied to the tip to protect neural tissue during insertion and along the array to improve surgical handling. Each array supported 20 platinum sites (180 μm dia., 250 μm pitch), spanning nearly 28 mm in length and 400 μm in width. We report an average intracochlear stimulating current threshold of170±93 μA to evoke an auditory brainstem response in 7 acutely deafened felines. A total of 10 arrays were each inserted through a round window approach into the cochlea’s basal turn of eight felines with one delamination occurring upon insertion (preliminary results of thein vivodata presented at the 48th Annual Meeting American Neurotology Society, Orlando, FL, April 2013, and reported in Van Beek-King 2014). Using microcomputed tomography imaging (50 μm resolution), distances ranging from 100 to 565 μm from the cochlea’s central modiolus were measured. Our method combines the utility of readily available commercial devices with a straightforward postprocessing step on the order of 24 hours.

Sign in / Sign up

Export Citation Format

Share Document