New epiretinal implant with integrated sensor chips for optical capturing shows a good biocompatibility profile in vitro and in vivo.

Background: Retinal degenerative diseases, e.g., retinitis pigmentosa, cause a severe decline of the visual function up to blindness.

Development and in vitro validation of flexible intraretinal probes.

The efforts to improve the treatment efficacy in blind patients with retinal degenerative diseases would greatly benefit from retinal activity feedback, which is lacking in current retinal implants. While the door for a bidirectional communication device that stimulates and records intraretinally has been opened by the recent use of silicon-based penetrating probes, the biological impact induced by the insertion of such rigid devices is still unknown. Here, we developed for the first time, flexible intraretinal probes and validated in vitro the acute biological insertion impact in mouse retinae compared to standard silicon-based probes.

The very large electrode array for retinal stimulation (VLARS)-A concept study.

Objective: The restoration of vision in blind patients suffering from degenerative retinal diseases like retinitis pigmentosa may be obtained by local electrical stimulation with retinal implants. In this study, a very large electrode array for retinal stimulation (VLARS) was introduced and tested regarding its safety in implantation and biocompatibility. Further, the array's stimulation capabilities were tested in an acute setting.

Toward a Bidirectional Communication Between Retinal Cells and a Prosthetic Device - A Proof of Concept.

Significant progress toward the recovery of useful vision in blind patients with severe degenerative retinal diseases caused by photoreceptor death has been achieved with the development of visual prostheses that stimulate the retina electrically. However, currently used prostheses do not provide feedback about the retinal activity before and upon stimulation and do not adjust to changes during the remodeling processes in the retina. Both features are desirable to improve the efficiency of the electrical stimulation (ES) therapy offered by these devices.

[Technological Set-up of Epiretinal Implants].

In blinded patients, visual prostheses can restore visual perception by appropriate electrical stimulation of retinal nerve cells. This article presents the basic technological principles of retinal prostheses, using an epiretinal implantable visual prosthesis as example. An implantable visual prosthesis typically consists of extraocular and intraocular sections.

Properties of Retinal Precursor Cells Grown on Vertically Aligned Multiwalled Carbon Nanotubes Generated for the Modification of Retinal Implant-Embedded Microelectrode Arrays.

Background. To analyze the biocompatibility of vertically aligned multiwalled carbon nanotubes (MWCNT), used as nanomodification to optimize the properties of prostheses-embedded microelectrodes that induce electrical stimulation of surviving retinal cells. Methods.

Development of very large electrode arrays for epiretinal stimulation (VLARS).

Background: Retinal implants have been developed to treat blindness causing retinal degenerations such as Retinitis pigmentosa (RP). The retinal stimulators are covering only a small portion of the retina usually in its center. To restore not only central vision but also a useful visual field retinal stimulators need to cover a larger area of the retina.

Development of a very large array for retinal stimulation.

Retina degeneration is one of the leading causes of blindness nowadays and cannot be cured in most cases. It has been shown that electrical stimulation of retinal ganglion cells can generate visual perceptions and therefore implantable electrode arrays can be possible treatment for these patients. Most implants developed for that purpose use electrode arrays with a size of a few millimeters squared and therefore could restore only a very small field of vision and hardly improve orientation in an unknown environment.

Stacked planar micro coils for single-sided NMR applications.

This paper describes planar micro structured coils fabricated in a novel multilayer assembly for single-sided NMR experiments. By arranging the coil's turns in both lateral and vertical directions, all relevant coil parameters can be tailored to a specific application. To this end, we implemented an optimization algorithm based on simulations applying finite element methods (FEMs), which maximizes the coil's sensitivity and thus signal-to-noise ratio (SNR) while incorporating boundary conditions such as the coil's electrical properties and a localized sensitivity needed for single-sided applications.

Flexible multi-electrode array with integrated bendable CMOS-chip for implantable systems.

Micro-electrodes and micro-electrode arrays (MEAs) for stimulating neurons or recording action potentials are widely used in medical applications or biological research. For medical implants in many applications like brain implants or retinal implants there is a need for flexible MEAs with a large area and a large number of stimulation electrodes. In this work a flexible MEA with an embedded flexible silicon dummy CMOS-chip facing these challenges has been designed, manufactured and characterized.

A novel fully implantable wireless sensor system for monitoring hypertension patients.

This paper presents a novel fully implantable wireless sensor system intended for long-term monitoring of hypertension patients, designed for implantation into the femoral artery with computed tomography angiography. It consists of a pressure sensor and a telemetric unit, which is wirelessly connected to an extracorporeal readout station for energy supply and data recording. The system measures intraarterial pressure at a sampling rate of 30 Hz and an accuracy of ±1.

Implantation and explantation of an active epiretinal visual prosthesis: 2-year follow-up data from the EPIRET3 prospective clinical trial.

Purpose: The EPIRET3 retinal prosthesis was implanted in six volunteers legally blind from retinitis pigmentosa (RP) and removed after 4 weeks. Two years later, these subjects were re-examined to investigate ocular side effects and potential changes to quality of life.

Methods: Vision-related quality of life was recorded using the NEI-VFQ-25 questionnaire.

Bioprocess control in microscale: scalable fermentations in disposable and user-friendly microfluidic systems.

Background: The efficiency of biotechnological production processes depends on selecting the best performing microbial strain and the optimal cultivation conditions. Thus, many experiments have to be conducted, which conflicts with the demand to speed up drug development processes. Consequently, there is a great need for high-throughput devices that allow rapid and reliable bioprocess development.

Microfluidic biolector-microfluidic bioprocess control in microtiter plates.

In industrial-scale biotechnological processes, the active control of the pH-value combined with the controlled feeding of substrate solutions (fed-batch) is the standard strategy to cultivate both prokaryotic and eukaryotic cells. On the contrary, for small-scale cultivations, much simpler batch experiments with no process control are performed. This lack of process control often hinders researchers to scale-up and scale-down fermentation experiments, because the microbial metabolism and thereby the growth and production kinetics drastically changes depending on the cultivation strategy applied.

Implantation and explantation of a wireless epiretinal retina implant device: observations during the EPIRET3 prospective clinical trial.

Purpose: Visual sensations in patients with blindness and retinal degenerations may be restored by electrical stimulation of retinal neurons with implantable microelectrode arrays. A prospective trial was initiated to evaluate the safety and efficacy of a wireless intraocular retinal implant (EPIRET3) in six volunteers with blindness and RP.

Methods: The implant is a remotely controlled, fully intraocular wireless device consisting of a receiver and a stimulator module.

Intraocular epiretinal prosthesis to restore vision in blind humans.

Visual sensations in blind patients suffering from retinal degenerations may be restored by electrical stimulation of retinal neurons using implantable microelectrode arrays. The EPI-RET-3 project was initiated to evaluate a wireless intraocular retinal implant system for human use in terms of safety and efficiency. The implant is a remotely controlled fully intraocular prosthesis consisting of a receiver and a stimulator module.

Micro-bioreactors for fed-batch fermentations with integrated online monitoring and microfluidic devices.

In this study an array of micro-bioreactors based on the format of 48-well microtiter plates (MTP) is presented. The process parameters pH-value and biomass are monitored online by a combination of different sensors, the biolector measurement technology and conductance measurements. A microfluidic device dispenses two fluids individually into each well for controlling the pH-value of fermentations.

An implantable microsystem as a vision prosthesis.

Blindness is often the result of degeneration of the light sensitive rods and cones of the retina in conditions such as retinitis pigmentosa and macula degeneration. An implantable vision prosthesis has been developed that electrically stimulates the retinal ganglion cells in such a way that action potentials in retinal ganglion cells are evoked, causing a visual sensation in the visual cortex. Clinical trials are about to be conducted.

Sputtered iridium oxide for stimulation electrode coatings.

This work deals with the reactive RF-powered sputter deposition of iridium oxide for use as the active stimulation layer in functional medical implants. The oxygen gettered by the growing films is determined by an approach based on generic curves. Films deposited at different stages of oxygen integration show strong differences in electrochemical behaviour, caused by different morphologies.

Iridium sputtered at varying pressures and target-substrate-distances evaluated for use as stimulation electrode material.

Iridium was sputtered as the top layer of stimulation electrodes. The coatings were varied in their morphology by adjusting the total deposition pressure and the working distance (WD) of target and substrate. It is shown that the resulting different kinds of morphologies have a strong influence on stimulation characteristics.

Transponder-based sensor for monitoring electrical properties of biological cell solutions.

An inductive passive remote sensor circuit for monitoring fermentation processes is presented. The sensor circuit consists of an interdigital capacitor and a planar coil structured on a glass laminated FR4-printed circuit board. This circuit resonates at frequencies between 2 and 4 MHz.

[Epiretinal visual prostheses].

Epiretinal implants consist of a camera chip capturing the scene, a visual processor calculating retina-specific pulse sequences, a transponder for data and energy, and the implant itself. The implant consists of a receiver integrated into a posterior chamber lens, a microcable, and the retina stimulator. The stimulator is fixated onto the retinal surface using retinal tacks.

Theoretical calculations and performance results of a PZT thin film actuator.

High piezoelectric coupling coefficients of PZT-based material systems can be employed for actuator functions in micro-electro-mechanical systems (MEMS) offering displacements and forces which outperform standard solutions. This paper presents simulation, fabrication, and development results of a stress-compensated, PZT-coated cantilever concept in which a silicon bulk micromachining process is used in combination with a chemical solution deposition (CSD) technique. Due to an analytical approach and a finite element method (FEM) simulation for a tip displacement of 10 microm, the actuator was designed with a cantilever length of 300 microm to 1000 microm.

Vascular capsule for telemetric monitoring of blood pressure.

Purpose: Development and experimental evaluation of an intravascular monitoring system for telemetric measurement of blood pressure and heart rate.

Materials And Methods: The monitoring system consists of an implantable silicone capsule (diameter 2.3 mm), containing a dedicated microchip with pressure sensors and signal-processing circuits as well as an antenna for wireless data and energy transfer using 6.