This paper describes a Deep Brain Stimulation device, portable, for chronic experiments on rodents in the context of Parkinson's disease. Our goal is to equip the animal with a device that mimics the human therapeutic conditions. It implies to respect a set of properties such as bilateral current-mode and charge-balanced stimulation, as well as programmability, low power consumption and re-usability to finally reach a suitable weight for long-term experiments. After the analysis of the solutions found in the literature, the full design of the device is explained. First, the stimulation front-end circuit driven by a processor unit, then the choice of supply sources which is a critical point for the weight and life-time of our system. Our low cost system has been realized using commercial discrete components and the overall power consumption was minimized. We achieved 6 days of maximal current stimulation with the chosen battery for a weight of 13.8 g . Finally, the device was carried out in vivo on rats during a 3 weeks experiment as the used implantation technique allows battery changing. This experiment also permits to emphasize the mechanical aspects including the packaging and electrodes holding.

Functional Electrical Stimulation can be used to restore motor functions loss consecutive to spinal cord injury, such as respiratory deficiency due to paralysis of ventilatory muscles. This paper presents a fully configurable IC-centered stimulator designed to investigate muscle stimulation paradigms. It provides 8 current stimulation channels with high-voltage compliance and real-time operation capabilities, to enable a wide range of FES applications. The stimulator can be used in a standalone mode, or within a closed-loop setup. Primary in vivo results show successful drive of respiratory muscles stimulation using a computer-based dedicated controller.

Es wird ein geschichtlicher Überblick über das Zunderungsverhalten von Hartstoffen gegeben. Insbesondere wird das Oxydationsverhalten warm‐ und zunderfester Legierungen auf Titancarbidbasis besprochen. Hartlegierungen aus Titancarbid mit Nickel–Chrom und Kobalt–Chrom‐Legierungen als Bindemetall zeigen eine hervorragende Zunderfestigkeit. Es wird versucht, die physikalisch‐chemischen Vorgänge bei der Zunderung von Metallen auch auf die Zunderung von Carbiden und Carbidlegierungen zu übertragen. Die handelsüblichen Hartmetalle für Zerspanungszwecke auf Wolframcarbidbasis oder Wolframcarbid‐Titancarbid‐Basis zeigen bei Temperaturen unter 1000° linearen Zunderungsmechanismus. Legierungen auf der Basis Titancarbid oder Titanmetall zeigen parabolischen Zunderungsmechanismus. Bei höheren Temperaturen kann sich durch Bildung festhaftender Deckschichten infolge Auftretens flüssiger Phasen in der Deckschicht eine vorübergehende Besserung des Zunderverhaltens einstellen. Es tritt eine Überdeckung des linearen Mechanismus durch den parabolischen ein. Auf Grund von Bildmaterial wird ein Schemabild für die Zunderung nach dem linearen und parabolischen Zunderungsgesetz gebracht.

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Electrical stimulators are widely used in neuro-prostheses. Many different implementations exist. However, no quantitative ranking criterion is available to allow meaningful comparison of the various stimulation circuits and systems to aid the designer. This paper presents a novel Figure of Merit (FOM) dedicated to stimulation circuits and systems. The proposed optimization performance metric takes into account tissue safety conditions and energy efficiency which can be evaluated by measurement. The FOM is used to rank several stimulator circuits and systems.

Bioimpedance spectroscopy is a promising tool for non-invasive monitoring of tissue structure and fluids. With the objective of using it to assess muscle fatigue in vitro, we have developed a measurement bench allowing the monitoring of myoblasts cultures by bioimpedance measurements. This work presents the setup and its characterization, combining modeling and measurements. This setup relies on a microelectrodes array and a commercial impedance analyzer. Its characterization with Phosphate Buffered Saline is coherent with our simulation. The impedance increases at low frequencies after several cell cultures, due to a degradation of the microelectrode interface. Nevertheless, the measurement bench allows us to detect the presence of myoblasts covering the electrodes in a frequency range from 10 kHz to 100 kHz. The measurement bench is therefore suitable to explore the relative impedance variation as a signature of muscle fatigue.

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