A Treatise on Electrode Carrier Dislocation in Visual Prosthetic Devices.

Visual implants electrically activate adjacent neurons to induce artificial perception for visual impairment patients to restore some sight. Proximity of electrode carrier to the ganglion cell has attracted careful consideration due to its implications on secure electrochemical and single-localized stimulation. In this study, we postulate a novel strategy to treat the proximity of electrode-cell. A simulation framework includes the carrier dislocation using the geometric parameters of Argus II® epiretinal electrode carrier design. Lastly, we present results on the offset angle of displacement.Clinical Relevance- This postulates a novel strategy to treat the dislocation of electrode carrier confined with a single tack.

Electrical Impedance Spectroscopy for Characterization of Prostate PC-3 and DU 145 Cancer Cells.

The impedance profile of the human PC-3 and DU 145 prostate cancer cells were recorded and compared using Electrical Impedance Spectroscopy. Cells were measured in a special chamber using a four terminal setup to avoid parasitic effects of electrode polarization in low frequencies. Our results show that the two cancer cell lines are readily distinguishable by their impedance spectrum. As PC-3 cells have been shown to be spontaneously metastatic in previous xenograft experiments while DU 145 cells were non-metastatic, Electrical Impedance Spectroscopy has the potential to be developed into a simple diagnostic tool to distinguish metastatic from non-metastatic cells.

Long-term decoding of movement force and direction with a wireless myoelectric implant.

OBJECTIVE: The ease of use and number of degrees of freedom of current myoelectric hand prostheses is limited by the information content and reliability of the surface electromyography (sEMG) signals used to control them. For example, cross-talk limits the capacity to pick up signals from small or deep muscles, such as the forearm muscles for distal arm amputations, or sites of targeted muscle reinnervation (TMR) for proximal amputations. Here we test if signals recorded from the fully implanted, induction-powered wireless Myoplant system allow long-term decoding of continuous as well as discrete movement parameters with better reliability than equivalent sEMG recordings. The Myoplant system uses a centralized implant to transmit broadband EMG activity from four distributed bipolar epimysial electrodes. APPROACH: Two Rhesus macaques received implants in their backs, while electrodes were placed in their upper arm. One of the monkeys was trained to do a cursor task via a haptic robot, allowing us to control the forces exerted by the animal during arm movements. The second animal was trained to perform a center-out reaching task on a touchscreen. We compared the implanted system with concurrent sEMG recordings by evaluating our ability to decode time-varying force in one animal and discrete reach directions in the other from multiple features extracted from the raw EMG signals. MAIN RESULTS: In both cases, data from the implant allowed a decoder trained with data from a single day to maintain an accurate decoding performance during the following months, which was not the case for concurrent surface EMG recordings conducted simultaneously over the same muscles. SIGNIFICANCE: These results show that a fully implantable, centralized wireless EMG system is particularly suited for long-term stable decoding of dynamic movements in demanding applications such as advanced forelimb prosthetics in a wide range of configurations (distal amputations, TMR).

Synthesis of an organic conductive porous material using starch aerogels as template for chronic invasive electrodes.

We report the development of an organic conducting mesoporous material, as coat for invasive electrodes, by a novel methodology based on the use of starch aerogel as template. The poly(3,4-ethylenedioxythiophene) (PEDOT) aerogel was synthesized by polymerization of 3,4-ethylenedioxythiophene within a saturated starch aerogel with iron (III) p-toluenesulfonate (oxidizing agent) and subsequent removal of the polysaccharide template, followed by supercritical CO2 drying. The chemical structure and oxidation state of the resulting material were studied by Raman spectroscopy. The morphology and surface properties of the obtained nanoporous material were investigated by scanning electron microscopy (SEM), micro computed tomography (µCT) and nitrogen adsorption-desorption techniques. The composition and thermal behaviour were evaluated by energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) respectively. A preliminary biocompatibility test verified the non-cytotoxic effects of the PEDOT aerogel. The large surface area and wide pore size distribution of the PEDOT conductive aerogel, along with its electrical properties, enable it to be used as extracellular matrix scaffold for biomedical applications.