Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 3

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

The Effect of Return Electrode Position on Induced Electric Fields for Electrical Stimulation of Retinal Ganglion Cells

100%
Celik M.
|
EN
Age-related macular degeneration and retinitis pigmentosa are the most countered eye diseases that damage photoreceptors and cause to lose the visual sense. To regain the visual sense, studies are focused on the electrical stimulation of nerve cells remain intact. The electrical stimulation is carried out with the electrode arrays that include a certain number of stimulation electrodes and a common return electrode. In this study, the retinal stimulation is modelled using a computational model to investigate stimulation performance depending on the return electrode position and its geometrical properties. Stimulation induced electric field, current density and temperature over the retinal tissue are examined. It is seen that closer placement of return electrode and stimulation electrodes causes high electric field intensity and current density between electrodes, which is quite risky for long term chronic implementation by the reason of the increase in the temperature beyond the safe limits. It is concluded that there is an indispensability for the distances, three to five times of the electrode diameter, between electrodes to avoid electrode corrosion and tissue damage.
2
Content available remote

An Efficient Inductive Coil Link Design for Wireless Power Transfer to Visual Prostheses

63%
Celik M., Aydin E.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 3
535-537
EN
Powering therapeutic devices plays a crucial role in the design phase of implantable electronic units. Batteries could not provide sufficient charge storage, used for the lifetime of the device, considering the space available for them. As sophisticated surgical procedures are required with the possible trauma to the patient such as material discrepancy and tissue damage, replacement is quite risky and not an option. Thus, therapeutic devices, especially visual prostheses, receive power wirelessly through inductive coil links which are connected to a battery outside the body. An inductive link is based on the main principle that there are two components such as primary and secondary units. Although primary unit includes the battery outside the body, power transmitter, and control unit, secondary unit under the skin contains amplifier, rectifier regulators, and power control unit. In this study, an inductive coil link is modelled to evaluate fundamental design specifications for visual prostheses. Inductive coil link parameters are quantitatively investigated so that maximum power transfer efficiency and miniaturization, which are critically important for electronics placed in intraocular region, are provided. Considering 20 mm distance, it is concluded that the separation and the size of the coil pair, loop diameter, frequency have a major role to determine the system performance.
3
Content available remote

Modelling of Stimulation Environment Using Monophasic Rectangle Pulse for Various Stimulation Parameters

63%
Celik M., Karagoz I.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2B
B-297-B-299
EN
Recently, both the progress in some technological fields and multidisciplinary studies conducted with collaboration from different branches of science have impressive effect on clinically tested systems. Studies on development of visual prosthesis, which is based on passing damaged parts of the visual pathway and electrically stimulating nerve cells remaining intact, date back to elicit visual sense in blind patients. Investigation of some research topics, in silico, which should be taken into consideration in the design phase before expensive animal experiments provides great advantages in terms of both financial and time issues. In this study, factors such as heat, electric field distribution for current thresholds, current density which should be discussed in the design phase are simulated using monophasic rectangle pulses depending on various stimulation parameters with developed computational retina model. Change of heat, electric field, current density in points selected from center and periphery of retina tissue are investigated for various stimulation parameters. As a result, it is concluded that distribution of heat and electric field intensity over the periphery retina are much less than center region. Moreover, when larger pulse width is used, change of heat and electric field intensity seems much more in regions from center retina near stimulation electrode. Current density is higher in the sharp ends of the electrode than flat regions. Besides, when the size of stimulation electrode increases, electric field distribution becomes more uniform.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.