Artificial Retina Using Thin Film Transistor Technology
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Artificial retinas have been desired to recover the sight sense for sight handicapped people. Recently, artificial retinas using external cameras, stimulus electrodes, and three dimensional large scale integrations (LSIs) have been actively developed for patients suffering from retinitis pigmentosa and age related muscular degeneration. So in this seminar, we will discuss about the possibilities of artificial retina using thin film transistors (TFTs), which can be fabricated on transparent and flexible substrates. Electronic photo devices and circuits are integrated on the artificial retina, which is implanted on the inside surface of the living retina at the back part of the human eyeballs. In addition wireless power supply is used to drive the object. This helps to eliminate the connection wires and to realize complete artificial internal organs to improve the quality of life.
Artificial retinas have been ardently desired to recover the sight sense for sight handicapped people. Here electronic photo devices and circuits substitute for deteriorated photoreceptor cells. These devices are implanted inside the eyes. The implanting is classified mainly into two types epiretinal implant and subretinal implant about which we will be discussing in the later chapters.
In this Seminar we will be discussing about the Artificial Retina made using Thin-Film Transistors, which can be fabricated on transparent and flexible substrates. Electronic photo devices and circuits are integrated on the artificial retina, which is implanted on the inside surface of the living retina at the back part of the human eyeballs. Since the irradiated light comes from one side of the artificial retina and the stimulus signal goes out of the other side, the transparent substrate is preferable. Moreover, since the human eyeballs are curved, the exible substrate is also preferable.
It is possible to make spherical shape by designing a petal-like pattern. As a result, the artificial retina using TFTs are suitable for the epiretinal implant on the curved human eyeballs. The artificial retina using TFTs is fabricated using annealing. Earlier wired power supply were used to drive the artificial retina using TFTs to ensure reliable operations However, the wired power supply harms quality of life of the sight-handicapped people because of bothersome connection wires between the artificial retina and external equipments. Therefore, wireless power supply is requisite to eliminate the connection wires and to realize complete artificial internal organs to improve the quality of life.
Blindness is one of the most devastating consequences of disease. We develop electronic artificial retina for restoration of sight to patients suffering from degenerative retinal diseases such as Retinitis Pigmentosa and Age-Related Muscular Degeneration. In these conditions the photoreceptor cells slowly degenerate, leading to blindness. However, many of the inner retinal neurons that transmit signals from the photoreceptors to the brain are preserved to a large extent for a prolonged period of time. Foerster was the first to discover that electrical stimulation of the occipital cortex could be used to create visual percepts, phosphenes. Implantable microelectronic retinal prostheses represent a promising means of restoring sight to the blind. The conventional model of such devices includes an externally worn digital camera which samples the wearers visual environment. This stream of visual information is then processed before being conveyed via wireless to an implanted neuro stimulator connected to an array of electrodes placed within or adjacent to the retina. Electrical stimuli are thereby delivered to the surviving neurons of the retina to effect the perception of phosphenes.