Retinal implants

Photodiode arrays have been used as retinal implants [684]. These arrays of p-i-n diodes are fabricated on a thin titanium layer bonded to a glass plate. The total thickness of this flexible structure is 1.5 yum. The microphotodiode array (MPDA) is used to replace photoreceptors (rods and cones) that have become defective due to disease. 

A.P. Chu, K. Morris, R.J. Greenberg, and D.M. Zhou, Stimulus induced pH changes in retinal implants, in Proceedings of 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, pp. 4160-4163. San Francisco (2004). 

D. Zhou and R. Greenberg, Microsensors and microbiosensors for retinal implants. Frontiers in Biosci. 

Bethke W. Present and future retinal implants. Rev Ophthalmol 2006 13(8) 39. 

Recording and relaying. Chief," Finnuala said with a hint of triumph. Her eyes with their retinal implants were unblinking as they tracked him. "And I don t need to tell you this is a public building. Knowing what happens here is a public right under the fourth coronation proclamation."... 

Retinal Implant Microelectrode array for retinal activation fabricated on flexible substrate for adherence to retinal curvature Schematic implanted eye (left), photomicrograph of 1 of 10 bipolar gold electrode pairs with 25 mm inner electrode (right)... 

E. Zrenner, Will retinal implants restore vision . Science, 295, 1022-1025 (2002). 

Release rates are typically well below toxic levels, and higher concentrations of the drug are therefore achieved without systemic side effects. For chronic ocular diseases like cytomegalovirus (CMV) retinitis, implants are effective drug delivery systems. 

Tunc, M., Cheng, X., Ratner, B. D., Meng, E., Huma5om, M. (2007). Reversible thermosen-sitive glue for retinal implants. Retina, 27, 938-942. 

In Situ Characterization of Stimulating Microelectrode Arrays Study of an Idealized Structure Based on Argus II Retinal implants... 

Zrenner E (2002) Will retinal implants restore vision Science 295(5557) 1022—1025 Maynard EM (2001) Visual prostheses. Annu Rev Biomed Eng 3 145-168 Greenberg RJ (2000) Visual prostheses A Review. Neuromodulation 3(3) 161-165 Weiland JD, Humayun MS (2008) Visual prosthesis. Proc IEEE 96 1076-1084 Margaht E, Maia M, Weiland JD et al (2002) Retinal prosthesis for the blind. Surv Ophthalmol 47 335-356... 

Guenther E, Troger B, Schlosshauer B et el (1999) Long-term survival of retinal cell cultures on retinal implant materials. Vision Res 39 3988-3994... 

Since the proposed receiver uses power carrier as data clock, higher the data rate is, higher is the power carrier frequency. In this design, 2-MHz power carrier is chosen to produce 2-Mbps data rate, which the retinal implants with 1000 electrodes require [118]. By the band-pass sampling theory, the sampling rate can be 8, 16, 24 MHz, and so on. Since the sampling rate is proportional to the number of switched-capacitor units, which occupies significant chip area, the minimum... 

An implantable medical device (IMD) operates inside the body to monitor certain physiological parameters. Based on the power requirements of the device, IMDs are divided into two categories (i) active (the devices that need power) and (ii) passive (those that do not require power). Examples of passive IMDs are artificial joints and vascular grafts, whereas active IMDs may include cardiac defibrillators, cardiac pacemakers, neurostimulators, drug pumps, cochlear implants, and retinal implants. The need to broaden the assortment of effectively active IMDs is constantly increasing. 

---