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G. Swider, L. Theogarajan, V, W. Drohan, S.K. Kelly, B. Yomtov, J.L. Wyatt, J.F. Rizzo; Testing and Qualification of the Boston Retinal Implant Chip . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3187.
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© ARVO (1962-2015); The Authors (2016-present)
Our prototype retinal implant for animal studies has at its core a communications and stimulation chip of 25,000 transistors (Wyatt et al, ARVO paper #1146, 2005). That chip was tested and qualified upon return from fabrication. We measured the functional performance resulting from process parameters versus the designed specifications.
The chips were tested by sending commands at various input data rates and RF carrier frequencies. We measured a range of charge levels per electrode and for multiple electrodes. Bias values of the chip were also tested for variability of performance. Two versions on the chip were produced. One was a 40–pin version for use in an implant. The other was a 52–pin version with additional I/O ports that allowed testing of individual functional blocks within the chip.
Input data rates were varied from 16.667 kHz–1.429MHz. At a nominal data frequency of 100 kHz, charge pulses were successfully delivered to 15 electrode models. Pulses were incremented in steps of 30µA and ranged from zero to 930µA. The power consumption of the chip ranged from 1.2mW at a 25 kHz data rate to 3.24mW at a data rate of 714 kHz. The results above represent bench testing conditions.
Our custom designed stimulator chip tests successfully and will be used for pre–clinical tests of our prosthetic system.
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