Abstract
Purpose: :
The prototype Boston Retinal Implant receives data input via a wireless RF link. To arrive at an optimum design, a means for varying the input parameters (i.e. electrode current, pulse widths, charge balance, bias settings, carrier/ data frequency, repetition rate, waveform filter settings) must be available.
Methods: :
To permit control over input parameters, we built a software program written entirely in Labview that runs on a standard PC and designed a flexible, powerful and user–friendly graphical user interface (GUI). The software supplies a suitably encoded and modulated RF stream to drive the implant chip. The software runs a PXI computer that includes an Arbitrary Waveform Generator driven by a memory pattern created by the software. The GUI uses a multi–tabbed "index card" presentation that enables the user to access many program settings from one screen using logical function groupings. A recipe save/restore function makes use of common setups easy and error proof. Electrode current settings (0 – 775 microA) are allowed all electrodes but one that can received double this current. Pulse widths (0 – 100 msec) and repetition rates (0.01 to 10000 Hz) are allowed.
Results: :
The software program is completed and performs faithfully and robustly to the above specs, as revealed by monitoring with an oscilloscope. We have begun to use this program to perform in vivo testing of our stimulating system in the laboratory as a prelude to eventual human testing. Two systems have been implemented, to allow users full access to one system while a second is further optimized with added features.
Conclusions: :
Our custom–designed software has provided a flexible and robust means to control our stimulating chip. Our graphical design method provides a rapid, robust, maintainable and user–friendly body of code. A future portable DSP version for patients is under development.
Keywords: retina • electrophysiology: non-clinical • perception