Method and Apparatus to Provide Safety Checks for Neural Stimulation
In electrically stimulating neural tissue it is important to prevent over stimulation and unbalanced stimulation, which would cause damage to the neural tissue, the electrode, or both. It is critical that neural tissue is not subjected to any direct current or alternating current above a safe threshold. Further, it is important to identify defective electrodes, as continued use may result in neural damage and further electrode damage. The present invention presents system and stimulator control mechanisms to prevent damage to neural tissue.
1 . A method of stimulating neural tissue comprising:
providing a neural stimulator including a plurality of electrodes suitable to stimulate neural tissue;
receiving external input for neural stimulation;
determining a desired cathodic pulse amplitude based on the external input;
calculating an anodic pulse width at a predetermined amplitude to balance the cathodic pulse; and
stimulating neural tissue according to the cathodic and anodic pulses.
3 . The method according to claim 1 , further comprising shorting the electrodes to ground after the anodic pulse.
4 . The method according to claim 1 , further comprising appending a pulse to compensate for imbalance.
5 . The method according to claim 1 , wherein the input is video input from a video processor.
6 . The method according to claim 5 , wherein the step of stimulating neural tissue is stimulating visual neurons to form artificial vision.
7 . The method according to claim 1 , wherein the step of stimulating neural tissue according to external input includes receiving input from multiple sources.
8 . The method according to claim 1 , further comprising:
determining a safe stimulation level for all electrodes;
calculating a sum of stimulation on the plurality of electrodes based on the external input; and
reducing the stimulation on each electrode by the amount necessary, not to exceed the safe level for the plurality of electrodes.
9 . The method according to claim 8 , where the step of reducing comprises reducing the stimulation on each electrode in equal proportion.
10 . The method according to claim 8 , wherein the step of receiving input for neural stimulation comprises receiving input from multiple sources and the step of calculating a sum of stimulation includes a sum from all sources.
11 . The method according to claim 8 , wherein the step of stimulating neural tissue is stimulating visual neurons to form artificial vision.