Unformatted text preview: BME 552 Homework Set 1 Assigned Feb 2, 2009 Due Feb 9, 2009 1. Voltage response for current and voltage pulse. Plot the voltage response for a current pulse 1 ms, 100 uA. Assume Rp=1 MOhm. For now, okay to use monophasic pulse, positive current. a. Electrode radii of 50, 250, 500 microns b. Tissue resistivity of 50, 150, 300 Ohm‐cm (nine total plots for (a +b) combinations) c. It was shown in class how pseudo capacity effectively increases the Pt capacitance by 10X, show this effect. (pick 2 cases above to plot) d. Now use a voltage pulse of 3 V for 1 ms. Plot the current through the tissue versus time, repeating a,b,c variations. (11 total plots) e. Comment on i. Voltage response to this current pulse applied to the smallest electrode diameter ii. Current produced by constant voltage stimuli iii. Under which conditions above is a 1V water window limit maintained? 2. Read the Rose 1988 paper on iridium oxide (not platinum) to answer this question. Using the CV (from the paper) below, explain why an anodic bias allows the most charge injection. In terms of power usage, why is a bias inefficient? ...
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- Spring '09
- voltage response, 300 Ohm, 500 microns, voltage pulse. Plot