A team of chemical engineers [Proc. Natl. Acad. Sci. USA, 94, 8984 (1997)] has shown that oxidized polypyrrole supports the growth of structural support cells needed for nerve regeneration in rats. In particular, the team showed that rat nerve cells responded to electrical stimulus from the polymer by producing extensions called neurites that are twice as long as neurites produced in the absence of the stimulus.
(a) Calculate the current generated in a 10-mm-long, 10.0 × 10-6-m-diameter polypyrrole filament that is subjected to a electric field gradient of 12 V. Assume that the conductivity of oxidized polypyrrole is 1.5 x 107 Ω-1m-1. (b) One drawback for this application is that polypyrrole is very fragile and not biodegradable. Suggest a method for evaluating the long-term biocompatibility of polypyrrole fibers in vivo.