Electrochemical reactions from conducting polymers sense available electrochemical energy: sweep rate influence.

Resumen

One of the aims of the modern Science is the design and construction of motors sensing by themselves working conditions. If haptic muscles, nerves and brain originate proprioception, sensing-motors will support development of artificial proprioceptive systems. For that the electrochemical reactions of conducting polymers provide dual sensing-actuating properties and devices. Here a platinum electrode coated with a film of polypyrrole/dodecyl benzene sulfonate was subjected to potential sweeps at several scan rates to check if the reacting material senses those different electrochemical conditions. Both, the consumed electrical energy and the hysteresis corresponding to the parallel charge/potential loop show a relation with the scan rate consisting of the addition of two exponential functions (sensing equations). But while the energy decreases with the scan rate the hysteresis increases with it. The existence of two exponentials indicates two processes: reaction-driven conformational movements of the polymer chains, dominating the kinetics in low scan rates; and diffusion process, leading for the higher ones. There are then two different sensing ranges, one similar to biochemical conformational and allosteric sensors and another one similar to current amperometric electrochemical sensors.