We have compared the properties and resistance to DA fouling of a carbon nanotube fiber (CNTF) microelectrode to a traditional carbon fiber (CF) microelectrode. These two materials show comparable electrochemical activities for outer-sphere and inner-sphere redox reactions. Although the CNTF might have a higher intrinsic RC constant, thus limiting its high-frequency behavior, the CNTF show a significantly higher durability than the CF in terms of electrode stability. During constant oxidation of 100 μM DA, the signal measured by the CNTF microelectrode shows a 2-hour window over which no decrease in current is observed. Under the same conditions, the current obtained at the CF microelectrode decreases by almost 50 %. A model of the fouling process, assuming the formation of growing patches of insulator on the surface, has been compared to the data. This model is found to be in good agreement with our results, and indicates a growth rate of the patches in the 0.1 - 2 nm s−1 range.

Classic rotating engines are powerful and broadly used but are of complex design and difficult to miniaturize. It has long remained challenging to make large-stroke, high-speed, high-energy microengines that are simple and robust. We show that torsionally stiffened shape memory nanocomposite fibers can be transformed upon insertion of twist to store and provide fast and high-energy rotations. The twisted shape memory nanocomposite fibers combine high torque with large angles of rotation, delivering a gravimetric work capacity that is 60 times higher than that of natural skeletal muscles. The temperature that triggers fiber rotation can be tuned. This temperature memory effect provides an additional advantage over conventional engines by allowing for the tunability of the operation temperature and a stepwise release of stored energy.