Directional growth of polypyrrole and polythiophene wires

This work establishes an innovative electrochemical approach to the template-free growth of conducting polypyrrole and polythiophene wires along predictable interelectrode paths up to 30 um in length. These wires have knobby structures with diameters as small as 98 nm. The conductivity of the polypyrrole wires is 0.5+/=0.3 S cm-1; that of the polythiophene wires is 7.6+/=0.8 S cm-1. Controlling the growth path enables fabrication of electrode-wire-target assemblies where the target is a biological cell in the interelectrode gap. Such assemblies are of potential use in cell stimulation studies.Peer reviewedPhysicsMicrobiology and Molecular Genetic

Investigation of Ig.G adsorption and the effect on electrochemical responses at titanium dioxide electrode

The adsorption of Immunoglobulin G on a titanium dioxide (TiO2) electrode surface was investigated using 125I radiolabeling and electrochemical impedance spectroscopy (EIS). 125I radiolabeling was used to determine the extent of protein adsorption, while EIS was used to ascertain the effect of the adsorbed protein layer on the electrode double layer capacitance and electron transfer between the TiO2 electrode and the electrolyte. The adsorbed amounts of Ig.G agreed well with previous results and showed approximately monolayer coverage. The amount of adsorbed protein increased when a positive potential was applied to the electrode, while the application of a negative potential resulted in a decrease. Exposure to solutions of Ig.G resulted in a decrease of the double layer capacitance (C) and an increase in the charge-transfer resistance (R2) at the electrode solution interface. As more Ig.G adsorbed onto the electrode surface, the extent of C and R2 variation increased. These capacitance and charge-transfer resistance variations were attributed to the formation of a proteinaceous layer on the electrode surface during exposure

Fast carbon nanotube charging and actuation

Millisecond timescale charging and contraction of carbon nanotube artificial muscle is demonstrated. The mechanical power-to-mass ratio is five times higher than in human muscle, and electrical power transfer is ten times greater than observed in supercapacitors. These results show that, despite their electrochemical nature, carbon nanotube electrodes (see figure) can respond surprisingly quickly