Power generation by pressure-driven transport of ions in nanofluidic channels.

We report on the efficiency of electrical power generation in individual rectangular nanochannels by means of streaming currents, the pressure-driven transport of counterions in the electrical double layer. Our experimental study as a function of channel height and salt concentration reveals that the highest efficiency occurs when double layers overlap, which corresponds to nanoscale fluidic channels filled with aqueous solutions of low ionic strength. The highest efficiency of approximately 3% was found for a 75 nm high channel, the smallest channel measured. The data are well described by Poisson-Boltzmann theory with an additional electrical conductance of the Stern layer.