Electrokinetic Generation Efficiency With Finite External Loads

Electrokinetic (EK) pumping efficiency has recently been a hot topic due largely to its applications in microfluidics for liquid transport. As the Onsager reciprocity relation suggests that the exact opposite of EK pumping is EK generation, experimental study on the efficiency of the latter is seldom reported. This paper examines electrokinetic generation efficiency in the presence of finite external loads through the use of different ceramic filters. The electrical output power was measured experimentally as a function of different external loadings. When the experiments were performed continuously on subsequent days, the EK generation efficiency for all the tested filters can be made to increase and approach a maximum limit. The experimental data also indicated that, when pore size of the filter decreases, the curve for potential versus current becomes more non-linear and the maximum efficiency does not occur when the current is half the zero-potential current.