Electrokinetic microchannel battery by means of electrokinetic and microfluidic phenomena

Abstract

Pressure-driven flow in a microchannel induces a streaming current due to the presence of an electrical double layer in the interface between the electrolyte solution and channel wall. As the streaming current is of the order of a nano-amphere and is additive, we propose here a method to develop an electrokinetic battery consisting of an array of microchannels that converts the hydrostatic pressure of a liquid into electrical work. We have given oscillating analytical solutions by means of an electrical circuit analysis to model the multi-microchannel battery. Using superposition of the appropriate Fourier series, the derived analytical solutions are useful to predict the current when there is more general time-dependent flow through a microchannel array. To illustrate the idea, we have studied steady-state pressure-driven flow in micropore porous glass filter and compared the results with those predicted from our model. From a 30 cm hydrostatic pressure drop, an external current of 1–2 µA was obtained by means of water passing through the micropore porous glass filter. A larger current can be obtained by simply using a solution with higher salt concentration. This results in a new and potentially useful method of energy conversion by means of an array of microchannels.

Electrokinetic Power Generation from Liquid Water Microjets

“…1 A number of studies have focused on producing electrokinetic currents by forcing water through porous materials. [2][3][4] Others have concentrated on the electrical properties of single well-defined channels. [5][6][7][8][9][10] Similarly, in a recent paper, we demonstrated intrinsic electrokinetic molecular hydrogen production by flowing pure water through metal microchannels.…”

Electrokinetic Hydrogen Generation from Liquid Water Microjets

“…5,7 By mid-century, streaming currents were identified as the cause of otherwise mysterious petroleum industry explosions. 5,8 More recently, Kwok and others have used streaming currents to generate electrical power, [9][10][11] with Kwok describing the design of an "electrokinetic microchannel battery." In the present study, streaming currents are used to convert hydrostatic pressure directly into both electrical energy as well as stored chemical energy in the form of molecular hydrogen.…”

Electrical power generation by mechanically modulating electrical double layers

“…Numerous studies of the EDL have explained many electrokinetic phenomena 9,10 , such as, electro-osmosis, electrophoresis and streaming current. There is one prior approach, which uses a streaming current, to generate electrical energy in micro-fluidic channels 11,12 . A drawback of this technique is that a continuous pressure gradient must be maintained across the channel in order to generate an electrical current.…”