A micro-fluidic galvanic cell as an on-chip power source

We present a micro-fluidics actuated galvanic cell for on demand power generation. The galvanic cell is an aluminum anode/alkaline electrolyte/air cathode cell. The concept is based upon an actuation mechanism that pushes an electrolyte into a micro-channel containing electrodes. When the electrolyte reaches the electrodes of a galvanic cell, it produces energy through an electrochemical reaction. The proof of concept is presented herein by fabricating and characterizing a single cell using micro-fabrication techniques. The actuation mechanism is based on the thermal expansion of a working fluid. A brief discussion on the optimization of this actuation is also presented. The open voltage of this micro-cell was experimentally measured to be around 1.9 V. The Al/air galvanic cell chemistry has been compared with commercial Zn/air battery and has been found to perform better. The present micro-cell design (with an area of 0.75 cm(2)), is capable of providing an energy of 5 J after 6.0 min when subjected to a load of 20 Omega. The actuation mechanism takes less than a minute and consumes about 3.5 J. (C) 2003 Elsevier B.V. All rights reserved.