Casio Develops an EO Pump Designed for Reformed Methanol Fuel Cell Systems Used in Mobile Devices

Casio Develops an EO Pump Designed for Reformed Methanol Fuel Cell Systems Used in Mobile Devices

Electro Osmotic (EO) pump (from foreground) The Electro Osmotic Pump, Micro Reformation Module ver.33, and Fuel-Cell Stack

TOKYO, November 29, 2006 - Casio Computer Co., Ltd., has developed an electroosmotic (EO) pump optimized for use in Reformed Methanol Fuel Cell (RMFC) systems for mobile devices. The pump is able to dispense precise quantities of methanol while maintaining high pressure in a compact 0.5-cc unit. The pump is made from materials developed by Nano Fusion Technologies, Inc. Casio's successes in the development of RMFC systems for mobile devices include key devices such as a thermally insulated microreactor that extracts hydrogen from methanol, and a fuel cell stack. A working demonstration of the company's System Version 35, incorporating the above-mentioned components, was shown at the Fuel Cell Seminar, a scientific conference on fuel cells held from November 13 to 17, 2006, in Honolulu, Hawaii. Casio aims to start delivering samples of the system for performance evaluation in fiscal 2008. The newly developed EO pump is a fuel-supply micropump that is indispensable for the miniaturization of fuel cells. The pump is made of electroosmotic material, a dielectric substance such as silica, which has electric potential when it comes in contact with a liquid. By applying voltage to the outside of the unit, it causes the liquid inside to move. Despite its compact size, the pump can dispense liquid at high pressure, and since it has no motor, it offers the benefit of noiseless operation and eliminates problems such as pulsation. Casio combined its own proprietary technology with electroosmotic material developed by Nano Fusion (7mm in diameter and 1 mm thick) to develop the optimal liquid fuel pump for RMFC systems for use in mobile devices. Casio has resolved problems inherent in EO pump technology such as the electroosmotic material's susceptibility to damage from impact, or the buildup of vapor bubbles resulting from liquid electrolysis. The result is a high-performance EO pump in a compact unit only 0.5 cc in total volume that can maintain a flow rate of 90µl/minute even at 100 kPa. In the future, Casio will continue its research to further improve the performance of this technology with a view to achieving practical application.

Main Technical Features . The EO pump uses a resin material that facilitates capillary action within the pump to draw in methanol when the fuel cartridge is first attached, helping to prime the pump. . A combination of a hydrophobic membrane and a hydrophilic membrane is used to reduce the buildup of vapor bubbles - a potential byproduct of electrolysis of the water in the methanol-water solution - which would otherwise limit the flow of liquid through the pump. . Casio has used elastic materials to create a shock resistant construction to reduce the risk of damage to the sensitive electroosmotic materials used in the pump.

Operating Principles of the EO Pump When voltage is applied to electrodes made of micro-porous electroosmotic material, the surplus cations in the liquid migrate to the negative pole. The viscosity of the liquid itself causes the liquid to flow in the direction of the cations, creating a pump function.

Specifications of the EO Pump Movement principle Electro-Osmotic flow Total Volume (Unit Size) 0.5cc (11mm x 11mm x 4 mm) Fluid MeOH 60wt% water solution Operating voltage 30V P-Q property (pressure vs. flow rate) 120µl/minute at 0 kPa back pressure 100µl/minute at 40 kPa back pressure 90µl/minute at 100 kPa back pressure Power consumption 100mW

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