ITALIAN ENGINEERS are to begin tests on the world's smallest fuel cell, which has been produced on a silicon wafer using methods similar to microchip manufacture. Fuel cells promise higher energy output than a battery and higher efficiency than a petrol or diesel combustion engine. The auto-motive industry has spent years developing a fuel cell engine for a family saloon, but with little success.

Now semiconductor firm STMicroelectronics hopes that the technology can be successfully transferred for use in laptops, mobile phones and other portable equipment.

Lead researcher Dr Corrado Spinella, who is also departmental director at Sicily's lstituto per la Microelettronica e Microsistemi, said the microfuel cell, which is small enough to fit on to a microchip, is a miniature proton-exchange membrane cell.

The tests are aimed at optimising the cell's membrane and evaluate the performance of the hydrogen electrode. This will involve pushing gaseous hydrogen through the cell's micro channels, which are etched into the surface of the silicon. The team will use a chemical solution to monitor proton flow in the cell, by measuring changes in the solution's pH value.Spinella said the tests will allow researchers to define the maximum current density and voltage, or power that the tiny fuel cell can generate.

The research team produced the cell using an electrochemical micro-machining technique to etch its structure on to the silicon wafer. Silicon is usually etched with UV light in the microchip industry.

However, Spinella's research partners at STMicroelectronics developed the 'epitaxy' process to create the 'tunnels' necessary for the proton exchange. Epitaxy involves 'growing' a single defect-free layer of silicon over the etched trench to form a tunnel or tube.

As well as the fuel cell on a chip the technology could also he used for 'micro fluidic' applications. The cell's 'buried' trenches can act as tiny channels to direct organic material for analysis, which could include DNA.

Spinella has received funding of €100,000 (£70,000) from the Italian government, and hopes that the first prototypes integrating both micro fuel cells and conventional electronic circuits can be produced within the next two to three years.

However, more funds will be needed to take the technology to market. 'We expect further funding from the Italian research ministry in the order of €1m (£700,000) over the next two years', he said.