Subject: [Homestead] Throw away the batteries, pour a few drops of ethanol in a tfuel-cell-on-a chip
Date: Sun, 02 Jan 2005 12:38:09 -0500
Alcohol fuel cell goes micro
* December 29, 2004/January 5, 2005*
**
There's a lot of energy in ethanol, which is non-toxic and can be made
cheaply from corn.
Researchers from Saint Louis University, who earlier this year developed
a fuel cell using enzymes to generate electricity from ethanol, have
built a microchip-based version of the device.
The trick to constructing the biofuel cell was creating a sheltered
environment for the enzymes, which are fairly sensitive. The researchers
coated the carbon anode, or positive electrode, of the fuel cell with
polymethylene green, an electocatalyst, then added a nafion membrane
containing the immobilized enzyme alcohol dehydrogenase.
The biofuel cell showed an electrical potential of 0.34 volts and
current density of 53 microamps per square centimeter, according to the
researchers. Multiple cells can be stacked, and the device can be
integrated into a computer chip.
The microchip biofuel cell could eventually be used in place of
rechargeable batteries. Instead of recharging by plugging into a wall
outlet like batteries, the biofuel would be recharged by adding a few
milliliters, or thousandths of a liter, of alcohol. The micro fuel cell
could also be used to power sensors and labs-on-a-chip.
The researchers' prototype consists of a 200-micron-wide,
three-centimeter-long channel in a plastic chip. The bottom of the
channel is lined with the carbon anode, which is covered by the electric
catalyst and membrane. The researchers tested the fuel cell by measuring
the electricity generated as one microliter, or millionths of a liter,
per minute of ethanol flowed through the channel. A drop of water
contains about 50 microliters.
The biofuel cell's enzyme catalysts are renewable. Most fuel cells
catalyze reactions with metals, which are relatively expensive and not
renewable.
The work is scheduled to appear in an upcoming issue of /Lab-on-a-Chip/.
-TECHNOLOGY RESEARCH NEWS
[Homestead] Throw away the batteries, pour a few drops of ethanol in a tfuel-cell-on-a chip,
tvoivozhd, 01/02/2005