Beta-voltaic batteries being developed for US Army

Washington : The US military's research branch -- the Defense Advanced Projects Research Agency (DARPA) -- which is based in Virginia, is reportedly funding a project to develop beta-voltaic batteries, or cells that generate current from radioactive materials that emit electrons (so-called beta emitters).

Beta-voltaic cells are essentially semi-conducting diodes. In such cells, an electron from a radioactive source does the job.

DARPA has funded a team at Cornell University in, New York, US, to come up with a way of increasing the surface area of betavoltaic cells. The Cornell team reckons the latest techniques for carving silicon makes it possible to create 3D diode junctions, resembling pillars, on top of a silicon carbide substrate.

The design consists of a silicon carbide substrate with several diode junction columns, like a miniature version of the Parthenon. The spaces in between are then filled with a radioactive beta emitter such as tritiated water (in which hydrogen is replaced by its radioactive isotope tritium), and the device is sealed.

The team speculates that such batteries would generate enough power to run something like a pacemaker for 20 years. This type of battery should be safe since beta particles are relatively low energy and can be easily shielded.

Meanwhile, the Office of Naval Research is looking for better ways of tracking eyes in the hope of developing military applications, such as tracking a fighter pilot's gaze.

So it has a funded James DiCarlo, a neuroscientist at the Massachusetts Institute of Technology in Cambridge, US, to develop a magnetic contact lens.

In this instance, a soldier would wear the lenses and a magnetic sensor attached to the side of his or her head. This sensor would have the potential to pick up any changes in the local magnetic field and works out how the wearer's eyes are moving.

The system should work regardless of head orientation and movement, lighting condition,s or "face furniture" such as goggles or glasses. The team says the magnetic lenses could also let disabled people control equipment such as wheelchairs.

The information displayed by a hologram depends on the angle at which you view it. This allows them to produce 3D images, but it also allows them to store a high density of other types of data.

Now, Microsoft has found another handy use for the principle. Its patent describes a device in which a hologram sits on a spring and the information is read from it by a sensor at a fixed angle.

One possible application of the holographic accelerometer, Microsoft says, could be adding accelerometer controls to a portable computer. Giving your machine a quick shake could start up a particular program or jump between applications. (ANI)