The outlook for new technology

Methanol fuel cells hold promise as power sources for portable gadgets. However, their low power, bulk, and high cost, as well as the fact that they spit out water vapor as a byproduct, have held back these cells' acceptance. Neah Power Systems claims to have overcome these problems with a fuel-cell technology based on porous silicon (Picture). Compared with traditional approaches, the use of a porous structure greatly increases the surface area in contact with the methanol, resulting in power density as much as three times better than current lithium-ion batteries. Moreover, the company's design seals both the fuel and the water-vapor waste in a disposable package. Eventually, Neah expects to deliver fuel cells that fit inside notebook-PC battery compartments, cost $2 or $3, and provide 120 Whr of power—enough for eight hours of operation.

Measuring the temperature of a body of water may be a trivial task up close, but it becomes difficult from a remote platform, such as a satellite. An instrument pointed at the body picks up not only the water's thermal signature, but also unwanted reflected radiation, such as sunlight. Researchers at the Stennis Space Center have proposed an infrared sensor that overcomes this problem by exploiting water's polarization characteristics (Picture). The innovation rests on the Brewster angle—the angle at which light that's polarized parallel to the plane of incidence on a dielectric material is not reflected. Scientists would aim an infrared radiometer with a polarizer at a body of water using an angle of incidence equal to the Brewster angle (around 51°). Even though water is not a perfect dielectric, the radiation reaching the instrument would consist almost entirely of thermal emission from the water's surface.

The SnifferSTAR, a half-ounce sensor platform from Sandia National Laboratories and Lockheed-Martin can detect nerve gases and blister agents from its perch on a small drone aircraft. The forward motion of the drone forces air into the device and passes it over thin strips of material on a quartz surface. When particles stick to the strips, they alter the frequencies at which the quartz vibrates when an electrical current stimulates it, creating a recognizable pattern that users can compare to a library of samples. The drone can either hold the data for later evaluation or send them via a radio link for immediate analysis. The credit-card-sized device operates on only 0.5W.

In an example of the increasingly common cross-fertilization between the semiconductor industry and biology, scientists at Cornell University have created a microchip that allows them to optically isolate individual biological molecules. The chip features 2 million waveguides, or "holes," as small as 40 nm across. Because their openings are one-tenth as big as the wavelength of light, the waveguides prevent most of the light a laser generates from reaching a sample liquid contained in the holes. However, a few photons do penetrate a short distance into the waveguides, and this illumination allows the researchers to observe the interaction between a fluorescently tagged DNA molecule and an enzyme. The innovation may prove useful in drug discovery and DNA sequencing.