Building a Better Biosensor

Courtesy of Michael J. Sailor

imparts a rainbow of colors to a porous silicon chip, one of a variety of new biosensor technologies in development around the world. The different colors correspond to different sized pores, ranging from a few nanometers to hundreds of nanometers in diameter. These pores help the device discriminate and detect proteins and other molecules based on their size.

One morning in March 1995, the deadly nerve gas sarin wafted through the Tokyo subway system. Six years later, spores of lethal Bacillus anthracis turned up in the US Postal System (USPS). Then in February, ricin, a toxin derived from castor beans, appeared in the mailroom of Senate Majority Leader Bill Frist's office. The total human toll: 15 dead and more than 6,000 injured.

It is the evident ease with which these three attacks were carried out that has security personnel around the world on edge. And ...