The microscopes that look at tiny things, like living cells, tend to be bulky items themselves. Not so a device created by bioengineer Luke Lee at the University of California, Berkeley. In his microscope, a sample cell is dropped into a liquid-filled channel etched into a chip, where it gets tagged by a fluorescent dye and is illuminated by a tiny laser. This beam prompts the dye to glow at a specific wavelength, resulting in a sharp image of the cell. The laser’s lens is a droplet of liquid polymer one-20th the diameter of a hair; it is focused by application of an electric current that changes its curvature. The microscope uses cheap components and could be fabricated the same way that microchips are made, at a cost of about $1 each. Lee believes that this microscope, funded by the U.S. Defense Advanced Research Projects Agency, will in three to five years show up in a wristwatch-sized biowarfare monitoring computer. Pharmaceutical companies could use arrays of the microscopes to study the effects of experimental drugs.