Chemist Matthew Cooper and his colleagues at Cambridge University have devised a quick and efficient way to detect diseasesby sound. The researchers fashioned an acoustic virus detector from a set of metal-covered quartz-crystal disks, each about one-fifth the size of a dime, coated with compounds that stick to one particular type of virus. A drop of possibly infected fluid is placed on the disk. Any viruses in the drop bind to the surface of the disks. Then the disks are washed and exposed to electric current, which causes the quartz crystals to vibrate millions of times per second. These violent motions shake off the viral particles, which make a popping sound as they detach. The crystal acts as a microphone to detect the sound, which reveals that the viruses are present and determines the intensity of the infection. The procedure takes about an hour, far less time than other techniques for diagnosing infection.
In tests, the sound detector successfully found herpes viruses in a salt-water solution. Cooper and his team are now working to adapt it so it can diagnose HIV and hepatitis B viruses, or even bacteria, from a blood sample. Paul Parren, an immunologist at Scripps Research Institute in California, thinks this approach is very promising. "It's cheap, fast, and very specific and sensitive," he says.