The floors have ears. Biomedical engineer Majd Alwan and his colleagues at the University of Virginia have developed a device that analyzes the footstep patterns of the elderly to detect falls and give early warning of certain diseases. Unlike monitors that require users to wear sensors, walk on special platforms, or be videotaped, this device sits on the floor unobtrusively. The brick-size box contains a sensor that measures tiny vibrations and a microprocessor that learns a person's normal walking habits and uses signal-processing algorithms to detect changes. If the person falls, or limps or shuffles-warning signs of diseases such as osteoarthritis or Parkinson's-the monitor alerts a computer to send a message to a caregiver. The goal, says Alwan, is to "bring gait analysis out of the lab and into the home." His team recently spun off a company to commercialize the device, which could be placed in homes and assisted-living facilities within a year.

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