Lighting Ballasts That Direct Patients

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The system can be customized to particular users. Depending on their stage of recovery, some brain-trauma patients might need more or less frequent instructions, or they might need to start out with a reminder to put on a helmet or check their shoelaces. Family members can make the audio recordings so that patients can hear a trusted voice, and the recordings can be in any language. User data is recorded during use and analyzed afterward to assess each patient's progress--how many reminders he needed, how much time it took him to reach his destination--and the system is adjusted accordingly.

"The brain is a dynamic organ," says Chae. "The whole basis of rehab is repetition of voice commands and tasks." He believes that the system helps patients learn to adapt to unfamiliar places, and so ultimately, it could benefit the patient outside the hospital, too, by retraining his or her brain.

Leeb and Lupton say that their system processes users' locations more quickly and accurately than do other systems that rely on GPS, radio frequencies, or Wi-Fi triangulation. GPS doesn't work well in buildings, and it only has a resolution of about 30 feet, so it isn't ideal for guiding patients around a hospital. Systems that calculate location based on the local strength of Wi-Fi signals from transmitters in multiple locations require more time-consuming calculations than the lightbulb system does, and this could slow people down and drain the PDA's battery. Conversely, the resolution of Leeb and Lupton's system is limited only by the spacing of the light fixtures. (Signals from the Talking Lights system don't interfere with hospital equipment, much of which is shielded.)

The company is currently developing a system that connects to a robust Wi-Fi mesh network to deliver information about patients' locations to hospital staff. Nurses monitoring people with dementia in an assisted-living facility, for example, could be quickly alerted when a patient wanders into an area that poses a fall risk. Talking Lights will demonstrate this monitoring capability in an Alzheimer's facility in a few months, says Leeb. The company has also installed a system for the blind in Stanford University's department of psychology.

In the coming years, Talking Lights plans to develop software that can run on smart phones and hardware for a Bluetooth headset with an optical receiver. The headset would pick up the optical signals, send them to the phone, and then play back directions to the wearer.