Pacemakers that run on light

时间:2019-03-07 07:16:00166网络整理admin

By Peter Hadfield PEOPLE with pacemakers face surgery every five to ten years to replace their worn-out batteries. Researchers at Osaka University in Japan hope to avoid this by building in a battery that can be recharged through the patient’s skin. The prototype pacemaker measures 40 millimetres by 30 millimetres by 5 millimetres and is attached to a solar cell 20 millimetres square. The researchers implanted the pacemaker in a mouse, with the solar cell 5 millimetres under the animal’s skin. Shining a beam of laser light onto the skin charged up the battery. Because skin absorbs visible light, the researchers used near-infrared light with a wavelength of around 860 nanometres. Skin is transparent at this wavelength. The light was generated by the same type of laser used in CD players. A two-hour charge kept the battery going for 22 hours. “Using the laser for two hours a day is not dangerous. The patient receives about 30 per cent of the safety limit of laser irradiation,” says Osamu Nakamura, one of the researchers. “But we’re trying to reduce the charging time.” Alternatively, the charger can be adapted so that a longer charge will last for a correspondingly longer time. There are around 200 000 people in Japan with pacemakers. The average age of these patients is falling, and with current technology their batteries would need to be changed several times in the course of a normal lifetime. The researchers say the system could be used for other internal medical devices that rely on battery power,