An implantable power supply with an optically rechargeable lithium battery

A novel power supply for medical implants has been developed. A wireless near-infrared power transmission recharges a lithium secondary battery in the power supply. A photovoltaic cell array embedded under skin receives near-infrared light through the skin and charges the battery directly powering an implanted device. The authors have shown that, for a photodiode area of 2.1 cm ², 17 min of near-infrared irradiation at a 810-mn wavelength with a power density of 22 mW/cm ² can send enough energy to allow regular commercial cardiac pacemakers to run for 24 h. The temperature rise of the skin during the light irradiation was 1.4°C.