Biophan Technologies is developing an implantable power source that recharges an implant’s batteries using electricity generated by the patient’s own body heat.

The “biothermal battery” uses arrays of thousands of thermoelectric generators. Biophan plans to produce an array 2.5 centimetres square that generates 4 volts and delivers a power of 100 microwatts.

The technology would require fewer surgical procedures, which are stressful and carry the risk of infection.