Expect more healthcare wearables that power themselves, many even managing with no battery. IDTechEx report, «Energy Harvesting for Electronic Devices 2020-2040» covers this and more. The primary toolkit is five ways of taking ambient energy to make electricity. Improved photovoltaics PV – solar cells – doubling the amount of electricity they produce, thermoelectrics TE now able to convert even small temperature differences, electrodynamics ED as tiny rotary and linear generators, piezoelectrics PZ grabbing pressure or movement and new kid on the block – triboelectric nanogenerators TENG soon in the market making electricity from induction from moving static charge induced by contact. Consider ED. Many infants, especially in under-resourced settings across Africa suffer brain injury or die from inadequate oxygen during labour but now wind-up Doppler ultrasound monitors monitor labour.
Flexible laminar forms and combinations are coming in fast. The new Matrix smart watch measuring many fitness and medical parameters combines PV and TE. Others use a swinging weight powering ED inside as do several self-powered smart products for monitoring and control purposes. Full-function energy-independent smart watches come next, paving the way for many dedicated medical devices. GeorgiaTech even researches Self-Charging Power Cells SCPC for charging medical devices. They combine lithium batteries, TE and/or PZ film in one smart material.