Tiny devices such as contact and temperature sensors or for weather measurement and automation are spreading rapidly. The power supply requires cables or batteries, which a new type of energy cell could change.https://www.notebookcheck.net/Heat-pump-on-the-wrist-chip-converts-heat-into-electricity-for-IoT-and-sensors.830159.0.html
Whoever made that photo and decided to include it in the article, should be fired.
Bad conversion. You say 100 microjoules is 0.001 watt*hours. But the conversion rate 3.6 billion microjoules to one watt*hour. So 100 microjoules is around 0.0000000277 watt*hours. Or 0.0277 microwatt*hours.