# Micro energy harvesting

Devices that gather tiny amounts of power from motion, heat, friction, radio waves or humidity.

Source page: https://www.materialinsights.org/energy/e_micro_harvest/

Capture · Emerging · No. 48

- Capture
- Output: Small amounts of electricity
 Capture · Emerging · Foundation · Energy

A wristwatch powered by body heat converts just 0.1% of the warmth flowing through it, enough for 22 microwatts.

Chart: Illustration: Micro energy harvesting

##### Where it comes from

Footsteps, vibration, body heat, radio signals and even damp air all carry stray energy. Crystals, semiconductors, antennas and films catch a trickle of it, from microwatts to watts.

Pavegen has over 250 floor-tile installations, Betavolt sells a 100-microwatt nickel-63 cell and NASA flies plutonium RTGs; the whole market was about USD 0.61 billion in 2025.

##### Three things to know

1. A road harvester in a California test captured about 10% of passing vehicles' motion, some 7 to 17 J per vehicle.
2. NASA's MMRTG turns plutonium-238 decay heat into about 110 W at launch, falling to about 72 W after 17 years.
3. A film of bacterial protein nanowires can draw electricity from humid air, at most about 8.5 microwatts per cm².

##### The journey

1. 1 **Ambient energy**Motion, heat, radio waves or moisture
2. 2 **Harvester**Crystal, semiconductor, antenna or film
3. 3 **Conversion**Tiny voltage rectified by a circuit
4. 4 **Storage**Capacitor or battery holds the trickle
5. 5 **Use**Sensors, wearables, tags and space probes

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## Other sections

- [Overview](https://www.materialinsights.org/energy/e_micro_harvest/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_micro_harvest/correlation/index.md)
- [Efficiency](https://www.materialinsights.org/energy/e_micro_harvest/efficiency/index.md)
- [Techniques](https://www.materialinsights.org/energy/e_micro_harvest/techniques/index.md)
- [Resources and labour](https://www.materialinsights.org/energy/e_micro_harvest/resources/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_micro_harvest/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_micro_harvest/links/index.md)