FactReactorBone Is Piezoelectric, Like A Gas Lighter
Watch on YouTubeThe bone in your thigh is not an inert beam. Load it - stand, step, jump - and a small voltage appears across it.
Two things produce that voltage. The collagen fibres that form bone's organic scaffold are piezoelectric: shear them and charge shifts across them. Yasuda reported it in dry bone in 1954, and Fukada and Yasuda confirmed it in 1957. In wet, living bone, though, the larger share comes from something else - fluid pushed through the bone's microscopic canals past charged walls, a streaming potential.
The collagen half is the same physics that makes the spark in a push-button lighter. The lighter uses a ceramic. Your skeleton uses a protein it built itself.
Whether these voltages help decide how bone rebuilds itself under load is still a hypothesis, not a settled fact.
Sources:
https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.705199/full
https://pmc.ncbi.nlm.nih.gov/articles/PMC9243952/
https://pmc.ncbi.nlm.nih.gov/articles/PMC5828134/
Original paper: E. Fukada and I. Yasuda, J. Phys. Soc. Jpn. 12, 1158 (1957)
Clarification
Four things 50 seconds could not hold. 1. In wet, living bone most of the voltage from a step is not the collagen. It is a streaming potential: fluid forced through tiny canals past charged walls. Collagen piezoelectricity is real and has been measured since the 1950s - it is the smaller share. That is why the video names both. 2. Does that voltage tell your bones where to get stronger? Maybe. It is a serious hypothesis and still not established. Anyone selling you denser bones through "the piezoelectric effect" is ahead of the evidence. 3. Most push-button lighters use a ceramic called PZT, not protein and usually not quartz. Same effect, a much stronger material. 4. Yes, the twisted strand in the lighter scene looks like DNA. Collagen is a helix too - a triple one, three protein chains wound together. More videos on the physics your body is quietly doing are on the way. Which part of your body do you suspect is secretly doing physics?