Marangoni rotor mini-generator

Matrix context

D = disequilibrium row · C = coupling family column. A cell reads the state of the atlas for that pair.

D.15 × C.34 · Surface energy difference × Marangonifamily: MarangoniD.15 × C.14 · Surface energy difference × Electromagnetic inductionfamily: Electromagnetic induction

Measured or reported performance

1. load voltage1.6 mV maximum across 35 Ωdevice2019
   permanent magnets on the rotor passing a stationary 800-turn copper coil (r = 35 Ω) connected to a 35 Ω resistor; about 7 × 10⁻⁸ W at the maximum — the power figure is derived from the reported voltage and resistance, not reported directly
   refs [4]

Steps

1. 01
   Surface energy difference —drives→ Marangoni effectestablishedclaim record

   surface → kinetic · loss to thermal

   • a gradient of surface tension along a free liquid interface, from composition (solutocapillary) or temperature (thermocapillary)

   liquid

   refs [1] [2]
2. 02
   Marangoni effect —produces→ Mechanical motionreplicatedclaim record

   kinetic → mechanical · loss to thermal

   • a floating or interface-bound body whose asymmetry (shape, or where it emits a surfactant or absorbs heat) leaves a net surface-tension force or torque on it
   • the body must be free to move on the interface; a rigid wall only sets up a flow

   liquid

   Two independent groups: thermocapillary microgears (Maggi et al. 2015, light-heated, up to 300 r.p.m.) and solutocapillary camphor rotors carrying magnets past a coil (Frenkel et al. 2019, 10–20 h). Distinct from Marangoni flow turning a rotor: here the Marangoni stress acts on the moving body directly.

   refs [3] [4]
3. 03
   Mechanical motion —drives→ Electromagnetic inductionestablishedclaim record

   mechanical → electrical · loss to thermal

   • a magnet moving relative to a coil

   conductor required · magnetic field required

   refs [5] [6]
4. 04
   Electromagnetic induction —produces→ Charge carriersestablishedclaim record

   electrical → electrical · loss to thermal

   refs [5] [7]
5. 05
   Charge carriers —converts into→ Electrical workestablishedclaim record

   electrical → electrical · loss to thermal

   • carriers driven through an external load at the potential difference the source maintains

   refs [8]

Evidence for the complete composition · 1

1. [4]
   M. Frenkel et al.. Mini-Generator of Electrical Power Exploiting the Marangoni Flow Inspired Self-Propulsion (2019)

   ACS Omega 4, 15265–15268 · doi:10.1021/acsomega.9b02257 · record

Evidence for the constituent relations · 8

1. [1]
   L. E. Scriven, C. V. Sternling. The Marangoni Effects (1960)

   Nature 187, 186-188 · doi:10.1038/187186a0 · crossref ✓ 2026-09-20 · record
2. [2]
   Q. Dai et al.. Directional interfacial motion of liquids: Fundamentals, evaluations, and manipulation strategies (2021)

   Tribology International 154, 106749 · doi:10.1016/j.triboint.2020.106749 · crossref ✓ 2026-09-20 · record
3. [3]
   C. Maggi et al.. Micromotors with asymmetric shape that efficiently convert light into work by thermocapillary effects (2015)

   Nature Communications 6, 7855 · doi:10.1038/ncomms8855 · record
4. [4]
   M. Frenkel et al.. Mini-Generator of Electrical Power Exploiting the Marangoni Flow Inspired Self-Propulsion (2019)

   ACS Omega 4, 15265–15268 · doi:10.1021/acsomega.9b02257 · record
5. [5]
   M. Faraday. Experimental researches in electricity (1832)

   Philosophical Transactions of the Royal Society 122, 125–162 · doi:10.1098/rstl.1832.0006 · crossref ✓ 2026-09-19 · record
6. [6]
   S. P. Beeby, et al.. A micro electromagnetic generator for vibration energy harvesting (2007)

   Journal of Micromechanics and Microengineering 17, 1257 · doi:10.1088/0960-1317/17/7/007 · crossref ✓ 2026-09-19 · record
7. [7]
   L. D. Landau, E. M. Lifshitz, L. P. Pitaevskii. Electrodynamics of Continuous Media (Course of Theoretical Physics, Vol. 8, 2nd ed.) (1984)

   Pergamon · book, no DOI · record
8. [8]
   N. W. Ashcroft, N. D. Mermin. Solid State Physics (1976)

   Holt, Rinehart and Winston · book, no DOI · record