Bimetallic-strip piezoelectric harvester

Matrix context

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

D.01 × C.08 · Temperature gradient × Heat engine (thermomechanical)family: Heat engine (thermomechanical)D.01 × C.10 · Temperature gradient × Piezoelectricfamily: Piezoelectric

Measured or reported performance

Summary figures only; no datum-level record yet. Each figure below is a reviewed summary, not a single measurement.

notes

microwatt-scale electrical output per snap in laboratory devices; the strip's snap-through converts a slow thermal cycle into an impulse the piezoelectric element can use

Typed bounds on this route

Every limit the atlas holds for this route, as constraint records: reached through bounded_by claims on the route's own entities. Hard bounds (an upper bound or a formula) decide the thermodynamic-bound check above; benchmarks, constitutive relations and resource limits are listed and never decisive. No prose limit exists anywhere (pass 42).

• Carnot limit · formula-bound · hard, applies to this route
  η ≤ 1 − T_c/T_h for any heat engine between reservoirs at T_h and T_c
• Electromechanical coupling factor · formula-bound · hard, applies to this route
  converted fraction per cycle ≤ k² = d²/(s·ε)

Steps

1. 01
   Temperature gradient —drives→ Thermal expansionestablishedclaim record

   thermal → mechanical

   refs [1] [2]
2. 02
   Thermal expansion —produces→ Mechanical stress or strainestablishedclaim record

   mechanical → mechanical

   • non-uniform thermal expansion is mechanically incompatible across adjacent regions of a solid, or is constrained by an adjoining material or structure, producing a strain or stress gradient; the constraining region may be the cooler part of the same continuous specimen rather than a separate stiffer body

   solid

   refs [3] [2]
3. 03
   Mechanical stress or strain —drives→ Direct piezoelectric effectestablishedclaim record

   mechanical → electrical · loss to thermal

   D = d · σ · piezoelectric charge coefficient d [C/N]

   • a non-centrosymmetric crystal or a poled ferroelectric ceramic or polymer
   • stress below the depoling and fracture limits

   solid · non-centrosymmetric crystal required

   refs [4] [3] [5]
4. 04
   Direct piezoelectric effect —produces→ Separated surface chargeestablishedclaim record

   electrical → electrical

   refs [3]
5. 05
   Separated surface charge —converts into→ Electrical workestablishedclaim record

   electrical → electrical · loss to thermal

   • electrodes on the charged surfaces connected through a load

   refs [6]

Evidence for the complete composition · 1

1. [7]
   J. Boughaleb et al.. Coupling of a bimetallic strip heat engine with a piezoelectric transducer for thermal energy harvesting (2016)

   Molecular Crystals and Liquid Crystals 628, 15–22 · doi:10.1080/15421406.2015.1137390 · crossref ✓ 2026-09-20 · record

Evidence for the constituent relations · 6

1. [1]
   A. Bejan. Advanced Engineering Thermodynamics (4th ed.) (2016)

   Wiley · doi:10.1002/9781119245964 · crossref ✓ 2026-09-19 · record
2. [2]
   S. Iwakiri, Y. Miyata, T. Mori. Observation of universal thermopolarization effect in insulators (2026)

   arXiv:2605.17224 (17 May 2026), National Institute for Materials Science, Tsukuba · arxiv.org/abs/2605.17224 · record
3. [3]
   J. F. Nye. Physical Properties of Crystals: Their Representation by Tensors and Matrices (1985)

   Oxford University Press · book, no DOI · record
4. [4]
   J. Curie, P. Curie. Développement par compression de l'électricité polaire dans les cristaux hémièdres à faces inclinées (1880)

   Bulletin de la Société minéralogique de France 3, 90–93 · doi:10.3406/bulmi.1880.1564 · crossref ✓ 2026-09-19 · record
5. [5]
   A. Erturk, D. J. Inman. Piezoelectric Energy Harvesting (2011)

   Wiley · doi:10.1002/9781119991151 · crossref ✓ 2026-09-19 · record
6. [6]
   H. B. Radousky, H. Liang. Energy harvesting: an integrated view of materials, devices and applications (2012)

   Nanotechnology 23, 502001 · doi:10.1088/0957-4484/23/50/502001 · crossref ✓ 2026-09-19 · record