Physical Transformation AtlasPTA
Pathway · p-423a19acdd · candidate

Thermocapillary streaming-potential generator (proposed)

Temperature gradientMarangoni effectFluid flowStreaming potentialIonic currentElectrical work

A temperature gradient along a free electrolyte surface drives a thermocapillary shear flow past a charged wall, whose streaming potential is the electrical output. Analysed theoretically and numerically; no physical demonstration is recorded, so the route stays a candidate.

Epistemic state of the route

known constituent relations
5 / 5 established or replicated · weakest constituent replicated
constituent maturity floor
K4 · experimentally observed
search for this exact route
Exact composition search: reviewed 2026-09-21 — partial; No physical demonstration of temperature gradient → Marangoni flow → streaming potential → electrical output was found in the OpenAlex protocol runs, the two citation chases or the four Google Scholar forms run by hand on 21/09/2026 (Scholar's full-text index screened at the protocol depth). The route's only literature is the Pini 2015 theoretical proposal and its 2011 precursor; the solar-evaporator hydrovoltaic papers that invoke a thermal Marangoni flow use it as a co-driver or enhancer of an evaporation-driven streaming output and never isolate its contribution (parallel-driver rule: driver-only-modifies); the thermocapillary micro heat engine converts the droplet motion through a piezoelectric membrane, a different second mechanism. Inconclusive until the Semantic Scholar runs exist and the two unread chase hits are read.
recorded pathway
Thermocapillary streaming-potential generator (proposed) · proposed in the literature, not demonstrated — a proposal in the literature, not a demonstration; the route stays a candidate and its search state is unchanged by the proposal
composition maturity
K3 · theoretically quantified
recorded-pathway overlap
none recorded
route-level evidence
1 source for the complete composition · 6 cited by the constituent steps
boundaries and interfaces
BOUNDARY compatible · no region transition

Explorematrix context · physics checks · performance · steps · route evidence · constituent evidence · cite

Matrix context

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

D.01 × C.34 · Temperature gradient × Marangonifamily: MarangoniD.01 × C.23 · Temperature gradient × Electrokineticfamily: Electrokinetic

Literature search for this exact composition

Reviewed search · 2026-09-21OpenAlex + Google Scholarpartial

No physical demonstration of temperature gradient → Marangoni flow → streaming potential → electrical output was found in the OpenAlex protocol runs, the two citation chases or the four Google Scholar forms run by hand on 21/09/2026 (Scholar's full-text index screened at the protocol depth). The route's only literature is the Pini 2015 theoretical proposal and its 2011 precursor; the solar-evaporator hydrovoltaic papers that invoke a thermal Marangoni flow use it as a co-driver or enhancer of an evaporation-driven streaming output and never isolate its contribution (parallel-driver rule: driver-only-modifies); the thermocapillary micro heat engine converts the droplet motion through a piezoelectric membrane, a different second mechanism. Inconclusive until the Semantic Scholar runs exist and the two unread chase hits are read.

11 runs · 5 attempts blocked before any result (Semantic Scholar, Google Scholar) — attempted, never counted · 161 unique records · 4 read in full · reviewed by Ava Kim's loop-3 lane · protocol route-search-v1
  • Energy conversion by surface-tension-driven charge separation (2015) · theory only · Pini, Baier & Dietzel analyse the streaming potential of thermocapillary and destillocapillary free-surface flows analytically and numerically (arXiv 1609.09404 read in full); no experiment is reported. Recorded as the route's proposed pathway.
  • Electro-Marangoni Effect in Thin Liquid Films (2011) · wrong coupling · Film drainage (not a temperature gradient) drives the liquid outflow that generates a streaming potential; the Marangoni effect is the reverse surface flow the potential produces. The chain runs drainage → streaming potential → electro-Marangoni, the opposite order to the route (abstract).
  • Thermocapillary convection during hydrogen evolution at microelectrodes (2019) · constituent only · Ohmic heating at a Pt microelectrode sets up a temperature gradient whose thermocapillary stress drives electrolyte flow at hydrogen bubbles; velocity and temperature fields are measured (PTV, luminescence lifetime imaging). Temperature gradient → Marangoni flow is demonstrated; no streaming potential or current is measured (abstract).
  • Particle migration in suspensions by thermocapillary or electrophoretic motion (1990) · wrong coupling · Two mathematically analogous problems (thermocapillary bubble migration; electrophoresis of colloids) treated in parallel; thermocapillary flow does not generate the electrokinetic response (abstract).
  • Heat transfer enhancement driven by thermo-electro-hydrodynamics (TEHD): Influence of the Marangoni effect (2026) · wrong coupling · Title: an applied electric field drives the flow (electrohydrodynamics) with the Marangoni effect as a modifier; the electrical side is the driver, not an output. Not read beyond the title.
  • Gradient architecture solar evaporator for efficient hypersaline wastewater treatment and freshwater-salt-electricity Trigeneration (2025) · driver only modifies · Thermal Marangoni/thermocapillary circulation manages salt transport in a solar evaporator, while the reported electrical potential (0.3 V open-circuit over 10 h) is attributed to the engineered salt/ionic gradient; no Marangoni-attributable streaming output is isolated (abstract read on the publisher's page).
  • A 3D fabric evaporator with yarn arrays enables sustainable salt-resistant desalination and electricity generation (2025) · driver only modifies · Thermocapillary force is an auxiliary transport mechanism inside an evaporation-driven hydrovoltaic device (0.503 V); no control resolves its contribution to the output (abstract read; the Marangoni discussion is in the text).
  • Layered 3D aerogel evaporator with bioinspired architecture for high-performance solar desalination (2026) · driver only modifies · The paper's own wording — a thermal Marangoni flow 'amplifies the resulting streaming potential' — makes it an enhancer/co-driver of an evaporation-driven output, not an isolated D → M1 → M2 demonstration (Scholar snippet; journal version J. Environ. Chem. Eng. 2026, not read).
  • Achieving Ultrahigh Voltage Over 100 V and Remarkable Freshwater Harvesting Based on Thermodiffusion Enhanced Hydrovoltaic Generator (2024) · driver only modifies · Thermo-capillary convection occurs inside a thermodiffusion/evaporation hydrovoltaic system (45.6 μW cm⁻²; 105 V from 192 units), but the electrical output is not experimentally decomposed into a Marangoni-driven component (abstract read on OpenAlex).
  • Synergistic interfacial evaporation and electricity generation enabled by Fe–Co PBA derived natural sponges (2026) · driver only modifies · Marangoni transport is invoked within coupled interfacial-evaporation and moisture electricity generation without isolation of the Marangoni → streaming contribution (one-sentence publisher abstract and Scholar snippet).
  • Chemical-Gradient-Induced Marangoni Flows Boost Solar-Brine Desalination and Enable Concurrent Power Generation (2026) · driver only modifies · A solutocapillary co-driver, relevant to the sibling route p-41cb505083 (surface energy difference → Marangoni → streaming), where it is recorded: a programmed surface-tension gradient sustains Marangoni microcirculation alongside capillary flow in a hydrovoltaic evaporator (25 μA, 0.7 V, an LED lit) without isolating the Marangoni branch. For this thermal route it is the wrong driver (abstract read on OpenAlex).
  • Recent advances in nano-electromechanical and microfluidic power generation (2006) · constituent only · Thermocapillary droplet pumping supplies mechanical pressure/deformation to a piezoelectric converter rather than a streaming-potential stage; evidence for the target M1 with a different downstream conversion. The primary experimental paper is Odukoya & Naterer 2013 (IJHMT 58:202, read in full): the micro heat engine was fabricated on PZT with Ti-W microheaters, the droplet pumping was measured, and the 1.2–1.3 mV and ≈ 1.6 % are simulation results — a search/pathway target for Temperature gradient → thermocapillary pumping → mechanical stress → piezoelectric effect → electricity, not for this route (abstract read).
  • Field-enhanced electrokinetic charge separation induced by thermocapillarity-driven flow in a liquid film (2011) · theory only · APS DFD 2011 abstract: thermocapillary stresses in a thin liquid film in a lateral thermal gradient induce a streaming potential through the electrokinetic effect, with the upper limit of the streaming potential derived — the theoretical precursor of Pini 2015; no experiment (title and meeting abstract only).
  • Hydroelectric power plant on a paper strip (2018) · wrong driver · Capillary wicking through paper drives the flow whose streaming potential is harvested; a surface-tension-driven imbibition with no surface-tension gradient, so not the Marangoni effect. Caught by the alias 'surface-tension-driven flow', which pass 22 removed from the phenomenon (Scholar snippet; not read).
Limitations: Semantic Scholar runs not made (anonymous API pool answered HTTP 429 throughout; key requested from the owner, exception e953), mandatory for a negative; Google Scholar's four forms were run by hand on 21/09 as compact strings (Scholar's ~32-word limit) — see the run notes OpenAlex driver-mechanism query: 1,393 works reported, the first 100 by relevance and the first 50 newest screened at title level (protocol depth), the rest unscreened citation chase done on OpenAlex's reference lists and citing works only (Pini 2015: 40 references, 3 citers; Massing 2019: 54 references, 101 of 103 citers), screened at title level with an electrokinetic/electrical vocabulary filter; no full-text chase the mechanism-pair, whole-chain and demonstration-precision queries returned 2, 0 and 0 works Google Scholar: the driver-mechanism form reports about 19,200 works, of which the first 100 by relevance were screened at title level (protocol depth); the mechanism-pair form 282, the first 100 screened; Scholar's full-text index surfaces papers that only mention the mechanisms in passing, so its lists are noisier than OpenAlex's the two Elsevier chase hits (Ruckenstein 1981; Pal et al. 2011) remain unread pass 49 (21/09 ~11:29 pm Sydney): every planned Semantic Scholar query was attempted once through the anonymous pool — 4 of 4 answered HTTP 429 at the first request (the runs above, each with its literal query, key and time); Google Scholar served its bot check at the first load of the driver-mechanism form (recorded as an attempt with nothing screened). Both engines are mandatory for a negative under route-search-v1, so the record stays partial and inconclusive: the outstanding obligations are the Semantic Scholar runs for every mandatory key and the Google Scholar runs to the protocol depth; OpenAlex's forms are complete. A blocked request is evidence that an engine was attempted, never that its query returned nothing.
Index query only · 2026-09-20OpenAlex · 5 queriesnot reviewed

2788 indexed works reported across the queries, 152 unique retrieved; nobody has read them for a qualifying demonstration. A person can screen this frozen list and promote it to a reviewed record without re-running the query.

  • OAdriver-mechanism:11393 reported · 100 retrieved
  • OAdriver-mechanism:11393 reported · 50 retrieved
  • OAmechanism-pair:1-22 reported · 2 retrieved
  • OAwhole-chain0 reported · 0 retrieved
  • OAdemonstration-precision0 reported · 0 retrieved

Planned runs NOT run in this bundle (engine unavailable): search:2026-09-20-p-423a19acdd/s2-dm1 (semantic-scholar); search:2026-09-20-p-423a19acdd/s2-mp12 (semantic-scholar); search:2026-09-20-p-423a19acdd/s2-wc (semantic-scholar); search:2026-09-20-p-423a19acdd/s2-dp (semantic-scholar).

Protocol route-search-v1: a frozen index run changes only the search state; only a reviewed record can say that a demonstration was or was not found.

Measured or reported performance

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

notes
Pini, Baier and Dietzel (2015) compare the maximal thermal efficiency of the thermocapillary drive with the Carnot value and find it limited by the heat capacity of aqueous solvents — the source's own analysis, not a bound of the atlas.

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
  • Onsager–Casimir reciprocity · constitutive-relation · listed, never decisive
    L_ij(B) = ε_i ε_j L_ji(−B): the cross-coefficients of coupled linear transport are equal up to the time-reversal parities ε of the variables and reversal of the magnetic field; L_ij = L_ji is the zero-field, even-parity case

Steps

  1. 01
    Temperature gradient —drives→ Marangoni effectestablishedclaim record
    thermal → kinetic · loss to thermal
    • thermocapillary case: surface tension falls with temperature, so a temperature gradient along the interface drives flow toward the cold side
    liquid · temperature gradient required
    refs [1] [2]
  2. 02
    Marangoni effect —produces→ Fluid flowestablishedclaim record
    kinetic → kinetic
    refs [1] [2]
  3. 03
    Fluid flow —drives→ Streaming potentialreplicatedclaim record
    kinetic → electrical · loss to thermal
    • the produced liquid flow passes a charged surface or through a charged channel; the charged boundary is a condition of the step
    • not something the upstream flow provides
    aqueous medium required · bulk flow required · charged surface required
    refs [3] [4]
  4. 04
    Streaming potential —produces→ Ionic currentestablishedclaim record
    electrical → electrical
    refs [4] [5]
  5. 05
    Ionic current —converts into→ Electrical workestablishedclaim record
    electrical → electrical · loss to thermal
    • electrodes exchange the ionic current for an electronic current through the external load
    refs [6]

Evidence for the complete composition · 1

  1. [7]
    C. Pini, T. Baier, M. Dietzel. Energy conversion by surface-tension-driven charge separation (2015)
    Microfluidics and Nanofluidics 19, 721–735 · doi:10.1007/s10404-015-1597-x · record

Evidence for the constituent relations · 6

  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]
    J. Yin, et al.. Generating electricity by moving a droplet of ionic liquid along graphene (2014)
    Nature Nanotechnology 9, 378–383 · doi:10.1038/nnano.2014.56 · crossref ✓ 2026-09-19 · record
  4. [4]
    J. Yang et al.. Electrokinetic microchannel battery by means of electrokinetic and microfluidic phenomena (2003)
    Journal of Micromechanics and Microengineering 13, 963 · doi:10.1088/0960-1317/13/6/320 · crossref ✓ 2026-09-19 · record
  5. [5]
    R. J. Hunter. Zeta Potential in Colloid Science: Principles and Applications (1981)
    Academic Press · doi:10.1016/C2013-0-07389-6 · crossref ✓ 2026-09-19 · record
  6. [6]
    A. J. Bard, L. R. Faulkner. Electrochemical Methods: Fundamentals and Applications (2nd ed.) (2001)
    Wiley · book, no DOI · record

Cite this route

Physical Transformation Atlas (2026). route p-423a19acdd: Thermocapillary streaming-potential generator (proposed). Dataset revision rbfbfcbb70e57 (hash of the canonical data). https://physical-transformation-atlas.wldud5192.workers.dev/path/423a19acdd

Ids and matrix addresses are stable across revisions; the revision hash identifies the exact canonical files the record was compiled from and is meta.data_hash in every /api export. Reuse terms: see the license field in any export.