MESSAI.iO

Reproducibility · ISMET EU 2026

Five-parameter minimum checklist

Reporting these five experimental parameters reduces inter-study power-density variance by more than 40% (487 → 278 mW/m², p < 0.05) across 63 validation papers from the MESSAI corpus.

Score your own paper, browse the 289-paper corpus distribution, or use the comprehensive 18-parameter view for a deeper audit.

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Interactive scorer

Toggle each criterion to see how your reporting compares against the ISMET 2026 minimum. Each criterion links to the literature it’s grounded in.

Electrode Spacing

Cell GeometryCriticalcm

Distance between anode and cathode electrodes (cm). Controls ohmic resistance and mass-transport boundary layer thickness; the single largest determinant of power density variance across papers in the abstract's correlation analysis (r = 0.37).

Typical range: 1 – 20 cm

1 reference
  • Liu & Logan 2004 (Environ Sci Technol 38:4040)
Current status: Missing

Electrode Surface Area

Cell GeometryCriticalcm²

Projected geometric area of the anode and cathode (cm²). Required to convert raw current to areal current density. Without it, any power-density claim is a unit-less number — cross-study comparison becomes impossible.

Typical range: 1 – 1,000 cm²

1 reference
  • Logan 2008 (Microbial Fuel Cells, Wiley)
Current status: Missing

External Resistance

CircuitCriticalΩ

Load resistance across the circuit (Ω). Sets the operating point on the polarization curve. Maximum power is reported at R_ext = R_internal; papers omitting R_ext typically also omit polarization sweeps, making the reported power point uncomparable.

Typical range: 10 – 10,000 Ω

1 reference
  • Logan et al. 2006 (Environ Sci Technol 40:5181)
Current status: Missing

Measurement Method

MethodologyCritical

How power / current were measured: data-logger vs handheld multimeter, sample interval, voltage-sweep protocol if a polarization curve was run. 8% of inter-study variance in the abstract's correlation analysis. Without it, a 26 mW/m² instantaneous reading is indistinguishable from a 26 mW/m² 24-hour average — a 4× real-world performance gap masquerading as agreement.

1 reference
  • Logan et al. 2019 (Nat Rev Microbiol 17:307)
Current status: Missing

Unit Normalization Basis

MethodologyCritical

Whether power is normalized to electrode area (mW/m²), reactor volume (W/m³), or anode mass (W/kg). The abstract's headline finding: power density spans five orders of magnitude (CoV 1,285%) largely because authors silently change normalization basis. Stating it explicitly is the single highest-leverage reporting improvement (most extreme rows in the corpus collapse onto a ~10× range when re-normalized).

1 reference
  • Schröder 2007 (Phys Chem Chem Phys 9:2619)
Current status: Missing

ISMET 5-param minimum

0%

Not yet comparable

Fewer than 60% of criteria reported. The reported power / current numbers are not safely cross-comparable against the corpus — context is missing.

Reported
0
Omitted
0
Missing
5
Weighted score
0/5

Validation cohort

43% IQR reduction

Across 63 papers in the MESSAI corpus, those reporting all five minimum criteria had an inter-quartile range of 278 mW/m² on power density — vs 487 mW/m² for the rest.

Mann-Whitney U test, p < 0.05. Cohort defined by retrospective audit of the corpus against the checklist criteria; not a randomized trial.

Without checklist (n=46)487 mW/m²
With 5-param checklist (n=17)278 mW/m²

Axis: power-density inter-quartile range across each cohort, mW/m². Source: docs/abstracts/messai-eu-ismet-2026.pdf Figure 2C.

Corpus baseline

23.1% average completeness

Across 289 papers manually scored from the 10,824-paper indexed corpus, average reporting completeness is 23.1% — nowhere near the level needed for quantitative cross-study comparison.

MFC papers report on average 8.7 parameters; MEC papers report 3.6. MEC has the largest gap to close.

The five-parameter minimum is calibrated to be the lowest-friction subset that materially closes this gap.

SystemPapersElectrode
Specs		Operating
Conds		Electrical
Meas		BiologicalData
Reporting
MFC3,84772%58%45%35%32%
MES4,84268%55%42%32%28%
BES1,09665%48%38%28%25%
MEC96670%52%40%30%28%
MDC7355%38%28%20%15%

Heat scale: red < 20% · orange 20-35% · amber 35-50% · green 50-70% · deep green ≥ 70%. Source: abstract Fig 2A.

Coverage by experiment type

Reproducibility isn’t one number

Each study type needs a different minimum-reporting set, so we score each paper against its kind of study — a polarization curve, a continuous-flow treatment study, and a CO&sub2;-electrosynthesis run are judged on different criteria. Lower coverage = harder to reproduce.

Coverage:<15% critical15–35% partial>35% better

The dominant comparability gap

94.4% of papers reporting a power/current-density value never state which area it’s normalized to.

Areal vs volumetric — and which area (anode / cathode / membrane / projected) — differ by orders of magnitude; an unstated basis is the single biggest driver of the ~1,285% spread in reported power density.

When a basis IS stated: anode area 0.4% · electrode (generic) 0.1% · unspecified 99.4% · n = 1,363

Mean reporting coverage by study type, with the density normalization basis and the worst-reported criterion for each type.
Study typePapersMean coverageDensity basis statedWorst-reported criterion
Electrochemical characterization (polarization/CV/EIS/CA)1,96111.9%5.7%reference electrode (0.6%)
Modeling / simulation11313.6%13.5%model type (3.5%)
Treatment study (COD / nutrient removal)83217.1%11.4%duration (1.8%)
Startup / enrichment dynamics6126.6%3.4%startup time (4.9%)
Power-generation run1,68727.3%5.6%coulombic efficiency (2%)
Production / microbial electrosynthesis12229.7%9.6%duration (0.8%)
Materials / electrode screening33740.4%5.6%electrode area (13.1%)
Long-term stability4451.5%8.3%performance over time (36.4%)

Baseline comparability floor (% of all papers reporting)

  • 0.9% normalization basis
  • 1.8% buffer
  • 2.9% electrode spacing
  • 5.2% ionic conductivity
  • 9.5% ph
  • 9.6% electrode area
  • 13.1% substrate
  • 13.8% external resistance
  • 28.7% temperature

Local committed sample (papers with DOI + >=1 extracted param). Re-run against a full DB export for corpus-scale numbers. Method: scripts/analysis/experiment_type_coverage.py · generated 2026-06-18.

Comprehensive 18-parameter view

Importance-weighted scoring across reactor geometry, materials, substrate, biology, operating conditions, and performance metrics. Use this for a full reproducibility audit beyond the five-parameter minimum.

Cell Geometry

Electrode Spacing

Cell GeometryCriticalcm

Distance between anode and cathode electrodes (cm). Controls ohmic resistance and mass-transport boundary layer thickness; the single largest determinant of power density variance across papers in the abstract's correlation analysis (r = 0.37).

Typical range: 1 – 20 cm

1 reference
  • Liu & Logan 2004 (Environ Sci Technol 38:4040)
Current status: Missing

Electrode Surface Area

Cell GeometryCriticalcm²

Projected geometric area of the anode and cathode (cm²). Required to convert raw current to areal current density. Without it, any power-density claim is a unit-less number — cross-study comparison becomes impossible.

Typical range: 1 – 1,000 cm²

1 reference
  • Logan 2008 (Microbial Fuel Cells, Wiley)
Current status: Missing

Reactor Volume

Cell GeometryHighL

Total working volume of the bioelectrochemical system. Needed for volumetric power density calculation if that's the reported normalization basis.

Typical range: 0.01 – 1,000 L

1 reference
  • Logan et al. 2006
Current status: Missing

Circuit

External Resistance

CircuitCriticalΩ

Load resistance across the circuit (Ω). Sets the operating point on the polarization curve. Maximum power is reported at R_ext = R_internal; papers omitting R_ext typically also omit polarization sweeps, making the reported power point uncomparable.

Typical range: 10 – 10,000 Ω

1 reference
  • Logan et al. 2006 (Environ Sci Technol 40:5181)
Current status: Missing

Methodology

Measurement Method

MethodologyCritical

How power / current were measured: data-logger vs handheld multimeter, sample interval, voltage-sweep protocol if a polarization curve was run. 8% of inter-study variance in the abstract's correlation analysis. Without it, a 26 mW/m² instantaneous reading is indistinguishable from a 26 mW/m² 24-hour average — a 4× real-world performance gap masquerading as agreement.

1 reference
  • Logan et al. 2019 (Nat Rev Microbiol 17:307)
Current status: Missing

Unit Normalization Basis

MethodologyCritical

Whether power is normalized to electrode area (mW/m²), reactor volume (W/m³), or anode mass (W/kg). The abstract's headline finding: power density spans five orders of magnitude (CoV 1,285%) largely because authors silently change normalization basis. Stating it explicitly is the single highest-leverage reporting improvement (most extreme rows in the corpus collapse onto a ~10× range when re-normalized).

1 reference
  • Schröder 2007 (Phys Chem Chem Phys 9:2619)
Current status: Missing

Operating Conditions

Operating Temperature

Operating ConditionsHigh°C

Ambient or controlled-bath temperature. Drives the Arrhenius factor on biofilm kinetics and ohmic resistance.

Typical range: 15 – 35 °C

1 reference
  • Liu et al. 2005
Current status: Missing

Anolyte / Catholyte pH

Operating ConditionsHigh–

pH of each chamber. Sets Nernst potential offset + biofilm health envelope.

Typical range: 6.5 – 8.5

1 reference
  • Torres et al. 2008
Current status: Missing

Hydraulic Retention Time

Operating ConditionsHighh

For continuous-flow systems, the time a unit volume spends in the reactor (h). Identified in the abstract's analysis (8% impact) as the second most consequential underreported parameter after electrode spacing.

Typical range: 1 – 72 h

1 reference
  • Logan 2008
Current status: Missing

Materials

Anode Material

MaterialsHigh

Type and composition of the anode (carbon cloth, carbon felt, graphite brush, MXene-coated foam, etc.). Drives biocompatibility and electron-transfer kinetics.

1 reference
  • Wei et al. 2011
Current status: Missing

Cathode Material

MaterialsHigh

Type and composition of the cathode (Pt/C, MnO₂, air-cathode, biocathode). Dominates the oxygen-reduction overpotential.

1 reference
  • Rismani-Yazdi et al. 2008
Current status: Missing

Membrane / Separator

MaterialsHigh

Type of ion-exchange membrane or separator (Nafion 117, CEM, AEM, J-cloth, none). Sets ion transport resistance and crossover behaviour.

1 reference
  • Rozendal et al. 2006
Current status: Missing

Substrate

Substrate Type

SubstrateHigh

Carbon source: acetate, glucose, lactate, synthetic wastewater, real wastewater. Determines maximum theoretical electron yield and biofilm community.

1 reference
  • Logan 2009
Current status: Missing

Substrate Concentration

SubstrateHighg/L

Initial concentration of the organic substrate (mg/L or g/L COD). Sets the Monod saturation regime.

Typical range: 0.1 – 10 g/L

1 reference
  • Liu et al. 2004
Current status: Missing

Electrolyte Composition

SubstrateMedium

Buffer composition + ionic strength of anolyte / catholyte. Sets solution conductivity which appears in the ohmic resistance.

1 reference
  • Lovley 2006
Current status: Missing

Biological

Inoculum Source

BiologicalMedium

Source + type of microbial inoculum (anaerobic digester sludge, soil, defined pure culture). Drives biofilm community structure.

1 reference
  • Logan & Regan 2006
Current status: Missing

Startup Period

BiologicalMediumweeks

Time required for system startup + biofilm establishment (weeks). Without it, reported peak performance can be a transient overshoot vs steady state.

Typical range: 1 – 8 weeks

1 reference
  • Liu & Logan 2004
Current status: Missing

Performance

Coulombic Efficiency

PerformanceMedium%

Fraction of electrons recovered as current vs. those theoretically available from substrate oxidation. Closes the energy-balance loop alongside power density.

Typical range: 10 – 90 %

1 reference
  • Logan et al. 2006
Current status: Missing

Comprehensive (18-param)

0%

Not yet comparable

Fewer than 60% of criteria reported. The reported power / current numbers are not safely cross-comparable against the corpus — context is missing.

Reported
0
Omitted
0
Missing
18
Weighted score
0/55

Citing this tool in your research

Frons, S. (2026). MESSAI: An open-source platform for cross-study
comparison and reproducibility in microbial electrochemical systems.
EU-ISMET 2026. https://messai.io/tools/reproducibility