3DPLAM

• Moreno Gabriel — ETH Zürich, Global Health Engineering — design, construction, testing, writing
• Jakub Tkaczuk — 0000-0001-7997-9423 — ETH Zürich, Global Health Engineering — supervision, page development & maintenance
• Caetano Dorea — 0000-0001-9367-0668 — University of Victoria — supervision
• Elizabeth Tilley — 0000-0002-2095-9724 — ETH Zürich, Global Health Engineering — supervision

Open-source, 3D-printable membrane-filtration manifold for Escherichia coli quantification in drinking water. Three printed parts — base, funnel, filter support — plus a syringe and a membrane filter, all printable without support structures on any FDM printer. Validated against a Millipore EZ-Fit™ stainless-steel manifold as the reference instrument for the household drinking-water testing used in WHO/UNICEF water-quality surveys. 3DPLAM is not a replacement for that instrument — its contribution is that the design is open and can be printed locally, where the reference instrument can only be bought.

Full site, with photos, renders and the print-settings requirement available here.

At a glance

Parts	Base + funnel + filter support (2 concurrent alternatives), no supports
Material cost	≈ $0.80 per set (ABS)
Mass	≈ 32 g
Print time	≈ 100 min
Reference instrument	Millipore EZ-Fit™ stainless-steel manifold (≈ $2,460)
Validation	8 sites × 3 manifolds × 3 replicates = 72 filtrations, 16 printed-vs-reference comparisons
Headline result	15 of 16 classifications accepted within the 5% WHO boundary-tolerance rule; 12 of 16 match exactly with no tolerance applied
Sustainable route	Funnel and filter support printable in rPET from recycled bottles

Quick start

1. Read hardware/README.md for the parts table, envelopes, and the choice between the two filter-support and two funnel variants.
2. A manifold sliced at default settings is porous: the syringe draws air through the walls instead of pulling water through the membrane, and filtration fails. Import the profile for your printer from hardware/print-profiles/ and read hardware/print-profiles/README.md for the any-slicer equivalents.
3. Print stl/base.stl, stl/funnel.stl and stl/filter-support-strand-mesh.stl (the default, validated filter support) as separate jobs.
4. Assemble and operate the manifold following docs/assembly.md and docs/operation.md.

When printing in recycled PET instead of ABS, use the geometry in hardware/rpet/, not hardware/stl/ and see docs/rpet.md.

Repository layout

hardware/           CERN-OHL-S v2 — the parts to print
├── README.md       Parts table, envelopes, variant choices
├── stl/            Printable meshes (millimetres)
├── step/           Editable B-rep — modify the design here
├── rpet/           Shrinkage-compensated geometry for recycled PET
├── assembly/       Reference assembly (not a printable part)
├── print-profiles/ Slicer settings for a gas-tight print
└── onshape.md       Source CAD, by version

docs/               CC BY 4.0 — how to print, build, run and interpret it
├── printing.md      Print settings, orientation, materials matrix
├── assembly.md       Putting the three parts together
├── operation.md      The E. coli filtration protocol, verbatim
├── validation.md      What was tested and the headline result
├── rpet.md            Bottle-to-filament, with upstream credit
├── design-history.md  Version history predating this repository
└── thesis.pdf         The BSc thesis this release is drawn from

data/               CC BY 4.0 — the tidied functional and material test data
tools/              Scripts that regenerate every figure and gate CI
site/               This repository's GitHub Pages site (Astro)
CITATION.cff        Machine-readable citation metadata

Citation

If you use this hardware, please cite it — see CITATION.cff for the machine-readable record:

3DPLAM — 3D-Printed Lightweight Affordable Manifold for Microbial Water Quality Testing. Moreno Gabriel, Jakub Tkaczuk, Caetano Dorea, Elizabeth Tilley. ETH Zürich, Global Health Engineering. https://github.com/Global-Health-Engineering/3dplam

Licence

Different parts of this repository are released under different licences, following standard practice for open-hardware projects:

Component	Licence
Hardware design (CAD, STL, STEP in hardware/)	CERN-OHL-S v2
Documentation (docs/, this README)	CC BY 4.0
Datasets (data/)	CC BY 4.0
Site and tooling (site/, tools/)	CC BY 4.0

The rPET route in hardware/rpet/ and docs/rpet.md rebuilds Petamentor2, an open-source PET-bottle-to-filament machine designed by Ondřej Šraitr (https://petamentor2.com/) — credited, not redistributed; build your own from the upstream project.