YOU CAN BUILD AN AUTONOMOUS RIVER DNA SAMPLER FOR ABOUT 3,800 DOLLARS IN PARTS
An autonomous sampler that collects over twenty filtered eDNA samples across a month, no operator standing in the river, for roughly a fifteenth of what the commercial equivalent costs.
by Riley Prince, Kai Roy, Nathan Jesudason, Marc Belinga, Jacob Field, Dylan Heiesy, Aaron Arvidson, Torrey Menne, John Selker and Chet Udell
ScienceOpen-hardware
- difficulty
- ●●●●●
- time
- weeks, plural
- license
- CERN-OHL-S-2.0 (hardware), AGPL-3.0 (firmware)
- repo
- repo FINISHED0 stars
●●●●● · weeks, plural · CERN-OHL-S-2.0 (hardware), AGPL-3.0 (firmware) · 0 stars · repo FINISHED
WHAT YOU’LL NEED
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COMPAREE VERDICT
PolyWAG is an autonomous environmental DNA sampler that holds 24 filters and collects filtered water samples over roughly a month without an operator on site. The paper puts the component cost at about 3,800 dollars (6,000 with labour), against about 55,000 dollars for the closest commercial multi-sample autonomous unit, which is also submersible; PolyWAG is not. The hard part it tackles is cross-contamination: each sample runs a 13-step sequence of flushing, filtering, preserving and purging that the authors say significantly reduces carryover. The build is genuinely documented: 182 figures, a BOM, PCB and CAD files and firmware on Zenodo. It assumes you can do stencil-and-paste SMD assembly, modify Advantec filter housings with quick-disconnects and check valves, and debug a peristaltic pump, ball valve and 27 solenoid valves driven by a custom board with an Adafruit Feather M0. Difficulty is a hard 5: a blocked filter or stuck valve can waste a field deployment, and the complete unit with case and a month of ethanol preservative weighs about 43 kg. If you are an ecologist tired of standing in a stream every few days and have the bench skills, this is a serious, well-documented tool.
IN THE REPO
GOOD TO KNOW
- —Published as a complete HardwareX article with 182 figures, BOM, CAD and PCB files, firmware and step-by-step assembly instructions.
- —Files are on Zenodo (doi 10.5281/zenodo.14160133): hardware under CERN-OHL-S v2, firmware under AGPL-3.0.
- —CERN-OHL-S v2 is strongly reciprocal, which means derivative works must be released under the same licence and you must document changes. Commercial use is permitted but must preserve these terms.
- —The paper states cost is around 3,800 dollars in components, 6,000 dollars with labour. Those are 2024 numbers and do not include tools or shipping.
- —Not submersible — the paper explicitly states it is not rated for underwater deployment.
- —The filtering is mechanical; the DNA analysis happens later in a lab. This is a sample collection system, not a sequencer.
Parts to buy
10 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the HardwareX paper front to back (182 figures, BOM and assembly sequence: read it all before ordering anything.)
- 2.Download the files from Zenodo(doi 10.5281/zenodo.14160133 — PCB Gerbers, firmware, CAD. Verify the licence terms before you start.)
- 3.Order the custom PCB from a board house(The PCB files are provided; the board is assembled with a solder stencil and paste. Inspect it before buying the rest of the parts.)
- 4.Source the pump, valves, sensors and housings from the BOM(The filter housings are Advantec filters you modify with a CPC quick-disconnect and a one-way check valve; the paper warns against cracking them or over-tightening the check valve thread.)
KNOWN ISSUES
- Getting the custom board right. It is SMD work with a stencil and solder paste, so an error in fabrication or assembly means another board run.
- Skipping a test deployment near home. The first time you deploy this in the field, something will leak, stick, or time out. Test it in a bucket in your workshop for a full 24-hour cycle before you drive three hours to a river.
- Assuming the purge sequence works identically in all conditions. Flow rate, pressure, temperature and particulate load all affect how well the lines clear. The paper gives one set of parameters; your site may need different ones.
- Order the long-lead and specialised parts (pump, valves, Advantec filters, sensors) early and check the BOM against current availability before you start.
- Ignoring the preservative's safety data sheet. The sampler pumps a DNA preservative (the authors' unit carries a month of ethanol) over every filter, so read the SDS for whatever preservative you choose: gloves and ventilation are not optional, and ethanol in bulk is flammable.
- Treating this as a weekend project because it is open source. It is not. The paper is thorough, but you are building a fluid handling system with 13 steps per sample, a custom PCB, and field deployment variables. Budget weeks, not days.
Does this identify species on its own?
No. PolyWAG collects and preserves filtered water samples. The DNA analysis happens later in a lab with sequencing equipment. This is the hard part of sample collection, not the sequencing.
Can I deploy this underwater?
No. The paper explicitly states it is not submersible. It is designed to sit at the water's edge or on a platform, with an inlet tube in the water.
How much does the PCB run actually cost?
The paper does not break out the PCB cost; it gives about 3,800 dollars for all components (6,000 with labour). Get a quote from a board house using the published files.
What is the CERN-OHL-S v2 licence?
Strongly reciprocal open hardware licence. You can build, modify and sell this, but any changes must be released under the same licence and documented. It is the hardware equivalent of copyleft.
Why is difficulty a 5?
Custom PCB with surface-mount soldering, mechanical fabrication of pressure-rated housings, multi-step fluid handling logic, and field deployment debugging. If any one of those is new to you, start with a simpler project.
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Discussion1
FROM THE COMPAREE TEAM
The paper puts the commercial autonomous alternative at about 55,000 dollars and this one at about 3,800 dollars in components (6,000 with labour) — but the real question is the month of field deployment. What would stop you trusting it unattended for that long?
Riley Prince, Kai Roy, Nathan Jesudason, Marc Belinga, Jacob Field, Dylan Heiesy, Aaron Arvidson, Torrey Menne, John Selker and Chet Udell
Designed at the OPEnS Lab, Oregon State University. Published as a complete HardwareX article in 2024 to make autonomous eDNA sampling accessible to researchers without 55,000 dollars budgets. The lab focuses on open-source environmental sensing.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM18d agoedited
Practical notes from our verification: this is published as a HardwareX article, not a GitHub repo, so the files and the BOM live on Zenodo and the paper itself is the build guide. The 182 figures are genuinely step-by-step, but they assume you have built a fluid handling system before or are prepared to learn by debugging one. The filter housings are commercial Advantec housings that you modify by cutting, drilling and tapping them and adding a quick-disconnect and check valve — the paper warns about cracking the filter and over-tightening the check valve thread, so take that step slowly. The paper does not include a video, so your reference is the figures. Water is moved by a peristaltic pump rated at about 400 mL per minute, the electronics board drives 27 solenoid valves and is conformal coated before deployment, and the complete unit with case and a month of ethanol preservative weighs about 43 kg. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.