ELECTROCHEMISTRY LABS PAY THOUSANDS FOR A ROTATING DISC ELECTRODE. THIS ONE IS UNDER 100 DOLLARS
Electrochemistry labs pay thousands for a rotating disc electrode; this one is a 3D print, a DC motor and common hand tools.
by A Shnier, T Velempini and A Falch
ScienceOpen-hardware
Built withESP32Arduino3D printing
- difficulty
- ●●●●○
- time
- a long weekend
- license
- MIT (software), SHL-2.1 (hardware)
- repo
- repo FINISHED0 stars
●●●●○ · a long weekend · MIT (software), SHL-2.1 (hardware) · 0 stars · repo FINISHED
WHAT YOU’LL NEED
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COMPAREE VERDICT
A rotating disc electrode spins a small disc of electrode material at a precisely controlled speed inside solution; the controlled flow sets the mass transport so you can measure what the reaction itself is doing. Battery, fuel cell and catalyst work depend on it, and the paper puts commercial units above 5,000 dollars. This build uses a 3D printer, an electric drill and hand tools: a DC motor with a belt drive, an optical gap sensor and tachometer wheel for closed-loop speed control, a rotary encoder to set RPM, spring-loaded carbon brushes on a copper slip ring to carry the current, and a sprung test probe that contacts the removable electrode insert. Reported performance: at a 1600 rpm set-point the mean was 1600.41 rpm with a standard deviation of 0.91 rpm, ferri/ferrocyanide gives the expected Levich behaviour, and repeated oxygen-evolution scans on nickel in 1 M KOH overlap closely. The authors at Wits designed it explicitly for lower-budget research groups and teaching institutions. The one thing most likely to trip someone up: you still need a working potentiostat and the electrochemistry knowledge to set up a three-electrode cell and interpret the output. This is the missing rotator that makes the electrochemistry you already do cheaper, not a turnkey station.
IN THE REPO
GOOD TO KNOW
- —Full bill of materials and assembly manual in the HardwareX paper (DOI 10.1016/j.ohx.2025.e00626); FreeCAD and STL files on Mendeley Data; ESP32 code on GitHub.
- —Software is MIT, hardware is SHL-2.1 (Solderpad Hardware License 2.1); both permit commercial use.
- —Validation data published for a ferri/ferrocyanide Levich plot in 0.1 M KCl and oxygen evolution on a nickel electrode in 1 M KOH; this is a working prototype, not a certified instrument.
- —You still need a potentiostat — the RDE is the rotator, not the complete electrochemistry rig.
- —The paper names commercial analogues (Pine WaveVortex 10, Biologic BlueRev, ALS RRDE-3A, Ivium rotator) and says commercial RDEs start above 5,000 dollars, with some over 10,000 dollars; the build's BOM totals about 98 dollars.
- —Design files are on Mendeley Data (doi.org/10.17632/r4mh958pgm) and the firmware is on GitHub (github.com/AShnier/RDE).
Parts to buy
9 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 (The assembly manual, BOM and validation data are all in the supplementary files.)
- 2.Print the mechanical parts(STL and FreeCAD files are on Mendeley Data; start the print queue early as there are several parts.)
- 3.Order the electronics(The paper specifies the motor, sensor and encoder models; order all components from the BOM in one go to avoid waiting twice.)
- 4.Upload the Arduino firmware and test the speed loop(Test with no electrode attached first; the tachometer and display should stabilise at the set RPM within a few revolutions.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- You still need a potentiostat — this is the rotator only, not a complete electrochemistry rig. If you do not already have one, this build does not help.
- The design files (FreeCAD and STL) are on Mendeley Data and the code is on GitHub (AShnier/RDE); the assembly manual is in the paper's supplementary information, so you are pulling from three places.
- The optical gap sensor alignment is critical — if the tachometer wheel does not pass cleanly through the gap, the speed loop will hunt and the RPM will wander.
- Contact resistance through the brushes and slip ring drifts and affects measurement precision; polish the slip ring as described, keep the copper rotor dry, and measure the resistance as the authors did.
- The validation data is for ferri/ferrocyanide in 0.1 M KCl and oxygen evolution on nickel in 1 M KOH; in other electrolytes check chemical compatibility of the printed parts (the authors found PETG turns brittle in 1 M KOH within weeks) and revalidate yourself.
- The authors designed this for a South African university context where precision machining is not available; if you have access to a lathe and a mill, a machined shaft and bearing block will be more rigid than the printed version.
Do I need electrochemistry experience to build this?
You need enough to set up a three-electrode cell, run a cyclic voltammogram and interpret the output. The RDE makes that work cheaper and more repeatable, but it does not teach you electrochemistry.
What potentiostat do I need?
Any potentiostat that can run a three-electrode cell will work; the RDE is independent of the potentiostat brand. The authors validated with a lab instrument but do not specify the model.
How does the speed stability compare to a Pine Research rotator?
The paper does not publish a direct comparison with a commercial rotator. It reports a mean of 1600.41 rpm with a standard deviation of 0.91 rpm at a 1600 rpm set-point, an operating range of 300–2000 rpm, and linear Levich plots for ferri/ferrocyanide. For teaching or proof-of-concept work that is enough; for publication-quality kinetics you may still want a commercial unit.
Can I use this for a ring-disc electrode?
Not as published — the design is for a disc electrode only. Adding a ring would require a second brush contact and a more complex rotor design.
Where do I get the electrode disc?
The design takes removable electrode inserts contacted by a sprung test probe. The authors used a 5 mm platinum working electrode for the Levich tests and a bare nickel electrode for oxygen evolution; the insert and cap details are in the supplementary information.
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Discussion1
FROM THE COMPAREE TEAM
The paper reports a mean of 1600.41 rpm at a 1600 rpm set-point, with a standard deviation under 1 rpm, plus Levich and nickel oxygen-evolution tests. If you had to validate one more redox couple to trust this for your own work, which one would you pick?
A Shnier, T Velempini and A Falch
The authors are at the Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand in Johannesburg. They designed this explicitly for lower-budget research groups and teaching institutions where commercial RDEs are out of reach, writing plainly that the instrument budget is the binding constraint in the South African context.
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- 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.
CompareeTEAM28d agoedited
Practical notes from our verification: the design files are split across two places: STL and FreeCAD files plus the authors' operation videos are on Mendeley Data, the ESP32 firmware is on GitHub (AShnier/RDE), and the build manual is in the paper's supplementary information. The authors designed it to need only a 3D printer, an electric drill and hand tools, with no lathe or machine shop; they also say a stainless steel rotor would be a higher-quality option than the copper one, which is sensitive to corrosion. The validation is solid for a prototype: linear Levich plots and oxygen evolution scans on a nickel electrode. The single biggest thing to know before ordering parts: you still need a working potentiostat and the electrochemistry knowledge to interpret the output; this is the missing rotator, not a turnkey electrochemistry station. 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.