YOU CAN BUILD A LAB MACHINE THAT MOVES DROPLETS AROUND LIKE A VIDEO GAME
A desktop machine that walks droplets around a grid with voltage alone — no pumps, no tubes, just electrodes and physics.
ScienceOpen-hardware
Built withArduino3D printing
- difficulty
- ●●●●○
- time
- a weekend-plus
- license
- GPL-3.0
- repo
- repo ACTIVE486 stars
●●●●○ · a weekend-plus · GPL-3.0 · 486 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
OpenDrop is a serious lab instrument project for people who already solder electronics and want to explore digital microfluidics — the technique that moves tiny droplets around a flat grid using voltage instead of pumps. The physics is elegant: electrodes under a hydrophobic surface pull drops from square to square, so you can program liquid handling like a chess game. The repository includes the KiCad electronics for several hardware versions, the cartridge designs, Arduino firmware and a Processing desktop controller. The hard part is not the electronics — it is the droplet handling itself. Getting reliable movement depends on surface prep, reagent properties, and voltage tuning, and the docs do not walk you through that troubleshooting. The single biggest trap is expecting plug-and-play: you will need to experiment with coatings, droplet volumes and settings before drops reliably obey. If you have lab access or a strong background in chemistry or biotech, this is a rare open-hardware path into a technology that is otherwise locked behind expensive commercial platforms; GaudiLabs also sells assembled units if you would rather start from a working device.
IN THE REPO
GOOD TO KNOW
- —Full PCB design files, firmware, and mechanical CAD present in the repository under GPL-3.0.
- —The V4 materials spreadsheet lists parts with order numbers and suppliers; a few specialised items (HV507 drivers, ITO glass, hydrophobic coating) come from specialist sources.
- —Assembly instructions exist but assume intermediate electronics skills — there is no beginner walkthrough.
- —The cartridge design is included; fabricating the hydrophobic surface requires lab access or experimentation.
- —GaudiLabs sells assembled units; the open hardware release is for people who want to build or modify.
- —GPL-3.0 licence permits commercial use with source release.
Parts to buy
10 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
- Main board and driver board PCBs (Gerbers provided)from the repo files
- Two HV507 high-voltage driver chipsFind
- Mini-DIMM connectorFind
- Small OLEDFind
- Joystick and switchFind
- Cartridge PCBsFind
- ITO-coated glassFind
- Hydrophobic coating (the materials list uses Fluoropel)Find
- Sylgard 184 siliconeFind
- Conductive tapeFind
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 repository README and the project pages at gaudi.ch/OpenDrop to understand the full scope before buying parts (The BOM and build instructions are there; start by confirming you can source the high-voltage ICs and coating material)
- 2.Order the PCBs — design files and Gerbers are in OpenDropV4/Electronics(Each V4 board (main board, driver board, cartridge, frame, adapters) has its own Gerber zip; check the layer count and thickness in each before ordering.)
- 3.Source components per the BOM; pay attention to the high-voltage driver and hydrophobic coating(Some parts are specialised (HV507 drivers, ITO glass, coating); order them first)
- 4.Assemble the main board and driver board and flash the OpenDrop V4 firmware from the Arduino IDE before building the cartridge(Firmware is an Arduino sketch with its own OpenDrop library; the desktop controller is a Processing app. Test the electrical side first so you do not mix electrical and chemical troubleshooting later.)
KNOWN ISSUES
- The hydrophobic coating is the hardest part to get right: the V4 materials list uses a Fluoropel coating, and the project site has a dedicated page on the hydrophobic surface - read it before you coat your first cartridge, and work in a ventilated space.
- Droplet movement is sensitive to surface cleanliness, reagent viscosity, and voltage tuning. The docs explain the principle but not the iterative debugging — expect trial and error.
- The high-voltage driver ICs may not be in stock at common distributors; check lead times before committing to a build timeline.
- The repository does not include a beginner-friendly assembly video or step-by-step photo guide — you are working from schematics and text instructions.
- If you have never worked with lab reagents or surface chemistry, the cartridge fabrication will be steeper than the electronics.
- GaudiLabs sells assembled units; if you are building purely to save money rather than to modify or learn, compare the cost of parts plus your time.
What can I actually do with this once it is built?
Move, mix, and split microliter-scale droplets for experiments in chemistry, biology, or materials science. Common uses include mixing reagents, running enzymatic assays, or exploring new protocols without pipettes. It is a research tool, not a consumer product.
Do I need a biology or chemistry background to use it?
Not strictly, but you will get more out of it if you do. The machine handles droplets; what you do with them depends on your experimental goals. Without a lab context, it is a fascinating physics demo but not a daily-use device.
Can I buy a pre-assembled unit instead of building?
Yes — GaudiLabs sells assembled OpenDrop units. The open hardware release is for people who want to modify the design, save cost, or integrate it into other systems.
How does this compare to commercial digital microfluidics platforms?
Commercial digital microfluidics platforms come with support, certified protocols and regulatory compliance. OpenDrop trades those for open access and customisability, and it is aimed at researchers, educators and DIY bio labs, not regulated diagnostics. The project does not publish a total build cost, so price the materials list yourself.
What is the hardest part of the build?
Getting reliable droplet motion. The electronics usually work on the first try if you follow the BOM and schematics. The surface coating, droplet composition, and voltage settings require iteration and are not fully documented for every reagent type.
Community builds
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Discussion1
FROM THE COMPAREE TEAM
The hardest part is not the electronics — it is tuning the surface and reagents until drops reliably move. What would you experiment with first: reagent chemistry, coating technique, or voltage profiles?
Urs Gaudenz / GaudiLabs
Urs Gaudenz runs GaudiLabs, a Swiss open hardware lab focused on accessible scientific instruments for the DIY biology and maker communities. OpenDrop grew out of the hackteria network and the DIYbio movement and has gone through four hardware versions since 2014; GaudiLabs also makes the open PocketPCR thermocycler.
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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.
CompareeTEAM1mo agoedited
Practical notes from our verification: the repository is under the GaudiLabs organisation and the hardware files are there — KiCad designs and Gerbers for the board and the cartridges, BOM spreadsheets, the Arduino firmware and the Processing controller app — but there is no /docs folder and the README is short; it points to gaudi.ch/OpenDrop for the project write-up, including a page on the hydrophobic surface. The single biggest unknown before you start is the cartridge side: droplets only move reliably on a good hydrophobic surface, and that is surface chemistry rather than electronics. GaudiLabs also sells OpenDrop hardware in its shop if you would rather start from a working cartridge. If you have built electronics kits before but never worked with surface chemistry, budget extra time for the cartridge side. 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.