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YOU CAN BUILD THREE LAB SYRINGE PUMPS PLUS A MICROSCOPE FROM CALTECH'S OPEN DESIGN FOR UNDER 400 DOLLARS

Three syringe pumps and a microscope, 3D printed and assembled in under an hour for under 400 dollars, and in the published test they made droplets as consistent as a commercial Harvard Apparatus pump array.

by Pachter Lab, Caltech

FULL CAD BOM FIRMWARE DOCS

ScienceOpen-hardware

Built withArduinoRaspberry Pi3D printing

difficulty
●●●○○
time
an evening
license
BSD-2-Clause
repo
repo ACTIVE253 stars

WHAT YOU’LL NEED

Videos
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COMPAREE VERDICT

Poseidon is a three-pump syringe system plus a USB microscope station, designed for microfluidics research in Lior Pachter's lab at Caltech. Each pump is a 3D-printed body with a NEMA 17 stepper turning a threaded rod that pushes a sled on steel rods and linear bearings; an Arduino with a CNC shield drives up to three pumps, and a Python GUI runs them from a laptop or a Raspberry Pi with a touchscreen. The repo has the CAD (STL, STEP, IGES, Fusion 360), Arduino firmware, GUI source and a priced bill of materials from January 2019, and the design is described in a peer-reviewed Scientific Reports paper. The cost claim comes from the authors: under 400 dollars for the whole system, assembled in under an hour, and in their benchmark it made droplets with variance comparable to a commercial Harvard Apparatus array. The catch is that this is lab equipment, not a weekend curiosity. You will need to flash the Arduino, set the microstepping jumpers, pick the right syringe in the GUI (presets cover BD syringes from 1 to 60 mL), and understand what flow rates your experiment needs. If you are equipping a biology or chemistry lab on a budget, or replicating published microfluidics protocols, this is a well-documented open option. If you are just exploring what a syringe pump does, the learning curve is steeper than the mechanical build.

GOOD TO KNOW

  • —STL and STEP models present, Fusion 360 source files included
  • —Bill of materials with prices in the repo
  • —Arduino firmware and Python GUI both provided
  • —Build instructions in README, peer-reviewed paper in Scientific Reports (2019)
  • —BSD-2-Clause licence — permits commercial use
  • —Pre-built GUI executables for Windows, macOS and Raspberry Pi are on the Releases page; the Python source is there too if you want to modify it.

Parts to buy

8 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Per pump: a NEMA 17 stepperFind
  • Shaft couplingFind
  • 6 mm steel rods with linear bearingsFind
  • M5 threaded rod and nutFind
  • M3 screws and a knob to hold the syringeFind
  • Microscope station: Raspberry Pi 3Find
  • 7-inch touchscreenFind
  • USB microscopeFind

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Can I build this?

PrintPer pump: base, carriage sled, cover slide and syringe brace. For the microscope station: base, top stage and screen leg mount. Any desktop FFF printer works.
BuyPer pump: a NEMA 17 stepper, shaft coupling, 6 mm steel rods with linear bearings, an M5 threaded rod and nut, M3 screws and a knob to hold the syringe. Shared: an Arduino with CNC shield and a 12 V power supply. Microscope station: Raspberry Pi 3, 7-inch touchscreen, USB microscope. Syringes are bought separately. The BOM has prices and Amazon links from January 2019.
Tools3D printer, hex keys and basic hand tools, wire strippers for the power lead, a small screwdriver for the stepper driver current limit; Python 3 only if you run the GUI from source
SkillsIntermediate — mechanical assembly, basic Arduino, Python CLI comfort, ability to calibrate stepper motors
TimeThe authors assemble the whole system in about an hour once parts and prints are ready; plan an extra evening for flashing the Arduino, setting jumpers and learning the GUI.
Cost$$ — under 400 dollars for three pumps plus microscope. In the January 2019 BOM the three pumps come to about 175 dollars and the microscope station to about 180 dollars, with the Raspberry Pi's 7-inch touchscreen and the Raspberry Pi itself the biggest single items.
SafetyLow-voltage DC only (12 V for the motors), no mains work. But the pumps can build real pressure: the authors set the stepper driver's current limit so a motor stalls at about 4 MPa in a 1 mL syringe, before the printed PLA parts fail. Set your current limit the same way, and secure tubing before running. The README also recommends changing the Raspberry Pi's default password.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Poseidon Build Videos: Syringe Pump

Official build video from the Pachter Lab

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Gallery

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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. 1.Read the Scientific Reports paper(The paper explains the design rationale and precision validation — read it before you order parts)
  2. 2.Check the bill of materials(Priced BOM is in the repo — verify current component availability and cost)
  3. 3.Print the frame parts(STL files are in the repo — print one pump's worth first to confirm fitment)
  4. 4.Flash the Arduino firmware(Firmware is in the repo — upload it before mechanical assembly)
  5. 5.Download the GUI executable from the Releases page (or run the Python source)(Single-click executables exist for Windows, macOS and Raspberry Pi; Python 3 is only needed if you modify the GUI)

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

  • The pre-built GUI executables are from 2018–2019 (Windows, macOS, Raspbian). If they do not run on your current OS, you will need to set up Python with PyQt5 and run the GUI from source.
  • The BOM prices are from 2019. Stepper motors and linear rails have fluctuated — verify current costs before committing.
  • Volumes are converted to steps from the syringe preset and the microstepping setting, so both must match reality: put the three microstepping jumpers on the CNC shield as the README describes and set the same value in the GUI, or every volume will be off. Non-BD syringes need their area added in the code.
  • The design assumes you know what volumetric precision you need. If you are unsure, you will be learning that as you build.
  • No enclosure or case is provided — the pumps are open frames. If you need splash protection or a clean environment, you will design that yourself.
  • The microscope is a bonus inclusion, not the primary focus. Documentation for it is lighter than for the pumps.

Is this as precise as a commercial syringe pump?

For the job it was tested on, yes. The authors ran a droplet-generation microfluidics chip with poseidon and with a commercial Harvard Apparatus pump array and got comparable variance in droplet diameter. The paper also notes that open source instruments may not always perform as well as commercial ones, so benchmark it for your own protocol.

Can I use this for clinical or pharmaceutical work?

No. This is research-grade lab equipment. It is not certified for clinical, diagnostic, or pharmaceutical applications.

Do I need all three pumps?

No. The design is modular — you can build one, two, or three depending on your application. The GUI supports all three, but you can run fewer.

What syringes does it take?

The GUI has presets for BD syringes of 1, 3, 5, 10, 20, 30 and 60 mL and converts the volume you enter into motor steps using each syringe's cross-section. Syringes are not in the BOM, so buy them separately; another brand will need its area added in the code.

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Discussion1

FROM THE COMPAREE TEAM

The authors put the whole system, pumps plus microscope, at under 400 dollars and about an hour of assembly. If you were equipping a lab from scratch, what would you pair this with first?

CompareeTEAM1mo agoedited

Practical notes from our verification: the repository is stable and complete — STL, STEP, IGES and Fusion 360 files, the Arduino firmware, the Python GUI source, a bill of materials and build videos for the pump, the microscope, the Arduino and the Raspberry Pi are all there. The bill of materials is dated January 2019, so check current component prices before ordering. You do not need to compile the GUI: the project publishes single-click executables, and running from source is optional. Set the microstepping jumpers on the CNC shield as the README describes, or the step counts will be wrong. The single biggest hurdle is not the mechanical build — it is understanding what precision you need and how to calibrate for it. If you know why you need a syringe pump, this is the standard open alternative. If you are exploring, expect the learning curve to be steeper than the assembly. 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.

Pachter Lab, Caltech

Poseidon was built in Lior Pachter's lab at Caltech by A. Sina Booeshaghi, Eduardo da Veiga Beltrame, Dylan Bannon, Jase Gehring and Lior Pachter, because the lab's commercial, tightly integrated pump system was too rigid for their changing microfluidics experiments. They published the design and the principles behind it in Scientific Reports in 2019.

GitHub

Star the project on GitHub

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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.
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