YOU CAN BUILD THE 20,000-DOLLAR MACHINE THAT STRETCHES LIVING CELLS, FOR 580 DOLLARS
A published open-hardware biaxial stretcher that sits on a microscope stage and costs 580 dollars instead of 20,000 dollars.
by Daniel J. Shiwarski, Joshua W. Tashman, Amity F. Eaton, Gerard Apodaca and Adam W. Feinberg
ScienceOpen-hardware
Built with3D printing
- difficulty
- ●●●●○
- time
- a weekend-plus
- license
- CC-BY-4.0
- repo
- repo FINISHED0 stars
●●●●○ · a weekend-plus · CC-BY-4.0 · 0 stars · repo FINISHED
WHAT YOU’LL NEED
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COMPAREE VERDICT
This is a peer-reviewed open-hardware biaxial stretcher designed to study how mechanical forces change cell and tissue behaviour. The key constraint was height: it had to fit on a microscope stage so samples could be imaged under fluorescence during stretching, not fixed and stained afterwards. The design is a 3D printed and laser-cut assembly with linear rods, GT2 belts and steppers pulling the sample in two axes. The controller is a Duet WiFi 3D printer board with a PanelDue touchscreen, so stretch programmes are just G-code macros. The paper states commercial biaxial stretchers cost 20,000 dollars to 100,000 dollars; theirs costs 580 dollars. Files are complete and the strain field was validated optically. The difficulty is not the build itself - it is 3D printer motion hardware - but the context: you need access to a fluorescence microscope and tissue or cell culture facilities to use this for its intended purpose. If you have those, this is a published, validated, replicable design. If you do not, you are building motion hardware with no clear application.
IN THE REPO
GOOD TO KNOW
- —STL and STEP CAD files for every printed part (plus the acrylic base plate) are on Zenodo (10.5281/zenodo.3483849); the bill of materials and step-by-step assembly instructions are in the HardwareX article, and the article says G-code macros and a MATLAB script for generating them are provided as downloadable files.
- —Licence is CC BY 4.0, which permits commercial use with attribution.
- —Controller is a Duet WiFi 3D printer board with a PanelDue 5i touchscreen; stretch programmes are G-code macros.
- —The paper includes optical strain field validation and live bladder cell imaging data, not just the hardware description.
- —No custom firmware to compile: the Duet WiFi ships with its firmware pre-loaded and the stretcher is driven by G-code; the unique part is the physical design.
- —Published in HardwareX (DOI 10.1016/j.ohx.2020.e00095), peer-reviewed for replicability.
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 published HardwareX article (DOI 10.1016/j.ohx.2020.e00095) in full - it contains the design rationale, assembly instructions and validation data (Open access, no paywall)
- 2.Download the CAD files (STL and STEP) from Zenodo; take the bill of materials and assembly steps from the article (All design files are CC BY 4.0)
- 3.Source the components from the BOM - steppers, linear hardware, Duet WiFi board and PanelDue 5i display(Most non-printed parts are standard 3D printer motion components)
- 4.Print the frame and mechanical parts, assemble per the article instructions, and connect the Duet WiFi (it ships with firmware pre-loaded)(G-code macros for stretch patterns are provided, you run them from the PanelDue touchscreen)
KNOWN ISSUES
- This is a research instrument - you need access to a fluorescence microscope and cell culture facilities to use it for its intended purpose, it is not a standalone project
- Sample mounting is where the work is. The paper uses 3D printed rakes that pierce the sample, clamping grips, or adhesive grips, and provides jigs for bending and mounting the rakes; getting a delicate sample attached evenly without tearing takes practice.
- Microscope stage compatibility - the height constraint was designed around specific microscopes, you may need to modify the frame or stage adapter for yours
- Check the strain yourself. The paper validated the device by tracking fiducial marks about 5 mm apart on a PDMS film during stretching; do the same with your build before you trust the stretch values.
- G-code macros are model-specific - the provided examples are for their validation experiments, you will have to write your own for different stretch protocols
- No ongoing support or community - this is a published design from 2020, not an actively maintained project, so troubleshooting is on you
Can I use this without access to a microscope?
Yes. The main design goal was a low-profile stretcher that fits on a microscope stage for live fluorescence imaging, but the authors note it also works with stereo microscopes or an overhead camera, tracking fiducial marks to measure how a material deforms. That is how they validated it on PDMS film. The heated plate can also take non-biological samples up to 150 degrees C.
What did they test it with?
PDMS film for mechanical validation, and live rat bladder tissue in which umbrella cells were labelled with GFP-Claudin-8 and imaged by confocal microscopy while the tissue was stretched; the paper reports changes in cell perimeter and area.
Do I need to flash firmware?
No. The Duet WiFi comes pre-loaded with firmware and works out of the box; you only configure it and run the supplied G-code macros (or generate your own with the MATLAB script provided).
How long does a typical stretch experiment take?
That depends on the protocol. The paper shows stepwise stretching with imaging between intervals and cyclic stretching up to about 5 Hz; the limiting factor is usually how long your sample stays viable and in focus.
What is the maximum strain it can apply?
The authors report uniaxial and biaxial strains of more than 200%, depending on sample shape, size and elasticity. In practice the limit is your sample, not the machine.
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Discussion1
FROM THE COMPAREE TEAM
The paper validated the stretcher on PDMS film and on live rat bladder tissue imaged mid-stretch. If you built one, what sample would you put on it first, and how would you hold it?
Daniel J. Shiwarski, Joshua W. Tashman, Amity F. Eaton, Gerard Apodaca and Adam W. Feinberg
Daniel Shiwarski and Adam Feinberg are at Carnegie Mellon University's Department of Biomedical Engineering, Gerard Apodaca at the University of Pittsburgh School of Medicine. They published this in HardwareX in 2020 as part of research into how mechanical forces regulate cell behaviour, with a focus on bladder tissue mechanobiology. The design was driven by a need to image live cells during stretch without the cost barrier of commercial systems.
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DISCLAIMER
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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.
CompareeTEAM17d agoedited
Practical notes from our verification: this is a peer-reviewed, open-access HardwareX publication from 2020, not a GitHub project; the design files are on Zenodo (doi.org/10.5281/zenodo.3483849). The motion side is built like a small 3D printer and is controlled by a Duet WiFi board with a PanelDue touchscreen running its own pre-loaded firmware. The paper validates the device on PDMS film and on intact rat bladder tissue, reporting strains above 200 percent depending on the sample and cyclic stretching up to about 5 Hz. The practical barrier is less the build than the context: to use it as intended you need imaging and tissue or cell culture facilities. In a lab that already stretches samples, it is a low-cost published alternative to commercial systems; outside one, it is mainly an interesting motion-control build. 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.