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YOU CAN BUILD A 260-DOLLAR WEARABLE SCANNER DESIGNED TO IMAGE BREATHING LUNGS WITH TINY CURRENTS

A belt of electrodes and a 260-dollar circuit designed to image breathing lungs with tiny currents — no X-rays, no radiation, up to 25 frames per second; so far tested on a saline phantom.

by Andrew Creegan, Joshua Bradfield, Samuel Richardson, Llewellyn Sims Johns, Kelly Burrowes, Haribalan Kumar, Poul M.F. Nielsen, Merryn H. Tawhai

FULL CAD BOM FIRMWARE DOCS

HealthOpen-hardware

Built withTeensy

difficulty
●●●●●
time
several weekends
license
GPL-3.0
repo
repo FINISHED0 stars

WHAT YOU’LL NEED

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COMPAREE VERDICT

Electrical impedance tomography sends a tiny current through a ring of electrodes around the chest and reconstructs, from the voltages that come back, a cross-section of how conductivity changes inside — and because air changes lung impedance strongly, it can show breathing. The Auckland Bioengineering Institute team built a low-cost wearable version around a Teensy 3.6 that drives up to 32 electrodes at 25 kHz with a frame processing rate up to 25 Hz. The paper's comparison table lists the Dräger PulmoVista 500 bedside unit at 25,000 to 39,000 dollars, against about 260 dollars for this build. The authors validated it on a saline phantom and say testing in human subjects is still future work; the design targets the IEC 60601 limit of 100 microamps (it outputs 98). The published files contain the Altium PCB design and BOM, firmware, and a desktop app with real-time pyEIT reconstruction under GPL v3, and the board can be ordered pre-assembled. There is no regulatory approval. This is a research instrument, not a weekend project: the hard part is understanding electrode contact, current injection patterns and reconstruction, and verifying safety yourself.

GOOD TO KNOW

  • —Design files (Altium PCB and schematics, BOM, firmware and the desktop app) are published at DOI 10.17632/xn4pj3rt7b.1 under GPL v3.
  • —Detailed academic paper (HardwareX, DOI 10.1016/j.ohx.2024.e00521, open access CC BY 4.0) includes performance validation against a phantom.
  • —Authors state it meets IEC 60601 medical electrical safety standard (100 µA patient current limit).
  • —This is research hardware, not a certified medical device—it cannot diagnose anyone.
  • —GPL v3 allows commercial use, but the medical safety claims require independent verification before any clinical application.
  • —Build instructions and a GUI app are included, written for researchers rather than beginners.

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Can I build this?

PrintOptional: the authors housed the module in a 3D-printed case, but no case or belt files are published, so you design your own.
BuyThe electronics module (order it pre-assembled using the provided CAM files and BOM), a Teensy 3.6, and your own electrodes and belt — the published BOM covers the PCB only.
ToolsA PCB assembly service (or SMD soldering setup), a precision current meter and oscilloscope for verification, and a computer for the Python/pyEIT desktop app
SkillsAdvanced electronics assembly, firmware (C/C++), signal processing, and a working understanding of bioimpedance measurement. If you have not built instrumentation amplifiers or dealt with patient safety standards, start somewhere simpler.
TimeSeveral weekends: PCB assembly and testing alone is a weekend, firmware setup another, electrode fabrication and belt integration a third, then validation and tuning.
Cost$$ — the paper puts the hardware at about 260 dollars; the board can be ordered pre-assembled from a PCB assembly service, whose fee depends on the service.
SafetyThis applies current to a human body. The authors state it meets IEC 60601 with a 100 µA limit, but you must verify that yourself—measure it, test it, do not assume. Do not connect this to mains power and a person simultaneously. Do not use it on anyone with an implanted device (pacemaker, defibrillator) without explicit medical guidance. This is research hardware, not a certified medical device.

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. 1.Read the paper (HardwareX article, open access. This is the documentation. Start here before ordering anything.)
  2. 2.Download design files (DOI 10.17632/xn4pj3rt7b.1 — Altium PCB project and PDF schematics, BOM spreadsheet, firmware and the desktop acquisition app.)
  3. 3.Understand EIT fundamentals(If you have not worked with bioimpedance measurement before, read the paper's introduction and the cited review articles. You need to know why electrode contact impedance and current injection patterns matter.)
  4. 4.Validate your current source(Before connecting to a person, measure the output current with a precision current meter across the full frequency and electrode configuration range. Verify the 100 µA limit holds.)

KNOWN ISSUES

  • This is not a beginner project. The difficulty is not the soldering—it is the signal processing, the electrode design, the reconstruction algorithms, and the safety verification. If you have never built a biomedical instrument, this is the wrong place to start.
  • The paper's build instructions are brief and aimed at engineers; there is no forum, and you will be reading datasheets, schematics and academic methods sections.
  • Electrode quality dominates image quality. The belt must make consistent, low-impedance contact with skin across all 16-32 electrodes while the subject breathes. That is harder than it sounds.
  • Reconstruction runs out of the box in the supplied pyEIT-based app, but changing the electrode count or excitation pattern means editing pyEIT protocol settings and understanding what they do.
  • Patient safety is your responsibility. The authors state IEC 60601 compliance, but they tested their specific build. If you change components, PCB layout, or firmware, you must re-verify current limits and leakage paths yourself.
  • This is research hardware, not a medical device. It cannot diagnose, it cannot replace clinical imaging, and it has no regulatory approval anywhere. Do not use it to make medical decisions.

What is the image resolution?

Much lower than CT or MRI. EIT shows regional changes in conductivity — in the lungs, where air goes — not anatomical detail. The paper reports resolution, position error and ringing from saline-phantom tests, and found it performed similarly to other published devices.

Can I use fewer electrodes?

Yes — the hardware supports 4 to 32 electrodes (the default protocol uses 16). Fewer electrodes mean lower resolution but simpler assembly and faster frames.

Do I need the exact components in the BOM?

The Teensy 3.6 (which generates the excitation and digitises the signal), the current source and the AD8220 amplifier stages are what matter; passives can usually be substituted, but changing the analogue front-end or microcontroller means firmware and calibration changes.

Is this safe to use on myself?

Not without proper oversight. The design targets the IEC 60601 limit of 100 microamps (it outputs 98), but the published validation is on a saline phantom only and the device has no regulatory approval. Any use on people belongs in a supervised research setting with independent safety testing, and never on someone with an implanted electronic device.

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Discussion1

FROM THE COMPAREE TEAM

The paper's comparison table lists the Dräger PulmoVista 500 at 25,000 to 39,000 dollars, and this build at about 260 — but so far it has only been validated on a saline phantom. What would your first test be?

CompareeTEAM26d agoedited

Practical notes from our verification: the design files are hosted on Mendeley Data (DOI 10.17632/xn4pj3rt7b.1), not GitHub — the Gerbers and bill of materials for the Teensy 3.6-based electronics module, precompiled firmware, and the open-source desktop app, which uses the pyEIT library for real-time reconstruction — under GPL v3. The paper itself (HardwareX, 2024) is the real documentation: it covers the build and operating steps, measurement uncertainty, phantom tests against EIT-specific performance measures, and safety, with the device designed around the IEC 60601 limit of 100 microamps across the subject (it outputs 98). You do not have to solder the board yourself: the authors note the electronics module can be ordered pre-assembled from a PCB assembly service. There is no project website or demo video. The paper prices the hardware at about 260 dollars and lists the Dräger PulmoVista 500 at 25,000 to 39,000 dollars in its comparison table. The hardest part is not building it — it is understanding whether what you built measures correctly and stays within the safe current. 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.

Andrew Creegan, Joshua Bradfield, Samuel Richardson, Llewellyn Sims Johns, Kelly Burrowes, Haribalan Kumar, Poul M.F. Nielsen, Merryn H. Tawhai

The team works at the Auckland Bioengineering Institute, University of Auckland, on lung physiology. They needed a low-cost, portable EIT device for monitoring free-breathing subjects, found no suitable complete open-source one, and published theirs in HardwareX so other groups can build on it.

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