Open Source Biomedical Imaging

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Imagine a world where biomedical imaging technology is so accessible that it’s easy to use and build on. Medical physics is a fascinating way to explore signal processing and electricity. Come and discover an open source biomedical imaging system based on electrical impedance tomography.


Biomedical imaging is an amazing area of physics and electronics, but rarely has it been in the category of ‘hackable’ since MRI and CAT scan machines are so expensive and large. If there was a cheaper, smaller system that could fit on your desk and was safe to use with the same ideas and operating principles, would you think it worthwhile to improve and explore? Since imaging is one of the major costs in healthcare, if we can develop a system that’s cheap and easy to reproduce we could all have better health.

Spectra is designed to be used with a small tank (called a “phantom” in biomedical imaging circles) to image anything inside the tank. This Electrical Impedance Tomography (EIT) system is only 2” square but is feature-packed and professional-grade.

Spectra with fruit

Whether you are an interested hacker or a professional academic exploring bio-impedance spectroscopy and tomography applications, this system comes ready to go; you can get started just by double-clicking to run the application to start doing image reconstructions.

Lung cross-section at a single 50 kHz frequency

Example Applications


Run multifrequency EIT to get a spectrum at every pixel and use this information to identify objects. Identify where the seed is inside the peach, the watermelon rind vs the inside, use a piece of chicken to differentiate fat, muscle, bone, and more. Discover new things you want to identify within a black box conductive medium. E.g., try tumors, fruit seeds, areas of higher and lower blood flow (BOLD signal), etc.

Material identification in space

Time Series Mesaurement

With time series measurement you can measure the expansion and contraction of your lungs:

Time series changes

Using Spectra and time series measurement, you can also:

  • Measure blood flow changes in your heart - perform impedance cardiography.
  • Image smaller things to determine the presence of different types of cells, e.g., hemoglobin in a blood sample.
  • Develop better algorithms to obtain a higher resolution spatial reconstruction. The current algorithms make some limiting physics assumptions and need your help!

This shows how the position of a cup can be reconstructed with only electrical signals

Easy-to-use Software

This is the reconstruction software. Easy to get up and running doing image reconstructions.


  • 32 electrodes
  • Bluetooth
  • Accelerometer
  • 160 kSPS sample rate for impedance measures
  • 16-bit resolution bio-impedance spectroscopy with differential referencing
  • PCB is a tiny and portable 2” square
  • Open source software comes with three different types of tomographic reconstructions: GREIT, Gauss-Newton Method, and Back Projection
  • You can do time series impedance measurements, bio-impedance spectroscopy, as well as electrical impedance tomography between 80-80 kHz with up to 32 electrodes
  • DC removal filters to meet IEC60601-1 safety specifications
  • Comes with cylindrical tank and flexible electrode cable for testing

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