Spectra: A Portable, Open Source Biomedical Imager That’s Only Two Inches Square

Biomedical imaging systems such as CAT and MRI machines provide medical professionals with a wealth of information when it comes to…

Cabe Atwell
7 months ago

Biomedical imaging systems such as CAT and MRI machines provide medical professionals with a wealth of information when it comes to diagnosing ailments. Both machines are large and incredibly expensive, which makes them unavailable for candidates in the portable medical device sector, or even the hacker and maker communities for that matter.

Neuroscientist and avid hacker Jean Rintoul, the creative mind behind the medical devices Kiddo and Brightly (along with a host of others), has done the impossible by designing Spectra — a small, portable EIT (Electrical Impedance Tomography) medical imager capable of running bio-impedance spectroscopy and tomography applications (scientific jargon for looking inside things).

The Spectra imager was designed using a tiny two-inch PCB outfitted with 32 electrodes arrayed around a circular tank (AKA phantom) and uses a non-ionizing AC to produce image reconstructions of any conductive material placed inside, organic or otherwise.

The device functions by passing an AC wave through the object inside the container, where the electrical impedance magnitude and phase are measured by the electrode array. The process is run several times over, which provides a tomographic reconstruction of the object between 80–80KHz.

All in all, Spectra is capable of producing time series impedance measurements, bio-impedance spectroscopy, along with electrical impedance tomography, using the open-source software, which packs three types of tomographic reconstructions — Graz Consensus, Gauss-Newton Method, and Back Projection.

Mindseye Biomedical recently provided an update about their revamped OpenEIT software platform, making it easier to install and use straight out of the gate. Traditional EIT (Electrical Impedance Tomography) typically use computational platforms such as MATLAB to analyze recordings, which is expensive and time-consuming.

The OpenEIT package, on the other hand, uses an intuitive dashboard that connects directly to Spectra, reconstructing images in real-time, and allowing you to use the platform’s firmware to sweep through frequencies for bioimpedance spectroscopy continuously.

Previous bugs that were encountered running algorithms in real-time while streaming Bluetooth have been fixed, and you can now connect Spectra via USB dongle to directly stream to your laptop. Minseye Biomedical has also uploaded detailed instructions, tutorials, and more to their GitHub page to get you up and running with the imager. Finally, they are holding a workshop in San Francisco on April 18th, where neuroscientist Jean Rintoul and others will present tutorials and demonstrations using the Spectra platform, and will also offer a webinar on April 25th — those interested can sign up here.

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