It’s What’s on the Inside That Counts

EIT-kit shrinks and simplifies medical-grade imaging tools so that anyone can get a view of what is going on inside their body.

Nick Bild
3 years agoHealth & Medical Devices
EIT-kit (📷: J. Zhu et al.)

Personal health technologies have come a long way from the early days of simple step counters. Now watches, phones, and other wearable devices, can track all manner of physiological signals and raise an early warning about possible health problems. In order for these types of personal devices to be realized, miniaturization of sensors is a prerequisite.

Electrical impedance tomography (EIT) has historically relied on large, expensive equipment that required a good deal of expertise in order to operate. This has relegated technologies making use of EIT to the medical clinic and research lab. Accordingly, the ability of EIT to monitor the inner structure of the body has not been available to the individual via a consumer electronic device.

Researchers at MIT’s CSAIL and the Massachusetts General Hospital are working to change this situation with their work on EIT-kit. The toolkit that they have designed makes use of printed electronics and open source EIT image processing libraries to shrink the size of the hardware, and make it accessible to those without expert-level knowledge of EIT systems.

EIT’s ability to sense muscle activity make it ideal for monitoring muscle activity after an injury or surgery. The team also demonstrated devices built with the toolkit that can detect distracted driving, or recognize hand gestures made by the wearer.

The main components of EIT-kit are an extension to a 3D editor that allows for components to be 3D-printed, a custom EIT sensing motherboard for capturing measurements, a microcontroller library for automating EIT signal calibration, and an image reconstruction library that can be used to visualize the data. These components make it possible to design devices that are customized for specific use cases, different body locations, and even different individuals. Applications using two or four terminals, and with up to 64 electrodes are supported by the kit.

The team evaluated the performance of devices built with EIT-kit in a series of experiments. In these trials, they found that the device electrodes make contact with human skin in a way that is comparable to the tested gold standard ECG electrodes. In another trial, they tested the quality of the measured data by confirming that their device could detect the number, sizes, and shapes of objects placed within saline water (which approximates the conductivity of human skin). EIT-kit was found to accurately determine each of these metrics.

Because the EIT-kit was designed for portable applications, it runs on a five volt power supply, which limits the voltage measurement range of the system. The team believes that they can address this in a future revision by incorporating a voltage booster. They also plan to eventually provide pre-built applications, such that the toolkit can be used by individuals with less programming experience. With enhancements such as these, perhaps EIT-kit will find its way into the toolkits of professional engineers and makers alike in the future.

Nick Bild
R&D, creativity, and building the next big thing you never knew you wanted are my specialties.
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