Whether they're patients with degenerative diseases or astronauts in weightless environments, there are some people who need to know if their muscles are wasting away. A new wearable could one day allow them to check, when and wherever they wish.
Although tape measures can be used to a certain extent, currently the only really precise means of measuring muscle size and volume within specific parts of the body incorporate clinic-based technologies such as MRI scans.
Led by electrical and computer engineering graduate fellow Allyanna Rice, a team of scientists at The Ohio State University set out to develop a smaller, less expensive, patient-usable alternative. The result is a wearable device that looks not unlike a conventional blood-pressure-measuring cuff.
It incorporates two electrical coils made out of conductive threads, which are sewn into the fabric in a stretchable zigzag pattern. One of these coils serves as a transmitter, and one serves as a receiver. Importantly, the size of the loop formed by each coil (when the device is wrapped around a limb) varies with the underlying muscle volume.
"We apply a time-varying current on the transmit coil, which generates a magnetic flux on the transmit coil. A magnetic flux is then induced on the receive coil, and this flux induces a voltage on the receive coil that we can measure," Rice explained to us. "The induced magnetic flux is dependent on the cross-sectional area of the coils. So, as the circumference of the limb increases, the overall magnetic flux and voltage on the receive coil will increase as well."
The device has so far been tested on 3D-printed leg molds which were filled with ground beef to simulate the calf muscle in an average-size person. It was found to accurately detect small-scale changes in overall limb size, and to be capable of measuring muscle loss of up to 51%.
It is hoped that once the tool is developed further, it could be wirelessly connected to an app which would record and deliver patients' self-administered readings to health care providers.
"We envision the patient putting on the device when they want to check muscle size, rather than wearing the sensor continuously," said Rice. "This could be daily, weekly or monthly, depending on the underlying condition contributing to muscle atrophy."
A paper on the NASA-supported research, which was co-authored by Prof. Asiminia Kiourti, was recently published in the journal IEEE Transactions on Biomedical Engineering.
Source: The Ohio State University
