DILLON CHEN

THE BODY IN SPACE

In a free fall gravity environment, the body adapts to the lack of gravitational pull by eliminating muscle tissue. Muscle mass decreases at a rate as high as 5% a week, most notably in the leg and back muscles that experience less load bearing. To combat muscle atrophy, astronauts are required to exercise vigorously aboard the station in order to preserve muscle mass.

Electromyography (EMG) is a contemporary technique used to monitor muscle health. Adhering several surface EMG electrodes to large muscle groups detect electrical signals as the muscles contract. The Myomonitor, developed by Delsys Inc., for example, is an electrode to skin interface that's been evaluated by NASA to study the muscles of astronauts in free fall gravity.

Observing the Myomonitor’s tangle of wires and electrodes, my team sought to streamline an attachment method that would allow astronauts to monitor their muscle health during exercise without any obstruction.

ACOUSTIC MYOGRAPHY

Our engineer, Eesha, proposed the use of an acoustic sensor to test for muscle fatigue. Acoustic myography records the low frequency sounds generated by the muscles during contraction. This sound is observed to be between 10-50 Hz, with a peak around 25 Hz. The amplitude of this signal decreases as stress in a particular muscle increases. This phenomenon can be used to monitor muscle health without having to dip into the cost of electromyography. 

A low frequency acoustic sensor will be incorporated into the harness and placed in direct contact against the skin. Muscle contractions during exercise or daily motions will be recorded on a data acquisition system. The advantage of acoustic myography lies in its non-invasive technique that is easy to use and operate for the purpose of proving our design concept. 

Two large muscle groups, the pectorals and quadriceps, have been targeted for monitoring.