Active cooling of twisted coiled actuators via fabric air channels.
Alex Lizotte, Ana Luisa Trejos
PMID 36530795WHAT IT FOUND
A fabric channel with forced air cooled artificial muscles for wearable devices faster than passive cooling, but it reduced their movement and slightly increased heating.
The work tested bench prototypes only, not stroke patients or rehabilitation exercises.
Key findings
01Active cooling with the channel reduced cooling time by 42% compared with passive cooling without the channel, from 21.71 ± 1.24 s to 12.54 ± 2.31 s.
02The cooling benefit came with costs: heating time increased and the actuator's useful shortening distance decreased.
03For a 4-ply actuator, the 10 × 8 channel had the best balance of cooling time, heating time and useful shortening distance among the tested sizes.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
No people were tested. The work measured artificial muscles on a bench, not stroke patients or rehabilitation exercises. The channel was not integrated into a wearable garment, so comfort, fit and real use were not tested. The pump was noisy, approaching the level of a normal conversation, which may be hard to ignore for some patients. The best channel was the largest tested, and larger channels may protrude too much or limit how many channels fit on a limb. Artificial muscles and channels varied from fabrication, and placing the muscle in the channel changed the results. The no-channel active cooling setup cooled faster but could burn the user, so it is not a usable wearable comparison. Room temperature varied, and the temperature sensor may have read slowly because of incomplete contact.
Declared interests
The work was funded by the Natural Sciences and Engineering Research Council of Canada. The supplied text does not list other conflicts of interest.
The easy way to misread this
Do not read the 42% cooling time reduction as evidence that wearable robotic therapy helps stroke recovery. The study tested artificial muscles without patients, and the channel also increased heating time and reduced useful shortening distance.