Swimming prosthesis improves strokeProsthetic legs gave 56-year-old Jeffery Evans the ability to walk, but the exercise eventually proved too hard on his legs, so he took up swimming instead. Swimming, however, also has been a challenge. Luckily, Evans was able to sponsor a senior project that enabled mechanical, industrial and manufacturing engineering students to develop a prosthetic swim fin to further perfect and improve the efficiency of his stroke. The fin designed by students Alex Demith, Ian Lawson, and James Cooper is allowing Evans to keep swimming and stay fit while improving his mobility.

The team wanted to develop a fin that replicated the motion of a balanced swim stroke. Materials for fin construction had to be resistant to chlorine, since Evans often swims in a chlorinated pool. Neoprene wetsuit material, ethylene vinyl acetate foam, and plastic zippers proved most effective. The buoyancy of the foam proved advantageous because it added balance and improved Evans’ upstroke.

The team rapidly created and tested 12 prototypes throughout the design phase to determine how effectively each iteration augmented Evans’ stroke. The students finally settled on a combination of two prototypes. The selected design features multiple elongated triangular foam fins that protrude from the surface of the main fin. Neoprene pockets hold multiple smaller foam fins in place.

A backstroke-capable fin remained elusive to the team, but the final design was successful in strengthening Evans’ freestyle and breast strokes. The team considered the motion successfully balanced when Evans was able to swim in a straight line.

Inspired by the swim fin project, Demith says he has considered further schooling to specialize in prosthetics and orthotics.

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