The origin of the self stirring mug
When I was at a friends factory, I accidentally saw a cup that stirred by magnet particles.
After deeper understanding and discussion, I also relized the shortcomings of the principle cup, the small rotating magnet particles may be Swallowed by children, another questions is highly thick liquid cannot be stirred.
I suddenly wondered whether these problems could be solved if propeller stirring was used.
During the discussion with the structural engineer, we realized that preventing water leakage might be the key concern with the propeller solution.
After many trials,fortunately, we solved the problem by using a close contact between the silicone and the linkage rod and by squeezing the cup with an external force, accroding to the solution of houseboats propeller.
That is the origin of self stirring coffee mug.