A clever idea, and one tried extensively in the 1970s! For more
information, see
www.gumption.org/mcip/paper.html :

"Researchers have long dreamed of creating new vas-based methods. In the
1970s, a variety of elaborate metal valves were created, most of which either
punctured the vas (due to their inflexibility) or insufficiently prevented sperm
passage (Free 1978). Most of these methods (a few of which had only minor
problems) died for lack of funding or proponents. The past decade, however, has
brought a new crop of advances. Although these advances may seem less flashy
than
the magnetic valves and biogalvanic cells of old, they show many times the
promise for practical and immediate application."

- Elaine

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In a message dated 11/8/05 10:50:36 AM, usaf_dragongirl@... writes:


> I have had an idea about some sort of device which would act as a gate
> not allowing sperm to pass, which could be opened or closed via an
> external magnet placed over the device. The difference in polarity
> would make the gate open or closed.
> I don't know if this is a possible idea, but I just wanted to throw it
> out there.
>



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