Decades ago, i invented a perpetual motion machine based on the Casimir effect. You have this setup with two plates or whatever, with the distance between them

Decades ago, i invented a perpetual motion machine based on the Casimir effect. You have this setup with two plates or whatever, with the distance between them suitable for the Casimir effect to arise, pulling the plates together. One of the plates is movable, and you have a mechanism for extracting work when the force pulls the plate inward, and for moving the plate back out - maybe the plate is on a string attached to a motor-generator, or to a magnet moving in a coil or something. The trick is that you make one of the plates out of a semiconductor. The Casimir effect only arises between conducting plates. So you can turn the effect on and off using a voltage on the semiconducting plate. So, you can apply a voltage to turn the effect on, let the moving plate move inwards, extracting work as it does so, then withdraw the voltage to turn the effect off, move the plate outwards, this time not needing to do work against the force, then repeat the cycle. Obviously, this won't work. Mostly it won't work for engineering reasons involved in the scale of the thing. But there must also be a reason why it wouldn't work in principle. I don't know what that reason is.