A one millimeter electromagnetic motor (.039")

Recently, it was decided that it might be advantageous to have electric motors small enough to go in human arteries and other small places to do various jobs. The procedure followed was to carefully go from known methods step by step to the desired diameter of one millimeter. Motors were made and tested successively at 4.5 mm, 2.5 mm, 1.5 mm and 1 mm. It turned out that normal motor design methods were applicable, and the main problems were making and handling the tiny pieces. Calculation and very abbreviated tests seem to indicate that smaller motors could be made. This and previous work on very small motor designs seems to indicate that the torque goes down slightly faster than the cube of the diameter.<>