Virtually all electric motors work in the same way: electrical current is connected to an electromagnet by a brush that makes contact with a central commutator. That’s split into two or more radially-symmetrical sections, so that the shaft continues to spin as each section receives power. A stepper motor does the same thing, but with an unequal number of teeth between the stator and rotor — allowing it to be moved a single step at time. Bobricus has taken that concept and applied it to a PCB to create a micro car track called Ant Highway.
To be more accurate, Bobricus has taken a 3-phase linear motor, formed that into a circular shape, and printed the coils directly onto a circuit board. The PCB is 10x10cm, which means the diameter of the motor “track” is slightly smaller than that. Unlike traditional wound coils, the coils for this motor are flat. They’re formed from PCB traces that cross between the two layers of the board in a spiral pattern. Because this is a 3-phase motor, there are three coils that continuously overlap each other. But cycling power through those three coils, a magnet can be pulled around the track in either direction.
The power to the coils is controlled by a Microchip ATtiny10 8-bit microcontroller through three MOSFETs. The entire motor only consumes about 1W of power, and remains at a stable temperature during operation. Bobricus reports that it has a precision of 0.63mm per step. The moving magnets can be attached to whatever the user likes to create an animated display. But, the truth is that this really doesn’t have a practical application yet. It does, however, demonstrate what’s possible with PCB-based motor designs.