Moving air with spinning blades is the most popular way, but it is not the only way. Using the PCB actuator technology he has been working on for the past few years, [Carl Bugeja] built a small electromagnetic flapping fan using a custom flexible PCB.
Inspired by expensive piezoelectric fans ($400 for a 30mW fan), [Carl] wanted to see if a cheaper alternative could be made. Using a similar design to his other PCB actuators, he had a custom flexible PCB made with an integrated coil, which can flex on two thin supports. These supports also contain the power traces for the coil. By sticking the base of the PCB between two neodymium magnets, it can flap back and forth when driven by an alternating current. It produces a bit of airflow, but nearly enough to be useful. The power traces in the thin supports also break after an extended period of 180° flapping.
Although this probably won’t be a viable replacement for a rotary fan, it would be interesting to see how far one can push this approach by optimizing the design and magnet arrangement.
[Carl] has been experimenting with a variety of applications for his PCB actuators, from tiny flopping robots to tiny speakers, he doesn’t seem to be running out of ideas. A flip-dot display might be interesting…