Just about everything that moves uses some sort of rigid actuation device. Most often, those are simple electric motors. But that also includes hydraulics, pneumatics, and others. It’s pretty rare to have actuators made from flexible materials, but that is exactly what Carl Bugeja has made a name for himself building. Most of his projects utilize flexible PCBs (Printed Circuit Boards) as electromagnetic coils that are attracted to permanent magnets when current runs through them. Now Bugeja has applied that same concept to paper with this flapping paper butterfly.
Any time electricity flows through a wire — or anything else — an electromagnetic force is generated. Usually that force is small enough that it can be ignored. But, by forming a wire into a tight coil, a significant electromagnet can be created. That’s the underlying principle behind a huge range of technologies, and is what makes electric motors spin. Those coils can also be made on PCBs, which is how Bugeja’s other flexible actuators have worked. For this project, he is using the same basic technique to create coils on paper that allow it to be actuated.
To do that, Bugeja first acquired some conductive ink pens. You can use those to draw lines on paper that act like wires. He then tested each of the pens to determine how much resistance their ink had. After finding out that information, he was able to calculate the length and size of the coils he’d need. Those coils were then drawn onto the paper using a Cricut plotting and cutting machine. Finally, the shape of the butterfly was cut out. By applying voltage to the coils in pulses, then wings of the butterfly are pulled towards permanent magnets so that they flap. The butterfly is really just a demonstration of the idea, and proves that paper actuators are feasible.