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Building a robot the size of a cockroach requires rethinking every assumption of conventional mechanical and electrical engineering. At the centimeter scale, wire harnesses become unmanageable tangles, rigid chassis structures become disproportionately heavy, and conventional connectors dwarf the components they're meant to join. Rigid-flex PCBs offer a radical solution: Make the circuit board the skeleton.
Structural Electronics
This concept, sometimes called structural electronics, exploits a key property of rigid-flex PCBs: the ability to combine stiff regions that hold components with compliant flex regions that serve as joints. In practice, rigid-flex PCBs are replacing the bones and nerves of insect-scale machines. In a conventional robot, motors, sensors, and processors are mounted on separate rigid boards and connected by wires. In a structural electronics design, all of these elements share a single multilayer rigid-flex PCB that, when folded along its flex regions, becomes a three-dimensional electromechanical assembly.
The Harvard Microrobotics Laboratory has been a pioneer in this space. Its RoboBee platform, a sub-gram flying robot inspired by insect flight, uses a laminate manufacturing process called smart composite microstructures. Though not a PCB in the traditional sense, it shares the same underlying principle: a flat-fabricated sheet that folds into a functional 3D structure. Later iterations have moved toward true rigid-flex PCB approaches as commercial fabrication capabilities have improved.
The weight savings are dramatic. A wire harness connecting a dozen sensors to a central processor in a robot this small might weigh more than the motors themselves. By routing all interconnects through the PCB substrate, which must exist in the design anyway, that parasitic mass disappears entirely. The board does double duty as conductor and structure.
To continue reading this article, which appeared in the August 2026 issue of I-Connect007 Magazine, click here.
