By Jordan Gaither | Updated Mar 24, 2022
Constructing a lightweight robot that moves independently is a rewarding project for hobbyists. A bristlebot—a tiny robot that rolls on the bristles of a toothbrush head—offers an engaging way to explore basic mechanics, electronics, and motor control without complex circuitry.
Carefully trim the bristled head of a toothbrush, leaving only about 1/8‑inch of the neck attached to the head. This remaining neck will serve as the mounting platform for the motor.
Place a thin strip of double‑sided sticky foam over the top of the bristle head. The foam provides a smooth, secure surface for attaching the motor while keeping the bristles—our robot’s “feet”—free to move.
Solder two short lengths of sturdy copper wire to the terminals of a 3‑volt pager or cell‑phone motor. Allow the solder joints to cool completely before proceeding.
Mount the motor onto the sticky foam, orienting the shaft so it faces away from the trimmed neck. Ensure the motor is centered on the foam and that the shaft does not contact the toothbrush’s edge.
Lay one copper lead flat on the foam, extending it backward from the motor. Firmly press a 3‑volt coin‑cell battery onto this lead.
Touch the remaining copper lead to the top of the battery. The motor will start vibrating, propelling the robot forward at a surprisingly smooth speed.
If the motor, battery, or foam are not centered properly, the bristlebot may veer in circles or topple over. Re‑arrange the components and retry until the robot moves straight.
