Micromotors

Micromotors are miniature electric motors designed to produce rotational or linear motion at small scales, typically ranging from tens of micrometers to a few millimeters in size. They are used in settings where conventional motors are impractical due to space, weight, or energy constraints. Micromotors can be categorized by actuation method, including electric motors powered by micro-scale circuits (such as brushless DC, brushed DC, and stepper designs), ultrasonic motors driven by high-frequency vibrations, piezoelectric motors that convert electric field-induced strain into motion, and magnetic motors that use external magnetic fields to drive a rotor. Linear micromotors are also available.

Construction and operation of micromotors often rely on microfabrication techniques from MEMS (microelectromechanical systems), enabling integration with sensors and other circuitry. Common materials include silicon, ceramics, and polymers. Bearings and lubrication are critical at micro scales, with some designs minimizing wear through magnetic bearings, air bearings, or purely non-contact operation. Power sources range from miniature batteries and wireless power transfer to externally applied magnetic fields. Control systems use specialized electronics and feedback from integrated sensors to regulate speed and torque.

Applications of micromotors span several fields. In MEMS and microfluidics, they actuate valves, pumps, and mixers within tiny fluidic networks. In micro-robotics, they provide actuation for joints, wheels, or grippers in small robots. Medical devices use micromotors for targeted drug delivery or minimally invasive tools, and in optics they drive micro-positioners or switches. Challenges include fabrication complexity, limited torque and efficiency, wear and heat management, and integration with power and control systems. Ongoing research seeks to improve reliability, biocompatibility, and performance in real-world environments.