Piezoelectric ultrasonic resonant motor with stator diameter less than 250 µm: theProteusmotor

Minimally invasive and in vivo surgery is limited by the ability to provide controllable and powerful motion at scales appropriate for navigation within the human body. A motor for in vivo microbot propulsion is presented with a stator diameter of φ250 μm, demonstrating the potential to directly drive a flagellum for swimming at up to 1295 rpm with a torque of 13 nN m. The motor uses coupled axial-torsional vibration at 652‐682 kHz in a helically cut structure excited by a thickness-polarized piezoelectric element. The output power is 4.25 μW, on the order of what is necessary to navigate small human arteries. (Some figures in this article are in colour only in the electronic version)