Wireless flow-powered miniature robot capable of traversing tubular structures.

Wireless millimeter-scale robots capable of navigating through fluid-flowing tubular structures hold substantial potential for inspection, maintenance, or repair use in nuclear, industrial, and medical applications. However, prevalent reliance on external powering constrains these robots' operational range and applicable environments. Alternatives with onboard powering must trade off size, functionality, and operation duration. Here, we propose a wireless millimeter-scale wheeled robot capable of using environmental flows to power and actuate its long-distance locomotion through complex pipelines. The flow-powering module can convert flow energy into mechanical energy, achieving an impeller speed of up to 9595 revolutions per minute, accompanied by an output power density of 11.7 watts per cubic meter and an efficiency of 33.7%. A miniature gearbox module can further transmit the converted mechanical energy into the robot's locomotion system, allowing the robot to move against water flow at an average rate of up to 1.05 meters per second. The robot's motion status (moving against/with flow or pausing) can be switched using an external magnetic field or an onboard mechanical regulator, contingent on different proposed control designs. In addition, we designed kirigami-based soft wheels for adaptive locomotion. The robot can move against flows of various substances within pipes featuring complex geometries and diverse materials. Solely powered by flow, the robot can transport cylindrical payloads with a diameter of up to 55% of the pipe's diameter and carry devices such as an endoscopic camera for pipeline inspection, a wireless temperature sensor for environmental temperature monitoring, and a leak-stopper shell for infrastructure maintenance. Editor's summary: Millimeter-scale robots that are capable of traversing through pipes for maintenance and inspection often rely on external power, but this dependence limits the robot's operational range and environment. Conversely, pipe inspection robots with onboard powering and actuation units cannot be scaled down to the millimeter scale. As an alternate power source, Hong et al. developed a miniature robot that relies on environmental power to traverse a pipeline. The wheeled robot, equipped with an internal impeller, converts the fluid flow in the tube into mechanical energy. An external magnetic field can switch the direction the impeller rotates, enabling movement both with and against direction of flow. Flexible wheels enable the robot to traverse complex pipe shapes with changing diameter. By using flow power within the pipe, this robot can move long distances and perform for long durations. —Melisa Yashinski [ABSTRACT FROM AUTHOR]