A research team led by Professor Bin Yang at Shanghai Jiao Tong University has developed an ultrasonic microrobot able to travel rapidly in both directions within narrow pipes. The device, detailed in Nano-Micro Letters, pairs frequency-modulated ultrasonic actuation with a flexible piezoelectric composite to advance inspection systems for confined environments.

The robot uses movement inspired by a centipede's retrograde wave gait, transforming ultrasonic vibration into traveling bending waves that create thrust against pipe walls. Its lead zirconate titanate film is integrated with a flexible PET base by MEMS fabrication and sealed with parylene-C, yielding a compact 24 mm by 7 mm by 210 micrometer form weighing just 80 mg.

Direction is switched by adjusting the driving frequency, enabling smooth forward and reverse motion without mechanical changes. The robot achieves a peak speed of 81 cm per second at a low voltage of 3 Vp-p, outperforming reported piezoelectric microrobots and requiring much less power than dielectric elastomer models.

This microrobot can navigate 4 mm-high pipes, climb slopes up to 24.25 degrees, and carry loads more than 36 times its own weight. Robust performance was demonstrated in glass, steel, and PVC pipes and across water, showing effective sealing and resilience.

A micro-endoscope camera provides real-time imaging inside pipelines, supporting inspection and diagnostics. The platform has application potential in industrial and biomedical microdevices where miniature, agile robots are essential.

Future work will address autonomous operation by integrating onboard power, wireless modules, and micro-batteries. Expanding sensing, imaging, and manipulation capabilities could transform the system into a multifunctional inspection robot. This approach, with its low power demands and scalable construction, lays groundwork for advanced microrobotics in industrial and medical use.

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