Photothermal-driven water-gliding microrobots based on fully integrated flexible sensors with heterogeneous wettability

Bionic water strider robots (BWSRs) have been a hot spot in research due to their unique biological inspiration and versatile applications in environmental monitoring. However, creating aquatic micro-robots with combined structure and function that can walk freely and perceive environmental information on water surfaces remains a challenge. Herein, self-propelled and integrated aquatic microrobots that can be remotely controlled by light and wireless environment detection are designed and fabricated by combining the actuating polydimethylsiloxane (PDMS)/carbon nanotube (CNT) substrate with heterogeneous wettability and the fully integrated wireless sensors. The substrate generates thrust on water through the photothermal Marangoni effect, serving as the propulsion system for this water-gliding microrobot. The heterogeneous wettability design features the robot with a hydrophobic body and four hydrophilic footpads. The hydrophobic body creates an air gap between the device and water, providing waterproof protection for electronics, making the robot move faster with smaller power and enabling greater load-carrying capacity. The hydrophilic footpads help the robot stand firmly on water, resisting overturn by waves and also enable modular assembly between robots. The load ability of a typical robot is 1,089% of its weight, resulting in the manufacture of microrobots with fully integrated visible light sensors and Bluetooth (BT) chips that can be steered by near-infrared laser. Hopefully, this strategy shall help to develop untethered aquatic robots with sophisticated actuation and wireless sensing for complex aquatic environments.