Micro-rocket robot with all-optic actuating and tracking in blood

Micro/nanorobots have long been expected to reach all parts of the human body through blood vessels for medical treatment or surgery. However, in the current stage, it is still challenging to drive a microrobot in viscous media at high speed and difficult to observe the shape and position of a single microrobot once it enters the bloodstream. Here, we propose a new micro-rocket robot and an all-optic driving and imaging system that can actuate and track it in blood with microscale resolution. To achieve a high driving force, we engineer the microrobot to have a rocket-like triple-tube structure. Owing to the interface design, the 3D-printed micro-rocket can reach a moving speed of 2.8 mm/s (62 body lengths per second) under near-infrared light actuation in a blood-mimicking viscous glycerol solution. We also show that the micro-rocket robot is successfully tracked at a 3.2-µm resolution with an optical-resolution photoacoustic microscope in blood. This work paves the way for microrobot design, actuation, and tracking in the blood environment, which may broaden the scope of microrobotic applications in the biomedical field. Biotechnology: Laser-powered robots rocket through the bloodstream Researchers now report that lasers can be used to safely move tiny robots in the blood. Dr. Dengfeng Li and Mr. Chao Liu from the City University of Hong Kong in China and colleagues used 3D printing to create microscale tubes, connected to resemble a central rocket with two side boosters attached. After applying a light-absorbing gold coating to the micro-rockets, the team irradiated the device with laser pulses. The resulting thermal gradient along the length of the tubes propelled the device steadily through solutions with high viscosity, such as blood. Furthermore, the gold coating generates ultrasonic signals that can be spotted through photoacoustic microscopic techniques. Injections of the micro-rockets into blood revealed they could be tracked with microscale resolution as they were directed to flow through the bloodstream.