Bioengineers printed microrocket with three nozzles which, due to the thermophoresis set a new record in the speed of movement among the microrobots to 2.8 mm per second. Using photoacoustic microscopy, scientists were able to observe the movement microrocket using model rubber vessel with the blood and tissues of the mouse ear. Article published in the journal Light: Science & Applications.
Scientists have for some time been experimenting with microrobots for the treatment in vivo. The most convenient way to deliver these robots to the organs via the blood vessels as the circulatory system runs through the human body. To date, the micro-robots are used for pinpoint drug delivery and treatment of tumors mainly in the stomach, intestinal tract and subcutaneous tissue. When designing such robots, scientists are faced primarily with the inefficiency of movement and low-resolution means of detection that are not possible to determine individual robot with dimensions less than one hundred micrometers.
Blood is a viscous and fast-flowing environment, which greatly complicates the work of the microrobot inside the body. Of existing microrobots for different driving forces sufficient speed is reached only micro-robots for chemical movement, but toxic reagents are not allowed to use it in the blood vessels. Common magnetic microrobots excellent in security and control, but low speed does not allow to use them even in the vessels with the slowest blood flow. Higher rate among non-destructive and non-toxic methods have the micro robots, moving through the light. The basic principle of such micro-robots is the asymmetry of their shapes, which upon irradiation with light of different parts of the microrobot heat differently and there is the phenomenon of thermophoresis — the body moves from the hot zone into a cooler.
The movement of individual microrobot in the blood vessels is necessary to monitor with high precision, which does not allow to achieve modern methods (CT and magnetic resonance imaging, x-ray, fluorescent and ultrasonic mapping). But recently, scientists have developed a method for photoacoustic tomography and successfully applied it to the observation of microcapsules filled with spherical microbots.
If Give Wang (Lidai Wang) with colleagues from the City University of Hong Kong printed microrocket with three nozzles to increase the efficiency of movement based on light. To check the operation under natural conditions, scientists have launched a model of microrobots in a rubber container filled with glycerol and bovine blood, as well as in the ear of anesthetized mice. This microrocket can accelerate to 2.8 millimeters per second and rotate at a speed of 138 degrees per second.