Real-time 3D optoacoustic tracking of cell-sized magnetic microrobots circulating in the mouse brain vasculature

Mobile microrobots hold remarkable potential to revolutionize health care by enabling unprecedented active medical interventions and theranostics, such as active cargo delivery and microsurgical manipulations in hard-to-reach body sites. High-resolution imaging and control of cell-sized microrobots in the in vivo vascular system remains an unsolved challenge toward their clinical use. To overcome this limitation, we propose noninvasive real-time detection and tracking of circulating microrobots using optoacoustic imaging. We devised cell-sized nickel-based spherical Janus magnetic microrobots whose near-infrared optoacoustic signature is enhanced via gold conjugation. The 5-, 10-, and 20-mu m-diameter microrobots are detected volumetrically both in bloodless ex vivo tissues and under real-life conditions with a strongly light-absorbing blood background. We further demonstrate real-time three-dimensional tracking and magnetic manipulation of the microrobots circulating in murine cerebral vasculature, thus paving the way toward effective and safe operation of cell-sized microrobots in challenging and clinically relevant intravascular environments.

Automated summary

This study proposed a method to detect and track circulating microrobots in real-time using optoacoustic imaging, by designing cell-sized nickel-based spherical Janus magnetic microrobots and enhancing their near-infrared optoacoustic signature through gold conjugation. The microrobots of different diameters were successfully detected in both laboratory and blood-containing environments, demonstrating the ability to track and manipulate them in real-time in murine cerebral vasculature.