Magnetically maneuverable microrobot using acoustic bubbles for targeted drug delivery technology.

This paper proposes a new type of magnetically maneuverable microrobot using acoustic bubbles aimed at multiphase drug delivery to target tissues inside human blood vessels. The proposed microrobot utilizes two bubbles embedded in a microtube to contain solid and liquid drugs and uses magnetic actuation to transport the drugs to the target tissue. And when an acoustic wave was applied to the bubbles, the drugs can be released into the target tissues by microstreaming generated from acoustically oscillated bubbles. The proposed microrobot consists of the microtube with bubbles and a liquid metal, which was fabricated using microfabrication technology based on an ultra-precise 3D printer. We conducted experiments to transport the microrobot to a specified location using a permanent magnet. Using a high-speed camera, we carried out the conditions for releasing the drug according to the length of the bubbles, the frequencies of the acoustic wave, and the viscosities of the drugs. As proof of concept, the proposed microrobot is demonstrated by transporting and releasing liquid and solid drugs to target locations in microchannels that mimic blood vessels. Although the proposed microrobot has a simple structure, it is expected to improve the efficiency of targeted drug delivery due to transporting drugs to the target tissues and manipulating multiphase drugs.