Abstract
Light-powered microbots are tiny robotic devices propelled and controlled using highly focused laser beams. Ranging from a few microns to hundreds of microns in size, they are engineered to operate in different aqueous environments in microfluidic channels in a laboratory setting and eventually, within the human body. Some of the potential uses of these microbots are in diagnosis, controlled drug release, micromanipulations, and targeted drug delivery to mitigate the adverse effects of cancer treatment. Despite significant progress made in the development of this state-of-the-art technology, the translation to the clinical environment still remains a challenge. This study endeavors to bridge this gap by exploring the extensive capabilities of these microbots, moving one step closer to their potential biomedical applications. Here, we introduced a novel control mechanism utilizing a Near-Infrared (NIR) laser beam to manipulate the microbots as well as the sustained release of drugs at targeted locations in a fluidic environment while comprehensively addressing their design, fabrication, and preservation techniques. We utilized the two-photon polymerization (2PP) method for the complex microfabrication of these microdevices. Employing a modular Optical Tweezers (OT) setup, this study not only provides a cost-effective solution for scientific research but also offers the flexibility to seamlessly integrate additional functionalities into the system, such as fluorescent microscopy imaging, controlled drug release mechanism, calibration unit for force measurements, etc. The capacity to control the microbots with a low-power laser offers an untethered and highly precise method of performing various tasks in a physiological environment without damaging the delicate organelles. The control methodology involves the use of a spatial light modulator (SLM) and a galvanometer scanner (GS) to create the optical traps and drive the microbots. The efficacy of this control mechanism is demonstrated through a series of intricate in-plane manipulation tasks performed by the microbots, including path tracing along linear and circular patterns, rotation, and pivoting motions, among others. Along with working on the optical trap calibration, we also proposed a unique method for multiple trap calibration and the measurement of pico-newton level force using a quadrant photodiode (QPD) and video microscopy. This work provides a basis for optimizing the design and operation of light-controlled microbots in practical settings, demonstrating the extraordinary dexterity of these machines and their potential in biomedical applications.