Size‐Dependent Locomotion Ability of Surface Microrollers on Physiologically Relevant Microtopographical Surfaces

Abstract

Controlled microrobotic navigation inside the body possesses significant potential for various biomedical engineering applications. Successful application requires considering imaging, control, and biocompatibility. Interaction with biological environments is also a crucial factor in ensuring safe application, but can also pose counterintuitive hydrodynamic barriers, limiting the use of microrobots. Surface rolling microrobots or surface microrollers is a robust microrobotic platform with significant potential for various applications; however, conventional spherical microrollers have limited locomotion ability over biological surfaces due to microtopography effects resulting from cell microtopography in the size range of 2–5 µm. Here, the impact of the microtopography effect on spherical microrollers of different sizes (5, 10, 25, and 50 µm) is investigated using computational fluid dynamics simulations and experiments. Simulations revealed that the microtopography effect becomes insignificant for increasing microroller sizes, such as 50 µm. Moreover, it is demonstrated that 50 µm microrollers exhibited smooth locomotion ability on in vitro cell layers and inside blood vessels of a chicken embryo model. These findings offer rational design principles for surface microrollers for their potential practical biomedical applications.

Multi-level magnetic microrobot delivery strategy within a hierarchical vascularized organ-on-a-chip

“…The influence of the microtopography on spherical microrollers with varying sizes was investigated through computational fluid dynamics simulations and experiments in ref. 41, revealing that the significance of the microtopography effect diminishes as the size of the microrollers increases. The three-dimensional nature of the vascular system poses an additional challenge in the movement of magnetic particles.…”

Janus microparticles-based targeted and spatially-controlled piezoelectric neural stimulation via low-intensity focused ultrasound

“…These results indicate that FUS intensity values used in this study are not sufficient to evoke significant thermal or mechanical effects that might lead to stimulation of primary hippocampal neurons, especially >10 Hz neural stimulation 40 , 46 – 49 . In addition, we calculated the momentarily stress on the cells induced by the movement of the PEMPs on the cellular layer 50 (Supplementary Note 2 ). The calculations revealed that the forces due to propulsion of the PEMP and gravitation were <50 pN, and corresponding pressure of <50 Pa with the assumption of 1 μm 2 contact area between the PEMP and neurons.…”

Magnetic Mesoporous Janus Microrollers for Combined Chemo‐ and Photothermal Ablation Therapy

“…In our study, we sought to expand the medical and pharmaceutical applications of microrollers by focusing on their biological characterizations. While past research concentrated on mi-croroller locomotion and physics, [10][11][12][13][14]73,74] we aimed to broaden their medical and pharmaceutical relevance. Our study stands out for its unique focus on combinational therapy, active magnetic targeting, and enhanced drug dissolution rates integrated into a single microroller platform.…”