Journal of Micro-Bio Robotics最新文献

Soft, magnetically actuated robots offer promising potential for medical applications due to their simple fabrication, controllability, cargo loading ability and flexibility. This research focuses on the design, modeling, and behavior of soft, millimeter-scale filamentous robots composed of Gelatin Methacrylate (GelMa) hydrogels and embedded with micromagnets for magnetic actuation. These robots are designed for navigation within the human urinary tract. The study investigates two distinct configurations: screw-like and fin-like robots, each responding differently to an external rotating magnetic field. The screw-like robots propel forward through synchronized helical motion, while the fin-like robots rely on interaction with surrounding surfaces for crawling motion. Experimental frequency response tests reveal that fin-like robots exhibit three times faster motion than screw-like robots in confined environments, reaching velocities of up to 18 mm/s. Additionally, the influence of micromagnet location inside the filaments on their propulsion dynamics is explored, highlighting the potential for optimized performance in medical applications requiring navigation through narrow channels, such as the ureter. Further optimization is proposed to enhance control and performance in more complex biological environments.

Supplementary information: The online version contains supplementary material available at 10.1007/s12213-025-00188-1.

Cells are building blocks of living systems. Spatio-temporal mapping of local biophysical changes within cells can lead to novel insights into various biological events. As demonstrated in previous works, successful internalization, controlled manipulation, bio-compatibility, and surface-functionalization capabilities make the helical magnetic nanobots, an ideal candidate for local intracellular measurements. In this work, we focus on both qualitative and quantitative understanding of the mechanical properties of the intracellular medium based on intriguing new observations that emerge in the dynamics of the helical nanobots, driven inside cells. Our studies show that orientational changes in the nanobots can be an important measure of the underlying anisotropy and local topographical confinements in the cell cytoplasm. Inside cells, the orientational differences (from the intended direction fixed by the magnetic drive) can sometimes be as high as 70-80 degrees, significantly higher than those expected for homogeneous Newtonian media. We find that correlating these orientational changes to the corresponding velocities of the nanobots can enable us to sense local confinements and boundaries in the cellular interiors. Also, the hydrodynamic pitch during propulsion significantly depends on the nanobot position inside cells. At times, the pitch can get as high as 700 nm (about 3-4 times higher than the hydrodynamic pitch in a Newtonian medium), showing the presence of local solid-like (elastic) behavior of the cell cytoplasm. Interestingly, the signature of intermittencies in dynamics and backward motion also shows up in the pitch measurements, highlighting the presence of local confinements and topographical variations. These studies demonstrate how the dynamics of the helical nanobots can be utilized to develop novel metrics for spatio-temporal mapping of mechanical variations inside cells.

Supplementary information: The online version contains supplementary material available at 10.1007/s12213-024-00176-x.

The field of microrobotics has emerged as a promising area of research with significant applications in biomedicine, both in vitro and in vivo, such as targeted cargo delivery, microsurgery, and cellular manipulation. Microrobots actuated with multiple modalities have the potential for greater adaptability, robustness, and capability to perform various tasks. Modular units that can reconfigure into various shapes, create structures that may be difficult to fabricate as one whole unit, and be assembled on-site, could provide more versatility by assembly and disassembly of units on demand. Such multi-modal modular microrobots have the potential to address challenging applications. Here, we present a biocompatible cylindrical microrobot with a dome-shaped cavity. The microrobot is actuated by both magnetic and acoustic fields and forms modular microstructures of various shapes. We demonstrate the use of these microrobots for cellular manipulation by creating patterns on a surface.

Supplementary information: The online version contains supplementary material available at 10.1007/s12213-024-00175-y.

Micro-and nanorobots have the potential to perform non-invasive drug delivery, sensing, and surgery in living organisms, with the aid of diverse medical imaging techniques. To perform such actions, microrobots require high spatiotemporal resolution tracking with real-time closed-loop feedback. To that end,  photoacoustic imaging has appeared as a promising technique for imaging microrobots in deep tissue with higher molecular specificity and contrast. Here, we present different strategies to track magnetically-driven micromotors with improved contrast and specificity using dedicated contrast agents (Au nanorods and nanostars). Furthermore, we discuss the possibility of improving the light absorption properties of the employed nanomaterials considering possible light scattering and coupling to the underlying metal-oxide layers on the micromotor's surface. For that, 2D COMSOL simulation and experimental results were correlated, confirming that an increased spacing between the Au-nanostructures and the increase of thickness of the underlying oxide layer lead to enhanced light absorption and preservation of the characteristic absorption peak. These characteristics are important when visualizing the micromotors in a complex in vivo environment, to distinguish them from the light absorption properties of the surrounding natural chromophores.

Supplementary information: The online version contains supplementary material available at 10.1007/s12213-023-00156-7.