Magnetically actuated micro-robotic systems for biomedical applications

Sijie Ran

doi:10.17918/00000291

Magnetically driven micro-robotics has drawn the attention of researchers due to its emerging importance in biomedical applications. This interest is partly due to the physics of transporting and manipulating microscopic objects in a complex environment and partly because of its promising applications, such as minimally invasive surgery, sensing and drug delivery. However, on the one hand the poor understanding of the physics behind microscopic objects in a complex environment, such as blood and soft tissue, limits the precision of control and manipulation of micro-robots in biomedical applications, whereas on the other hand it obstructs the development of a new mechanism to improve the translation rate of object when in the object is in small size. There is a critical need for technologies that provide a satisfactory methodology and model to achieve high translation rate and precise transport of micro-robots in the body. The few existing approaches suffer from fundamental defects and must be improved. This work focuses on developing a new methodology for transporting magnetically driven micro-robots in biomedical applications. The first part of the work discusses the development of a magnetically actuated swimming mechanism of colloidal particle aggregation in Newtonian fluid environment, which has potential application in the body environment, such as the bloodstream. The colloidal particles that are free to move in fluid can be an attractive swimming system due to their simplicity and ability to assemble in situ. A new mechanism of swimming that relies on only the rotation of the particles themselves is under development in this study, which compares favorably with the traditional dragging mechanism using external magnetic force, when the size of the colloidal particles is reduced. The second part focuses on the modeling of accurate and controlled movement of small, untethered objects within soft tissue. Modeling such movement is important, as in many practical situations position feedback might not be available all the time, and trajectory planning is often essential. A model of highly non-linear soft tissue force response to the movement of a spherical solid capable of rotation and translation via forces and torques applied by an external magnetic field is developed based on experimental observation. While these responses can be complicated by the multiple degrees of freedom, it is revealed that these additional degrees of freedom can reduce the required forces, minimizing tissue deformation and decreasing required forces. In conclusion, this work has developed a new methodology for transporting magnetically driven micro-robots. The new mechanisms and models could spur improvement in the translation rate, accuracy and control of micro-robotic movement in biomedical applications.

Magnetically actuated micro-robotic systems for biomedical applications

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Magnetically actuated micro-robotic systems for biomedical applications

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