Johns Hopkins University, Laboratory for Computational Sensing and Robotics, Baltimore, MD, 21218, USA.
Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA.
Sci Rep. 2024 Oct 4;14(1):23123. doi: 10.1038/s41598-024-72615-5.
Miniaturization of medical tools promises to revolutionize surgery by reducing tissue trauma and accelerating recovery. Magnetic untethered devices, with their ability to access hard-to-reach areas without physical connections, emerge as potential candidates for such miniaturization. Despite the benefits, these miniature devices face challenges regarding force and torque outputs, restricting their ability to perform tasks requiring mechanical interactions such as tissue penetration and manipulation. To overcome magnetic actuation system-based force and torque limitations, this study proposes Variable Outer Radius Individually Addressable Coil Stacks (VORIACS), a novel magnetic actuation system optimized for high force output generation to magnetic devices within its workspace. The VORIACS marks significant improvements and breakthroughs in magnetic actuation within decimeter-scale workspace. The VORIACS is comprised of 12 coils that are optimized for 2D magnetic field generation under maximized power consumption of up to 12 kW. We implement six two-channel motor controllers, powered by six separate power supplies. Each of the twelve coils in the system is operated on its own motor-controller channel. This arrangement allows the system to exceed the magnetic forces and torques possible for single-coil versions of the same geometry. This study elaborates on optimizing, manufacturing, integrating, and demonstrating this system. Comparative analysis reveals that while a suboptimal, single-coil version of this system generates 0.31 N force (710 mT/m magnetic gradient magnitude), the VORIACS produces 1.673 N force (3834 mT/m magnetic gradient magnitude) on the same magnetic object placed 5 cm away from the coils. Moreover, the strong penetration force generated by VORIACS enables needle penetration to a mock gel that has the rigidity of liver tissue. In addition, we demonstrate the advantage of stacked coils with variable radii for magnetic field manipulability while maintaining the optimized force delivery property of the system, which improves control and could facilitate multi-tool manipulation. By enabling a fivefold increase in magnetic pulling force compared to its single-coil counterpart, VORICAS raises the potential penetration capabilities of untethered magnetic robotics in surgical procedures.
医疗工具的微型化有望通过减少组织创伤和加速康复来彻底改变外科手术。具有无需物理连接即可进入难以到达区域的能力的磁性无绳设备，成为这种微型化的潜在候选者。尽管有这些好处，但这些微型设备在力和扭矩输出方面面临挑战，限制了它们执行需要机械相互作用的任务的能力，例如组织穿透和操作。为了克服基于磁致动系统的力和扭矩限制，本研究提出了可变外半径可寻址线圈堆叠（VORIACS），这是一种优化的新型磁致动系统，用于在其工作空间内产生高力输出，以用于磁性设备。VORIACS 标志着在分米级工作空间内的磁致动方面取得了重大改进和突破。VORIACS 由 12 个线圈组成，这些线圈经过优化，可在高达 12kW 的最大功率消耗下生成 2D 磁场。我们实施了六个双通道电机控制器，由六个单独的电源供电。系统中的十二个线圈中的每一个都在其自己的电机控制器通道上运行。这种布置允许系统超过相同几何形状的单线圈版本的可能磁力和扭矩。本研究详细阐述了优化、制造、集成和演示该系统。比较分析表明，虽然该系统的一个次优的单线圈版本产生 0.31N 的力（710mT/m 磁场梯度幅度），但 VORIACS 在距离线圈 5 厘米的相同磁性物体上产生 1.673N 的力（3834mT/m 磁场梯度幅度）。此外，VORIACS 产生的强大穿透力使针能够穿透具有肝脏组织刚度的模拟凝胶。此外，我们展示了具有可变半径的堆叠线圈在保持系统优化的力传递特性的同时对磁场可操作性的优势，这提高了控制能力，并可能促进多工具操作。VORICAS 使磁拉力比其单线圈对应物增加了五倍，从而提高了无绳磁机器人在手术中的潜在穿透能力。
