School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.
Biomed Microdevices. 2012 Feb;14(1):165-78. doi: 10.1007/s10544-011-9594-7.
Capsule endoscopy is a promising technique for diagnosing diseases in the digestive system. Here we design and characterize a miniature swimming mechanism that uses the magnetic fields of the MRI for both propulsion and wireless powering of the capsule. Our method uses both the static and the radio frequency (RF) magnetic fields inherently available in MRI to generate a propulsive force. Our study focuses on the evaluation of the propulsive force for different swimming tails and experimental estimation of the parameters that influence its magnitude. We have found that an approximately 20 mm long, 5 mm wide swimming tail is capable of producing 0.21 mN propulsive force in water when driven by a 20 Hz signal providing 0.85 mW power and the tail located within the homogeneous field of a 3 T MRI scanner. We also analyze the parallel operation of the swimming mechanism and the scanner imaging. We characterize the size of artifacts caused by the propulsion system. We show that while the magnetic micro swimmer is propelling the capsule endoscope, the operator can locate the capsule on the image of an interventional scene without being obscured by significant artifacts. Although this swimming method does not scale down favorably, the high magnetic field of the MRI allows self propulsion speed on the order of several millimeter per second and can propel an endoscopic capsule in the stomach.
胶囊内镜是一种有前途的诊断消化系统疾病的技术。在这里，我们设计并描述了一种微型游泳机制，该机制利用 MRI 的磁场来推动和为胶囊提供无线动力。我们的方法利用 MRI 中固有的静磁场和射频（RF）磁场来产生推进力。我们的研究集中在评估不同游泳尾巴的推进力，并实验估计影响其大小的参数。我们发现，当由提供 0.85 mW 功率的 20 Hz 信号驱动、长约 20 毫米、宽 5 毫米的游泳尾巴位于 3 T MRI 扫描仪的均匀磁场内时，它在水中能够产生 0.21 mN 的推进力。我们还分析了游泳机构和扫描仪成像的并行操作。我们分析了由推进系统引起的伪影的大小。我们表明，当磁微游泳者推动胶囊内窥镜时，操作员可以在介入场景的图像上定位胶囊，而不会被明显的伪影遮挡。尽管这种游泳方法不太适合缩小规模，但 MRI 的高磁场允许以每秒几毫米的速度进行自我推进，并可以推动胃内的内窥镜胶囊。
