Design and Analysis of a Three-Dimensional Spindle-Shaped Receiving Coil for a Targeted Therapy Capsule Robot in the Intestine

Capsule robots capable of taking wireless power-transfer systems for diagnosis in the intestine enable the ability to avoid invasive detection, which causes damage to tissue. A targeted therapy capsule robot based on a wireless power-transfer system could move actively in the intestine, implementing diseases detection and drug delivery. Compared with traditional telescope, the capsule robot explores without pain to patients. However, the insufficient power supply has become a big issue for a targeted therapy capsule robot. To address this problem, we proposed a new type of three-dimensional spindle-shaped receiving coil that can couple well with unidirectional magnetic fields and supply sufficient energy even when there is a misalignment in position and angle, owing to which the electromagnetic energy decays quickly. The proposed receiving coil could be embedded on the capsule robot, suitable for the capsule size Φ15 mm × 25 mm. To obtain the maximum energy in three-dimensional space, an optimization model was built. The parameters of the receiving coil were optimized and analyzed. Then, the designed receiving coil was verified with an energy-transfer stability analysis based on both attitude angle and position in a bench test. Furthermore, a curved pipe experiment was conducted using a capsule robot prototype with the proposed three-dimensional spindle-shaped receiving coil. The results demonstrated that stable and sufficient power could be supplied by the proposed receiving coil for the capsule robot at any position and any attitude angle between transmitting and receiving coils.