An accurate model for size optimization of an embedded permanent magnet for drug delivery with capsule robots

An actively controlled drug delivery system (DDS) is an essential module to be included in the next generation of capsule endoscopy. Its development will allow physicians to perform non-invasive procedures and treat diseases in the digestive system. Despite many attempts to magnetically actuate internal permanent magnets (IPMs) embedded in prototype capsule robots to enhance their capabilities, further miniaturization and optimization of the IPMs are required to achieve more efficient torque transmission while minimizing the size of the IPMs. In this paper, we optimize the IPM´s size to obtain a high magnetic torque that activates a DDS which is based on an overly miniaturized slider-crank mechanism. The IPM is optimized by means of analytical models. Our experimental results, which are in agreement with the analytical results, show that a high torque and force are generated on the piston of the DDS that expels drug out of a reservoir when an optimized IPM is embedded in the capsule robot.