A dual-functional capsule robot for drug delivery and tissue biopsy based on magnetic torsion spring technology

Abstract

Wireless capsule endoscopy (WCE) has the potential to fully replace conventional wired counterparts for its low invasiveness. Recent studies have attempted to expand the functions of capsules toward this goal. However, limitations in space and energy supply have resulted in the inability to perform multiple diagnostic and treatment tasks using a single capsule. In this study, we developed a dual-functional capsule robot (DFCR) for drug delivery and tissue biopsy based on magnetic torsion spring technology. The delivery module was shown to rotate the push rod with a thrust of 894 mN to release approximately 0.3 mL of semisolid drug. The biopsy module used a built-in blade to cut tissue with a shear stress of 22.87 MPa, producing a sample of approximately 1.8 mm3. Additionally, a five-degree-of-freedom permanent magnet drive system was developed. By adjusting the strength of the unidirectional magnetic field generated by an external magnet, the capsule can be wirelessly controlled to sequentially trigger the two functions. Ex vivo tests on porcine stomachs confirmed the feasibility of the prototype capsule (12 mm in diameter and 45 mm in length) in active movement, medication, and tissue biopsy. The newly developed DFCR further expands the clinical application prospects of WCE robots in minimally invasive surgery.