MAGNETICALLY ACTUATED CAPSULE FOR TARGETED DRUG DELIVERY, MICROBIOME SAMPLING, AND TISSUE BIOPSY IN THE GASTROINTESTINAL TRACT

Abstract

In recent times, there has been a huge focus on developing minimally invasive procedures as they reduce trauma, cause less pain, lead to faster recovery, and fewer complications. Wireless capsule endoscopes were introduced to conduct minimally invasive disease diagnosis inside the Gastrointestinal (GI) tract. These capsules consisted of a camera that could take multiple images of the GI tract and could be interpreted outside by the doctor. However, these capsules lack components for active control. Adding additional capabilities, such as therapeutic and diagnostic functions to these capsules can lead to solving problems inside the GI tract in a less invasive manner.

This thesis introduces a versatile magnetically actuated robotic capsule that consists of magnetic components for active control. A magnet-spring mechanism has been developed that can be triggered on demand for various applications such as targeted drug delivery, microbiome sampling, and tissue biopsy. A mathematical model is developed for mechanism characterization. The opening angle of the capsule is characterized by the magnetic flux density and compared with the mathematical model results. Results show an increase in opening angle as the magnetic field is increased. Additionally, demonstrations of the capsule moving in a custom-built maze as well as inside a stomach phantom are shown. Experiments show successful drug delivery, microbiome sampling, cargo transport, and biopsy using the capsule.

This capsule can be further miniaturized, which will open up the possibility of this capsule being used in other regions of the body. This mechanism can also be leveraged to develop different kinds of microrobots for different microrobotic applications.

Another contribution of this thesis is the development of the biopsy needle capsule. While the previous capsule is useful in taking mucosal biopsy samples, this mechanism can be used to take submucosal biopsy samples, as needle-based biopsy allows penetration to a depth. This capsule also consists of a magnet spring mechanism. A rotating magnetic field is utilized for repeated penetration of a needle inside a tumor to grab a sufficient amount of biopsy sample for better disease diagnosis. The capsule also has a net magnetic moment and hence can be actively moved using a field gradient. This capsule can be used to perform a biopsy in a minimally invasive manner.