Magnetic Capsule Robot for Tissue Elasticity Sensing and Tissue Biopsy

Abstract

Monitoring the mechanical properties of soft biological tissues in the gastrointestinal (GI) tract offers a vital route for the early detection of conditions such as intestinal fibrosis, colorectal cancer, and other GI tract diseases. Existing approaches designed to evaluate tissue stiffness often suffer from insufficient accuracy and can impose patient discomfort or the requirement of risky anesthesia for flexible endoscopes or implantable devices. On the other hand, tissue biopsy is essential for diagnosing inflammatory bowel disease (IBD), ulcers and cancer. Existing methods either need anesthesia when using endoscopes or exhibit high risks of obstruction when using capsule robots with needles due to lack of sensory feedback. These limitations underscore the need for advanced minimally invasive capsule devices that can measure tissue elasticity and perform safe and precise biopsy in the hard-to-reach areas such as the small intestine and upper colon. To address these challenges, this thesis reports swallowable capsule devices for palpation-based tissue elasticity sensing and sensor-integrated tissue biopsy. The first device features a remotely actuated palpation mechanism that utilizes an external magnetic field, which relies on a flexible cantilever beam to gently press against soft tissues, with stress and strain recorded by an onboard magnetic sensor and a strain gauge. Real-time communication is enabled by a battery-powered Bluetooth Low Energy (BLE) module, allowing the device to operate autonomously. Additionally, the second capsule device integrates both a sensing unit and a specialized biopsy needle equipped with integrated flexible sensors, thus enabling controlled tissue sampling based on penetration force and displacement feedback. To ensure accurate positioning, a sensor array is deployed for tracking the capsule’s location and orientation during the biopsy procedure. Overall, the magnetically controlled capsule devices show potential for minimally invasive targeted diagnosis functions, to allow earlier interventions for various GI disorders.