Inductively triggered capsule robot for needle-based drug delivery
摘要
Existing capsule robots designed to deliver drugs typically release them into the gastrointestinal lumen, where transport into the tissue depends on passive diffusion across physiological barriers such as the epithelial layer. This limits delivery efficiency. Needle-based delivery can bypass these barriers but requires compact actuation mechanisms that generate multi-newton forces while supporting untethered operation and magnetic steering. Here we present a programmable millimeter-scale capsule robot for needle-based drug delivery enabled by thermally triggered magnetic springs (TTMS). Each TTMS consists of a preloaded magnetic spring and a temperature-responsive locking structure whose trigger temperature can be programmed during fabrication. This enables multi-step sequential actuation using a single global thermal stimulus. The milli-scale capsule robot, featuring multiple TTMS, performs controlled needle ejection, fluid injection, and needle retraction. Contactless triggering is achieved through inductive heating and magnetic steering using an external magnet. Experiments demonstrate programmable thermal response and sufficient force for penetration of soft tissue mimics and ex vivo. Controlled locomotion is demonstrated in complex three-dimensional ex vivo environments. Together, these results establish TTMS as a promising actuation strategy for multifunctional capsule robots and demonstrate a programmable capsule robot capable of inductively triggered needle-based drug delivery.