Nanofiber-based biodegradable millirobot with controllable anchoring and adaptive stepwise release functions

A millirobot that can work in the alimentary tract is of great interest for future biomedical treatments, but challenges remain for the robot in the integration of multiple drugs, effective locomotion under the harsh in-body environment, controllable anchoring on the desired area, and adaptive stepwise release. Here, we report a nanofiber-based biodegradable millirobot, named Fibot, fabricated by integrating magnetic-assisted molding and electrospin-assisted assembling. By adjusting the material components of Fibot during fabrication, we can program the adaptive release of different drugs responding to variations in acidic physiological concentrations. Moreover, the multi-legged design gives it an effective locomotive ability even in the harsh in-body environment. We demonstrate locomotion abilities in the GI tract, desired-region anchoring, and multiple-drug stepwise release in a rabbit model. This research will shed new light on millirobot development and promote the realization of untethered, biodegradable, functional, and environmental adaptive devices to be implemented in various biomedical applications.