Novel extrusion system for the encapsulation of drug releasing bio-medical micro-robots

This paper examines the design and testing of a novel extrusion system for the biocompatible coating of drug delivering micro-robots. The encapsulation system creates monodisperse droplets of sodium alginate containing the micro-robots within a coaxial laminar flow of a continuous oil phase. The extrusion process allows the experimenter to control the size of the drug carrying droplets which have been subsequently tested as vehicles to deliver a model drug (Horseradish peroxidase). Comparison with other coating techniques such as dip-coating shows significant increase in the drug storing capacity. A demonstration of the use of ultrasound as a possible trigger of the drug release has also been presented. The significant increase in the observed drug release rate shows enhancement over previously tested passive diffusion and magnetic modulation methods. Together, these two aspects of micro-robotic drug delivery concept introduce a new approach to drug-delivering micro-robots with large drug-storage capacity, ability to propel the robots using magnetic forces, and trigger the drug-release by remote application of ultrasonic stimulation.