A microrobotic platform for precise delivery of drugs within the gastrointestinal tract has been engineered by researchers from California Institute of Technology and Washington University in St. Louis.

Microscopic spheres of magnesium metal and a thin film of medication are coated with thin gold and parylene polymer layers to protect the devices from digestive forces. The microbots are enveloped in microcapsules of Schematic of the microrobotic system in the gastrointestinal tract of a mouse. Source: Z. Wu et al.Schematic of the microrobotic system in the gastrointestinal tract of a mouse. Source: Z. Wu et al.paraffin wax although a circular portion of each sphere remains uncovered, allowing the magnesium to react with digestive fluids and generate bubbles that propel the device forward until it collides with nearby tissue.

A photoacoustic computed tomography (PACT) technique then comes into play to create images of the internal structures of the body. The method can be used to detect tumors in the digestive tract and to track the location of the microrobots. Once the microrobots arrive near a tumor, a high-power continuous-wave near-infrared laser beam is used to activate them. The devices absorb the infrared light and briefly heat up, melting the wax capsule and exposing them to digestive fluids. As the bubble jets activate, the microrobots begin swarming, reaching target areas and releasing medication payloads.

The encapsulated micromotors were demonstrated to survive the erosion of stomach fluid in animal models and permitted propulsion in intestines. PACT noninvasively monitored the migration of the micromotors and visualized their arrival at targeted areas in vivo, as reported in Science Robotics.

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