Machine Design

Smart pills

Self-assembling cube-shaped perforated containers no larger than a dust speck could precisely deliver medications in the body, say researchers at Johns Hopkins.

The technology could lead to "smart pills" that send a collection of the containers to the site of an injury or illness. The microcontainers could someday incorporate electronic components that would let the cubes act as biosensors or release medication in response to a remote RF signal.

Techniques used to build microchips produce a flat pattern of six squares resembling a cross. Each copper or nickel square has etched into it small openings which eventually let medicine or therapeutic cells pass through. Metallic solder forms hinges along the edges between adjoining squares. Briefly heating the squares melts the metallic hinges. High surface tension in the liquified solder pulls each pair of adjoining squares together to form a perforated cube. Upon cooling, the solder solidifies and the containers remain cube shaped. A thin layer of gold then coats the cubes to help prevent toxicity problems in the body.

Next, micropipettes insert into the cubes a suspension containing microbeads that are commonly used in cell therapy. Agitating the cubes releases the beads. The researchers also inserted human cells similar to those used in cell therapy. A positive stain test verified the cells remained vital in the microcontainers and could easily be released. Researchers also used MRI to locate and track the metallic cubes as they moved through a sealed microscopic S-shaped fluid channel, simulating movement in the body. Some of the cubes are magnetic so it should be possible to guide them directly to a site of interest.

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