Microscopic magnetic probes that change shape in response to their environment may greatly enhance magnetic resonance imaging (MRI). However, producing the probes, which are still experimental and have not yet been used in humans, has required access to a cleanroom and expertise in nanofabrication, limiting their widespread use.
Now, researchers at the National Institute of Standards and Technology (NIST) have taken these shape-shifting probes, known as geometrically encoded magnetic sensors, or GEMS, a step further by unveiling a novel fabrication method that is not only faster and cheaper but eliminates the need for specialized instruments.
The scientists reported their work online Dec. 19 in ACS Sensors.
Instead of building the tiny probes layer by layer in a nanofabrication facility, the team constructed them using a precision master mold. This technique allows researchers to make GEMS in their own laboratories using inexpensive materials and readily available equipment.
A hard silicon master mold is used to create a flexible polymer mold, which is flipped over and filled with hydrogel. The hydrogel is then cured with UV light, producing the cylindrical microparticles.
Credit: S. Kelley/NIST
NIST scientists Gary Zabow and Samuel Oberdick, and their colleagues, focused their efforts on building GEMS shaped like tiny hollow cylinders because that shape can be easily fabricated with a mold. For their master mold, the scientists constructed an array of hollow cylinders made of hard silicon, each only about 100 micrometers in diameter --- about ten times larger than a red blood cell.
The team then demonstrated how researchers ..
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