Custom-designed silicon microparticles that both assemble and disassemble themselves could form the basis for creating artificial muscles, as well as reconfigurable computer systems.
A first-of-its-kind demonstration led by researchers at Duke University and North Carolina State University showed that the particles could be repeatedly steered into various configurations while suspended in water.
Ugonna Ohiri, a recently graduated electrical engineering doctoral student from Duke and first author of a paper on the research, referred to the work as creating a “reconfigurable silicon toolbox” by engineering and encoding multiple dynamic resources in different microparticles. "By providing a means of controllably assembling and disassembling these particles,” Ohiri said, “we're bringing a new tool to the field of active matter."
What’s unique about the research is its exploration of a wide range of custom shapes, sizes and coatings relevant to the microfabrication and nanofabrication industries. Using silicon, moreover, presents the opportunity to physically realize electronic devices that can self-assemble and self-disassemble on demand.
"Most previous work performed using self-assembling particles has been done with shapes such as spheres and other off-the-shelf materials," said Nan Jokerst, an electrical and computer engineering professor at Duke. "Now that we can customize whatever arbitrary shapes, electrical characteristics and patterned coatings we want with silicon, a whole new world is opening up."
By observing how a variety of fabricated particles responded to different magnitudes and frequencies of electrical fields, the researchers were able to create custom particles to exhibit desired behaviors: moving through water, synchronizing their motions, reversibly assembling and disassembling.
The rectangular particles, which measure 10 x 20 x 3.5 microns, are fabricated using silicon-on-insulator (SOI) technology – the same process that produces integrated circuits. As a result, millions of identical particles could be produced at a time.
Ultimately, said Jokerst, the goal would be to make silicon computational systems that assemble, disassemble and then reassemble in a different format.
"This work is just a small snapshot of the tools we have to control particle dynamics," Ohiri added. "We haven't even scratched the surface of all of the behaviors that we can engineer, but we hope that this multidisciplinary study can pioneer future studies to design artificial active materials."