If you see a grain of sand rolling uphill, you might be forgiven for thinking that you are looking at a grain of sand. christopher nolan movies. But scientists recently discovered a way to return sand-like material to slopes without rewinding time.
researcher Engineer from Lehigh University, USAThese are particles called micro rollers, which are coated with fine particles of polymethyl methacrylate plastic. iron oxide.
Activating a rotating magnetic field near an inclined pile of particles creates torsional forces and torque There is one individual microlar. Coupled with fluctuations in the gravitational forces between the particles, the “sand” was able to run up slopes on its own, even defying gravity and overcoming obstacles.
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“Using equations that describe the flow of particulate matter, we were able to conclusively show that these particles do indeed move like particulate matter, except that they are flowing uphill. Ta.” To tell chemical and biomolecular engineer James Gilchrist;
The behavior was so unexpected that researchers had to come up with a new term to describe it. Upward flow is called a negative angle of repose and is caused by a negative angle of repose. Coefficient of friction It actually speeds up the movement instead of slowing it down as it usually does.
When a magnetic torque is applied to these microrollers, they rotate around their axes, causing the particles to temporarily gather and move in unison. This rolling and subsequent agglomeration allows the particles to climb up the slope.
more powerful magnetic field The researchers report that increased cohesion means the particles gain more traction and move faster. Collective effects are impossible if the grains are simply acting independently.
Although research is still in its infancy, there are many potential applications. Consider that scientists can control how substances are mixed or separated. This approach could also be used in microrobotics and possibly drug delivery.
That remains to be seen, but the team has some solid ideas about what to work on next with their discovery, and work on building tiny staircases that this strangely migrating grain can climb is It’s already started.
“While this first paper focuses solely on how materials flow uphill, several upcoming papers will look at applications, and part of that exploration will include To answer the question: Can a roller climb an obstacle? To tell Gilchrist. “And the answer is yes.”
“We study these particles thoroughly, experimenting with different rotational speeds and different amounts of magnetic force to better understand their collective motion.”
This study nature communications.