Moving gears towards chemical devices


IMAGE: Animation from simulation showing spatio-temporal control of rotors through inhibition reaction. A rotor with a GOx (magenta) cover lies to the left of the chamber, and a CAT-covered rotor (green) lies on the … view more

Credit: A. Laskar

PITTSBURGH (December 18, 2020) … The gear is one of the oldest mechanical devices in human history1 and has led to devices ranging from early irrigation systems and clocks, to modern engines and engines- artificial. For the first time, researchers at the University of Pittsburgh Swanson School of Engineering have used a catalytic regenerator that causes a bilateral sheet, with a chemical coating, to “morph” without force into a three-piece gear. side that does a stable job.

The findings highlight the potential of developing chemically driven devices that do not rely on external power, but only need to add reactors to the surrounding solution. Published today in the journal Cell Press Issue (DOI: 10.1016 / j.matt.2020.11.04), the research was developed by Anna C. Balazs, Distinguished Professor of Chemical and Petroleum Engineering and Chair of Engineering John A. Swanson. The lead author is Abhrajit Laskar and co-author is Oleg E. Shklyaev, both postdoctoral fellows.

“Gears help give machines mechanical life; however, they require some form of external power, such as steam or electricity, to perform an action. This limits the capacity of machines in time. future to work in resourceless or remote environments, “Balazs explains. “Abhrajit computational modeling has shown that chemo-mechanical transmission (conversion of chemical energy to motion) at active leaves provides a new way to reproduce gear behavior in environments without access to traditional power sources.”

In the symbols, catapults are placed at different locations on a two-dimensional sheet resembling a wheeled wheel, with heavier knots on the circumference of the leaf. The flexible leaf, about a millimeter long, is then placed in a microchamber filled with water. A reactant is added to the chamber which activates the catalysts on the horizontal “wheel”, thus causing the liquid to flow without spores. The internal water flow drives the lighter sections of the sheet to pop up, creating an active rotor that captures the flow and turns.

“What is very special about this research is the connection of deformation and movement to change the shape of the object to create movement,” Laskar says. “Deformation of the object is crucial; we see in nature that organisms use chemical energy to change their shape and movement. For our chemical sheet to move, it also needs to morph spontaneously in a new shape, which allows it to capture the fluid flow and perform its function. “

Furthermore, Laskar and Shklyaev found that not all gear parts had to be chemically active for a shift to occur; indeed, inconsistency is essential to the creation of movement. Determining the design rules of the setting, Laskar and Shklyaev could direct the rotation clockwise or counterclockwise. This “program” added control of independent rotors moving in series or in stop effect, with active and passive gear systems. This more complex action is controlled by the internal structure of the paws, and their position within the fluid field.

“Since gear is a key part of any machine, you have to start with the basics, and what Abhrajit has created is like an internal combustion engine at millimeter scale,” Shklyaev says. this is power for your car, it has the ability to build basic machines for moving small chemical and soft robots. ”

In the future, Balazs will explore how multi-gear spatial organization could lead to increased functionality and potentially design a system that seems to have done so. -decisions.

“The more remote a machine is from human control, the more you need the machine itself to provide control to perform a specific function,” Balazs said. “The chemo-mechanical nature of our machines allows thus occurring without an external power source. “

These self-morphing gears are the latest evolution of chemo-mechanical processes developed by Balazs, Laskar, and Shklyaev. Other advances include the creation of crab-like sheets that mimic feeding, flying and fighting responses; and “flying carpet-like” sheets that fold, shake and creep.


1M.JT Lewis, Equipping in the Old World, Make an effort, Volume 17, Issue 3, 1993, Pages 110-115, ISSN 0160-9327.


This work was supported by the Department of Energy under grant number DE-FG02-90ER45438 and in part by the University of Pittsburgh Research Computing Center through the facilities provided.

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