Using a phenomenon known as contingency behavior on a microscopic scale, MIT engineers I engineered simple microparticles that can generate complex behaviours, such as a colony of ants or other social insects. Details are described in the magazine Nature Communications.
In addition to being physically intriguing, this behavior can also be translated into an onboard oscillating electrical signal that can be very robust to the autonomy of microbots. There are many electrical components that require such an oscillating input.Jingfan Yang, a doctoral student at the Massachusetts Institute of Technology and one of the study’s authors
The particles perform a simple chemical reaction that allows them to interact with each other by forming and rupturing small gas bubbles. Under the right conditions, these interactions create an oscillator that behaves like a ticking clock that pulses at intervals of a few seconds.
We try to find very simple rules or features that can be coded into relatively simple little bots so that they can perform very complex tasks together.the professor. Michael Strano of the Massachusetts Institute of Technology
Demonstrations of emerging behavior can be seen throughout the natural world, where colonies of insects such as ants and bees perform feats that no single member of the group would be able to accomplish.
Ants have small brains and perform very simple cognitive tasks, but collectively they can do amazing things. They can search for food and build complex tunnel structures. Physicists and engineers like me want to understand these principles because they mean we can create small things that collectively perform complex tasks.the professor. Michael Strano
MIT researchers have designed molecules that can generate very low frequency rhythmic motions (oscillations). Until now, creating micro-oscillators has involved the involvement of complex electronics that are expensive and difficult to design, or require specialized materials.
The simple particles designed for this study were tiny discs up to 100 microns in diameter made of a polymer called SU-8. They have a platinum patch that can catalyze the breakdown of hydrogen peroxide into water and oxygen. When the molecules are placed on a drop of hydrogen peroxide on a flat surface, they tend to travel to the top of the drop. At this air-liquid interface, they interact with other particles present.
The particle itself remains stationary and does nothing interesting, but thanks to their collective action, they can do something very amazing and useful, which is difficult to achieve on a microscopic scale.Jingfan Yang
Two particles can create a reliable oscillator, but as more particles are added, the rhythm becomes turbulent. However, if they add a particle slightly different from the others, it can act as a “leader” that reorganizes the remaining particles into a rhythmic oscillator.
This lead particle is the same size as the other particles, but has a slightly larger platinum patch, which allows it to form a larger oxygen bubble. This allows the particle to travel to the center of the group, where it coordinates the oscillations of all the other particles. Using this approach, the researchers found that they could create oscillators with at least 11 particles. Depending on the number of particles, such an oscillator pulses at a frequency of about 0.1-0.3 Hz, which is the arrangement of low-frequency oscillators that govern biological functions such as walking and heartbeat.
It has also been shown that regular beating of these particles can be used to generate an oscillating electric current. To this end, they replaced the platinum catalyst with a fuel cell made of platinum, ruthenium or gold. The mechanical oscillation of the resistance molecules rhythmically changes from one end of the fuel cell to the other, converting the voltage generated by the fuel cell into an oscillating current.
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