Derived from life processes, researchers at Aalto University have developed a new material (A next-gen device that lives up to its story) that changes its electrical properties based on past experiences, effectively providing it with a basic form of memory. These flexible materials can play an important role in the next generation of health and environmental sensors, as well as in soft robotics or active surfaces.
Responsive materials have become commonplace in many applications, from sun-darkening glasses to drug delivery systems. But things that exist always react in the same way – their response to change does not depend on their history, nor does it change based on their past.
This is very different from the life cycle, which repeats their behavior based on past situations. “One of the next big challenges in materials science is to create truly intelligent materials from living things. We want to create something that will change its behavior based on its history,” says Bo Peng, a researcher at the Aalto Academy and one of the lead authors of this paper.
The researchers produced micrometer-sized magnetic beads that were stimulated by a magnetic field. When the magnet is turned on, the rocks gather together to form columns. The strength of the magnet affects the shape of the poles, which affects how they conduct electricity.
“With this method, we have used a magnetic stimulus and an electrical response. Interestingly, we found that the electrical conductivity depends on whether the magnetic field changes quickly or slowly. This means that the electrical response depends on the history of the magnetic field. The electrical behavior is also different if the magnetic field is increased or decreased. The response showed bistability, which is a form of early memory. This is done as if it has a magnetic field,” said Peng.
Basic study
The system’s memory also allows it to behave in a manner similar to prior learning. Although learning in living things is very complex, the most important thing in animals is the change in the response of the connections between neurons, called synapses. Depending on how often they are stimulated, the neuron’s synapses will become stronger or easier to activate. This change, known as short-term synaptic plasticity, makes connections between groups of neurons stronger or weaker depending on their recent history.
The researchers were able to accomplish a similar feat with their magnetic beads, although the process was completely different. When they exposed the beads to a fast-moving magnetic field, the material became a better conductor of electricity, while slower sounds made it less effective.
“It is reminiscent of short-term synaptic plasticity,” noted Aalto professor Olli Ikkala. “What we are working on is like a synapse. What we have shown paves the way for the next generation of inspired things that will be based on biological processes of change, memory and learning.
“In the future, there may be other things from algorithms that come from resources that are close to life, although they do not include the complexity of biology. These things will be at the heart of the next generation of soft robots and for health and environmental care,” Ikkala adds.
