Adaptational metamaterials

Artificial material senses and adapts to surroundings

Image credit: University of Missouri

Engineers from the University of Missouri and the University of Chicago are developing a novel material with the capability to respond to its environment without direction from a human.

The artificial material (metamaterial) can sense its environment, independently make a decision based on this information, and perform an action, all without being directed by a human operator. For instance, a delivery drone may evaluate its environment – such as wind direction, wind speed and the presence of wildlife – and automatically change course in order to complete its delivery safely.

The mechanical design of the material incorporates three main functions also shown by materials in nature: sensing, information processing and actuation (movement).

Co-author Professor Guoliang Huang of the University of Missouri said that examples of these functions in nature include the rapid reaction of a Venus fly trap’s jaws to capture insects, chameleons changing their colours to camouflage themselves, and pine cones adjusting their shapes in response to changes in humidity.

“Basically, we are controlling how this material responds to changes in external stimuli found in its surroundings,” he said. “For example, we can apply this material to stealth technology in the aerospace industry by attaching the material to aerospace structures. It can help control and decrease noises coming from the aircraft, such as engine vibrations, which can increase its multifunctional capabilities.”  

The material is at a clear disadvantage compared with computers and complex, multicellular organisms. However, its ability to sense, process information, and respond, can be hugely expanded when the material possesses distributed reservoirs of energy.

The engineers created a material in the form of a thick beam with two degrees of freedom: height of midplane and angle of cross section. A single unit cell within the beam was equipped with three piezoelectric patches; the central patch acts as a sensor (acquiring a voltage proportional to stretching or contraction of its surface) with the two other patches serve as mechanical actuators to elongate or contract in response to an applied voltage.

The engineers incorporated a chip to control or manipulate the processing of information required to perform the requested actions, sending output signals to the two actuating patches. A major advantage of this configuration is that the voltage or power source can be easily housed within the material, which uses electrical power to convert that energy into mechanical energy for movement.

This approach, the Nature Communications paper explains, which is built on symmetries and conservative laws, could be applied to the design of systems such as synthetic biofilaments and membranes with feed-forward control loops.

The next step for the engineers is to implement their idea in a real-world environment.

Sign up to the E&T News e-mail to get great stories like this delivered to your inbox every day.

Recent articles