In what may seem like more magic than engineering, researchers at University of Pennsylvania's School of Engineering and Applied Science have produced objects without a brain or a nervous system that are capable of making sophisticated decisions, a feature they call "embodied logic." Best of all, the objects are 3D printed!
Inspired by the Venus flytrap
The engineers took inspiration from the brainless Venus flytrap's ability to either snap on potential prey or reject that which it can't eat.
Then, by toying with "stimuli-responsive materials and geometric principles," the team of researchers designed structures able to decide on appropriate responses to environmental cues using "physical and chemical makeup alone."
To achieve this the engineers used bistable structures due to the fact that they can hold one of two configurations indefinitely.
"Bistability is determined by geometry, whereas responsiveness comes out of the material's chemical properties," said Jordan Raney, assistant professor in Penn Engineering's Department of Mechanical Engineering and Applied Mechanics.
"Our approach uses multi-material 3D printing to bridge across these separate fields so that we can harness material responsiveness to change our structures' geometric parameters in just the right ways."
What this means is that the team's 3D printed objects can take on several configurations in response to the pre-determined environmental phenomenon.
Without a brain, a nervous system, any motors or batteries, the objects respond to changes in environmental stimuli such as humidity.
Toying with several factors
"This bistable behavior depends almost entirely on the angle of the beams and the ratio between their width and length," Raney explained.
"Compressing the lattice stores elastic energy in the material. If we could controllably use the environment to alter the geometry of the beams, the structure would stop being bistable and would necessarily release its stored strain energy. You'd have an actuator that doesn't need electronics to determine if and when actuation should occur."
The team also toyed with the "beams' starting length/width ratio." This is where the 3D-printing technique was key because it allowed for the incorporation of different materials in the same print giving the resulting objects multiple shape-changing responses including sequential ones.
"For example," Yijie Jiang, a postdoctoral researcher in Raney's lab, said, "we demonstrated sequential logic by designing a box that, after exposure to a suitable solvent, can autonomously open and then close after a predefined time. We also designed an artificial Venus flytrap that can close only if a mechanical load is applied within a designated time interval and a box that only opens if both oil and water are present."
The work has potential applications in microfluidics or even in providing sensors in isolated harsh environments perhaps possibly even on other planets.
Because the materials do not require batteries or any human support or intervention, these sensors could remain dormant for years and only be activated by the right environmental cues.
We wouldn't be surprised if a NASA collaboration was soon achieved. In the meantime, the open access study outlining the work is published in the journal Nature Communications.