Share this
Article<\/p>\n
You are free to share this article under the Attribution 4.0 International license.<\/p>\n
Researchers have drawn inspiration from armadillos to create a protective structure that responds to external threats by curling into a protective ball to protect electronic devices or other payloads.<\/p>\n
The structure is designed to automatically respond when it detects strain and can be tuned to respond to anything from a delicate touch to a significant impact.<\/p>\n
\u201cThere has been a great deal of growth in the fields of soft robotics and flexible electronics, but those devices are often also fragile,\u201d says Yong Zhu, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University.<\/p>\n
\u201cOur goal was to develop a solution that allows these fragile technologies to function but protects them when necessary.\u201d<\/p>\n
\u201cIn its relaxed state, the structure we\u2019ve developed is fairly flexible, but it can be activated to curve into a rigid external structure,\u201d says Jianyu Zhou, first author of the paper and a postdoctoral researcher at NC State.<\/p>\n
\u201cWe could see this technology being used to protect many types of objects\u2014essentially anything it is capable of curving around.\u201d<\/p>\n
The robo-armadillo, which the researchers call the morpho-interlocking protective module (MIPM), consists of three general layers:<\/p>\n
The outer layer, or exoskeleton, consists of a series of segmented, curved scales which are made from a 3D printed resin.
\nThe middle, \u201csensing and actuation\u201d layer, consists of four parts: a liquid-crystal elastomer (LCE), that contracts when heated; a strain sensor made of elastic polymer embedded with silver nanowires; a layer of kapton tape that expands when heated; and then a thin layer of conductive fabric that serves as a \u201cheater\u201d layer.
\nLastly, there is an endoskeleton layer that consists of heavy-duty paper folded into a series of ridges, which hold a row of rigid polymer \u201csegmental scales\u201d in place.<\/p>\n
When the strain sensor detects a touch or impact it signals a control unit, which then sends power to the heater layer. As the heater layer warms up, it causes the LCE layer to contract and the kapton tape layer to expand, causing the entire structure to curve. The end result is that the MIPM structure curls into a protective circle with the exoskeleton facing out.<\/p>\n
\u201cAs the layers curve into a circle, the segmental scales in the MIPM\u2019s endoskeleton lock into each other\u2014creating a robust internal \u2018skeleton\u2019 that contributes to the sturdiness of the structure,\u201d says Zhou.<\/p>\n
In proof-of-concept testing, the researchers found the MIPM works as intended, with the sensor layer detecting increased strain and triggering the transformation into a protective shell. The researchers also found that increasing the number of segmental scales in the endoskeleton significantly improves the structure\u2019s internal rigidity and strength.<\/p>\n
\u201cThrough mechanics-guided design, we established a trade-off between endoskeleton segmentation and structural lightweighting,\u201d says Zhu. \u201cAs an example, 10 segmental scales were capable of withstanding around 10 newtons of force.<\/p>\n
\u201cWe\u2019ve demonstrated a combination of flexibility and mechanical protection that has a lot of potential, and we welcome collaborations from those who are interested in exploring possible applications,\u201d says Zhu.<\/p>\n
\u201cWe\u2019re also very interested in pursuing additional opportunities to advance work on flexible yet protective technologies that draw on nature for inspiration.\u201d<\/p>\n
The paper appears in the journal Science Advances<\/a>.<\/p>\n This work was done with support from the National Science Foundation and the Department of Defense.<\/p>\n