Scientists make origami-esque sensors
The sensors allow “soft robots” to perform more complicated tasks.
By ZACHARY WHALEN
Scientists from the Viterbi School of Engineering have created a one of a kind strain sensor with an origami-inspired design that allows it to withstand repeated use and take precise measurements.
Strain sensors are used to measure any changes or deformations in what they’re attached to — for example, to track the movements of someone’s hand in VR gaming, or to communicate to a robot how far its hand has moved or its arm has bent. Most current strain sensors are made of a material like rubber or silicone, which does not fare well with repeated use. The new model looks to solve those problems.
Xinghao Huang, the study’s first author and a graduate student studying mechanical engineering, said his background in mechanical engineering led him to research different structures that could be used for the sensor. His research led to origami, which he took inspiration from because of its mutability and ability to maintain its shape.
“We noticed that … you can actually fold and unfold and stretch [origami] to pretty large lengths, and they stay extended,” Huang said. “Also, we noticed that the folding and unfolding [of the origami] was very consistent.”
The team chose a design based on origami’s basic triangle fold, and placed electrodes on either side of the triangle. As the triangle is stretched and compressed, the distance between the electrodes grows and shrinks, which provides the desired data. The distance can be measured both when the sensor is stretched and when it is compressed, an accomplishment other strain sensors have yet to achieve.
“If you compress [the sensor], the folding angle will become smaller and the capacitance will actually increase,” Huang said. “This is a very unique property, because most sensors can only sense large tensile strength, but cannot sense large compressive strength.”
Jonathan Ong, a sophomore majoring in computer engineering and computer science, looked over the study and said he appreciated the scientists’ unique application of origami to engineering.
“It’s really interesting how the origami shape allows it to not deform after a while, like rubber would,” Ong said.
Huang’s next steps in developing this technology include making the sensors temperature resistant while continuing to improve their durability. (Xinghao Huang)
Another of the sensor’s unique attributes is its size: at five-millimeters-by-five-millimeters, it is much more compact than most other sensors, which come in long strips intended for virtual reality. As a result, the sensor has the unique capability of being able to measure very small changes.
One specific application for this technology is in soft robotics. When dealing with rigid robots, it is easy to predict the motion of the robot based on the motion of its joints. But scientists are currently developing soft robots that resemble an elephant’s trunk that wouldn’t have rigid structures, meaning any part of the robot can deform, making it much more difficult to predict its movements.
If Huang’s sensors are arranged on a soft robot, however, they will return very distinct information on how the robot is moving. This information can be used to help scientists gather precise data on the robot’s motions. Eventually, the data may be sent directly back to the robot to give it a sense of itself and its shape to perform more complicated tasks.
The next steps in this research involve making the design more durable and temperature-resistant, as well as developing a way to reconstruct a robot’s entire limb based on data from the strain sensor.
“[The sensor] can tell if the arm is expanding or twisting, but how much is it bent, and can we reconstruct this arm’s shape? The next step is using our sensor data to construct the soft robot’s shape,” Huang said.
Lex Yu, a senior majoring in computer science games, read the study after leading Beyond the Binary through the creation of their own origami. They were impressed by the overall creativity and ingenuity behind Huang’s design.
“It’s a really cool and creative use of technology,” Yu said. “It’s an intersection of art and innovation.”
