Hawkes is working with a team of engineers to develop controllable, reusable adhesive materials that, like gecko toes, can form a strong bond with smooth surfaces but also release with minimal effort. In previous research, the performance of gecko-inspired adhesives decreased as the application increased in size. Hawkes and his co-workers have developed a device that shares large loads evenly across every patch of the adhesive, making it possible for a person to climb a glass wall, as shown in the video below.
As described in a paper published in the Journal of the Royal Society Interface, the adhesive consists of polydimethylsiloxane (PDMS) slanted microwedges that are approximately 100 μm tall, which adhere well to glass and can be repositioned many times without degradation. "While other dry adhesive materials produce larger adhesive stresses, PDMS microwedges are especially suitable for climbing because they exhibit controllable adhesion that can be effectively switched on or off in a fraction of a second by applying a shear stress," write the authors. "Therefore, a climber can attach PDMS microwedges simply by transferring weight to the adhesive, and can detach by removing the weight, requiring nearly zero added effort."
Climbing a glass wall using this device is "a lot of fun, but also a little weird, because it doesn't feel like you should be gripping glass," Hawkes said in a press release published by the Stanford Report. "You keep expecting to slip off, and when you don't, it surprises you. It's pretty exhilarating."
The current version of the device can support about 200 pounds, Hawkes said, but, theoretically, increasing its size by 10 times would allow it to carry almost 2000 pounds.
