February 21, 2024

Typically, tape either has a strong hold or is easy to remove. However, drawing inspiration from the ancient technique of kirigami, scientists have now devised a way to combine these two properties of existing types of tape.

Kirigami is a Japanese art form in which slits are strategically cut into flat sheets of paper so that the paper takes on a three-dimensional shape when pulled from the ends. In recent years, we’ve seen it used in innovations such as robotic grippers, non-slip shoe clips, and snake robots.

For this tape, a Virginia Tech team led by Assoc. Professor Michael Bartlett cut a row of U-shaped cuts in commercially available adhesive tape, which he then applied to different surfaces.

Then, when the scientists tried to peel the tape off by pulling it in one direction (up from the bottom of the U), it showed a bond 60 times stronger than its unaltered counterpart. However, when it is peeled in the opposite direction, it comes off easily. Why is this so?

“The engineered cut can force the adhesive separation path back at specific locations, what we call reverse crack propagation, making the adhesive very strong,” Bartlett said. “But by peeling in the opposite direction, it always moves forward, making it easy to remove. It’s very unusual behavior, but it’s very useful for making strong and peelable adhesives.”

Tape is difficult to peel off when pulled "against the grain"
Tape is difficult to peel off when pulled “in the opposite direction”

Alex Parrish, Virginia Tech

In laboratory tests, a brick was repeatedly dropped onto a cardboard box, the top of which was sealed with either plain or decoupage tape. The former failed after just two drops — causing the box to collapse — while the former lasted at least five drops. Importantly, we also found that different shapes and sizes of slits worked better for different types of tape.

In addition to use in secure and easy-to-open boxes, other possible applications for the technology include robotic grippers, wearable health monitoring devices, and products optimized for easy recycling.

“It’s very common to make adhesive bonds stronger but harder to remove,” Bartlett said. “It’s also common to make those bonds less strong but easier to remove. The challenge is to make them stronger and Still easy to remove, and that’s what we’ve achieved.”

A paper on the research was recently published in the journal natural material. The video below demonstrates the technique.

Stronger tapes engineered through dicing technology

source: Virginia Tech