Activity - Investigate a Nature-inspired Invention: Hook-and-Loop Tape

By Keith Michael Krise

Engineer George de Mestral was walking his dogs in the meadows of the Swiss Alps. When they returned home, he noticed that burr seed pods were stuck on his dogs’ fur! He even found some stuck to his own clothes. De Mestral was curious: Why did the burr seed pods stick to fur and fabric? The answer he found inspired him to invent a special new material … one that you may use every day!

Materials

• Burr seed pod (or do an image search for “burdock seed pod”) 
• Magnifier
• Item that has hook-and-loop tape (Velcro) on it

Procedure

1. Hold a burr seed pod in your hand and feel its texture with your fingers. Then use a magnifier to look closely at the seed pod. 
2. Use a magnifier to look at both sides of the hook-and-loop tape. 
3. Press the hook-and-loop tape together. Pull the pieces apart slightly and use a magnifier to look at the place where the two are being pulled apart. 
4. Next, listen to the sound as you pull the hook and loop sides apart. 
5. Press the hook side against your sock and listen as you pull it off. Press the hook side on a couple of different fabric surfaces and listen as you pull the hooks off. 

• Which makes the loudest sound? 
• What does the hook side stick to the best?
• Why does the hook side stick to the loop side so well? 

How does it work?

When de Mestral looked at the burrs under a magnifying glass, he saw that they had tiny hooks that got caught on the yarns of his clothes and on the dogs’ fur. This observation gave him the inspiration to develop the product that holds shoes on feet, bibs on babies, and rocks in pockets. Velcro, also commonly known as hook-and-loop tape, works so well because the hooks on one side of the tape grab onto some of the many loops on the other side. The hooks are designed to be more rigid and thicker than the loops. When pulled, the flexible loops can detach from the hooks. Some loops are torn in the process, but there are many loops, so this fabric fastener is reusable many times! 

Fun facts about Velcro

• George de Mestral patented his nature-inspired fabric in 1955, calling it Velcro.
• Velcro is a combination of the French words “velours” and “crochet,” which translates to “velvet hook.”
• Astronauts use hook-and-loop tape to secure important scientific equipment (and their dishes) in zero-gravity space. 
• Hook-and-loop tape is made with nylon and polyester. The hooks and loops are nylon and the tape that they are attached to is polyester. 

Keith Michael Krise, Ph.D. is an Associate Professor of Chemistry at Gannon University, in Erie, PA.