Brains On! Science podcast for kids · Brains On Universe

How do stickers stick?

January 27, 2026·25 min·2 clips

Zoom in to see how sticky molecules flow like liquid into paper's bumps to make stickers stick.

This episode of Brains On! explores the science behind how stickers work, hosted by Molly Bloom and kid co-host Amira from Indianapolis. They are joined by sticker scientist Phil Messersmith from UC Berkeley, who researches advanced adhesives. The episode uses a fictional "ZoomRay" tool to visually explain adhesive molecules at a microscopic level. Stickers are classified as pressure-sensitive adhesives, requiring physical pressure to make their long, flexible molecules flow into a surface's microscopic bumps and dips. Most surfaces, like paper, are surprisingly rough when magnified, and the adhesive molecules lock into these imperfections. Unlike wet glues that dry or hot glues that cool, these adhesives maintain a balance between liquid-like flow and solid-like stability. Scratch-and-sniff stickers work by embedding tiny smell-filled capsules into the paper that break open when scratched. The show notes that juice boxes are made of 5-10 material layers held together by adhesives. Phil Messersmith's lab is developing fully recyclable stickers and medical adhesives that can act as internal bandages to seal intestinal holes. A surprising insight is that the key to a sticker's hold is the act of pressing it, which forces the adhesive deeper into a surface's texture. The episode reveals that common items like juice boxes and price tags are everyday applications of sticker technology. Listeners learn that medical adhesives must be waterproof and biocompatible to function inside the human body. The fictional "Creature Creeper" and "Sneakachu" stickers illustrate the fun, collectible side of stickers. A mystery sound segment features a homemade volcano created with baking soda and vinegar. The hosts also solicit listener ideas for naming their generation, with Amira suggesting "Coronial." The tone is educational, playful, and highly conversational, designed to make complex scientific concepts accessible and entertaining for young audiences. It incorporates imaginative sound effects, humorous skits with characters like Sanden and Bob, and interactive segments like the mystery sound and mailbag. Young science enthusiasts and curious kids who enjoy hands-on experiments and everyday mysteries would love this episode. Listeners seeking a deep, technical scientific lecture or those annoyed by whimsical sound effects and fictionalized explanations might prefer to skip it.

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