Gadgets to Go

摘要

Keith schacht flicks a cigarette lighter and holds the flame to a business card. He smiles when white letters and circles appear on the paper. The cards coating is embedded with thousands of microscopic hollow plastic balls that expand when heated. These "microspheres" were made by a division of Akzo Nobel in the Netherlands. The business card idea makes Schacht wonder whether the tiny balls might be added to a birthday card to reveal a surprise message when the card is held over birthday-cake candles.