Disappearing labels could soon tell you when food in your fridge is out of date. The National Taiwan University in Taipei has developed an ink based on anthraquinone β-sulfonate, which fades from red to beige in the presence of oxygen. Varying the thickness of a gas-permeable polyacrylate film on top of a food label allows different sell-by dates to be “programmed” (Food Research International, vol 41, p 653).
Touching frequently used biometric scanners can be unhygienic. So engineers from Malaysia and South Korea have written software that allows a webcam to snap and identify a palm-print without physical contact.…
