科学60秒:能“识物”的晶片
An inverse opal is a chip of layered glass that includes [--2--]. This mini-labyrinth gets treated with chemicals to modify its inner surfaces. The resulting porous chip then sucks up only liquids that have specific surface tensions. When such a liquid enters the network, it changes the chip's color over a set area. An inverse opal designed to determine if ethanol is [--3--] methanol could thus reveal the letter M if the poison is present.
With this so-called Watermark Ink writing, the chips could also serve as secret code devices. For example, [--4--] a chip with water might make a decoy word like “hello” visible. While exposure to, say, benzene, could expose a secret message, such as “ditch your gas chromatograph.
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