Name that whiff

 作者:密袭系     |      日期:2019-03-08 04:16:04
Chemicals ranging from nerve gas to emissions from mouldy food can now be sniffed out by a palm-sized vapour detector made by by Orlando, Florida-based Sawtek. The VaporLab system contains four piezoelectric crystals, each of which is coated with a different polymer that absorbs target vapours. Absorption changes the crystal’s resonant frequency,