Researchers at the University of Lille developed a device that enables ionization and MS analysis of proteins, lipids and metabolites from the outermost few microns of skin or other tissues. The device, called the SpiderMass, works by selectively exciting water in the tissue with a pulsed laser. The ions are aspirated and transferred to a mass spectrometer for analysis. Ionization leaves a white trail of dehydrated skin, but the traces disappear within a few minutes. Volunteers reported just a slight tingling sensation.