Liquid Identification by Hilbert Spectroscopy

October 20, 2009 (HP24).  Today, BBC News featured the liquid identification by Hilbert Spetroscopy using high-T_c Josephson junctions.  The BBC report is based on the paper by Lyatti et al., published in SuST’s ISEC 2009 issue [1].  All the authors are with the Research Center Jülich, Germany.  The online BBC report can be viewed here.  The access to the ISEC 2009 Issue is free until March 31, 2010: click http://www.iop.org/EJ/toc/0953-2048/22/11.

The identification can be attained by measuring the real and imaginary components of dielectric permittivity of the liquid, in the frequency range of main dispersions, which extend from a few GHz to a few THz.  The authors demonstrated total scanning time in the subsecond time between 15 and 300 GHz.  Figure 1 shows the photo of the prototype scanner.  The blue cap belongs to the bottle under test.  The left side box contains the Stirling cryocooler and the junction detector.  On the right is the polychromatic GHz source.  One natural application of the method could be the liquid explosive detection at commercial airports.

Fig. 1.The prototype scanner

 [1]  M. Lyatti, Y. Divin, U. Poppe, K. Urban, “Liquid identification by Hilbert Spectroscopy”, Supercond. Sci. Technol. 22, 114005 (2009).