title: Broadband 10-300 GHz stimulus-response sensing for chemical and biological entities.
abstract: By illuminating the sample with a broadband 10-300 GHz stimulus and coherently detecting the response, we obtain reflection and transmission spectra of common powdered substances, and compare them as a starting point for distinguishing concealed threats in envelopes and on personnel. Because these samples are irregular and their dielectric properties cannot be modulated, however, the spectral information we obtain is largely qualitative. To show how to gain quantitative information on biological species at micro- and millimetre-wave frequencies, we introduce thermal modulation of a globular protein in solution, and show that changes in single-wavelength microwave reflections coincide with accepted visible absorption spectra, pointing the way towards gaining quantitative chemical and biological spectra from broadband terahertz systems.
authors.affiliation: Department of Electrical & Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706-1691, USA.
authors.forename: Min Ki
authors.initials: MK
authors.lastname: Choi
authors.forename: Kimberly
authors.initials: K
authors.lastname: Taylor
authors.forename: Alan
authors.initials: A
authors.lastname: Bettermann
authors.forename: D W
authors.initials: DW
authors.lastname: van der Weide
mesh_terms: D000818:Animals; D001408:Bacillus anthracis / Q000737:chemistry* / Q000528:radiation effects; D001409:Bacillus cereus / Q000737:chemistry* / Q000528:radiation effects; D023482:Bioterrorism / Q000517:prevention & control; D002417:Cattle; D004574:Electromagnetic Fields; D055590:Electromagnetic Phenomena / Q000295:instrumentation / Q000379:methods*; D046911:Macromolecular Substances; D008872:Microwaves; D010179:Pancreas / Q000201:enzymology; D011208:Powders / Q000737:chemistry / Q000528:radiation effects; D011487:Protein Conformation; D012260:Ribonucleases / Q000032:analysis* / Q000737:chemistry / Q000528:radiation effects; D012542:Scattering, Radiation; D012637:Security Measures; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D046911:Macromolecular Substances; D011208:Powders; D012260:Ribonucleases