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.

Analysis and design of rectangular microstrip antenna on two-layer substrate materials at terahertz frequency

“…terahertz regime, which is one of the least explored and most promising region of the electromagnetic spectrum for a growing range of applications [1,2] such as sensing, imaging and wireless communications, detecting explosive [2] or bio-weapons [3][4][5][6][7] and spectroscopic imaging for biomedical applications could become significant. The potential challenges to terahertz technology include making compact and robust sources and detectors, enabling turnkey application in laboratories of the non-specialist and enhancing the management of terahertz lights though the antennas for both far-field and near-field.…”

Ultra-sensitive detection of protein thermal unfolding and refolding using near-zone microwaves

“…5). A fixed number of peaks (7)(8)(9)(10)(11) were used to fit all return-loss scans in an unfolding/refolding series.…”

“…This method not only allows measurement of proteins and other biomolecules in their "natural" aqueous state, but also permits correlation and comparison with results obtained using an established spectroscopic method. Variations of this technique have been previously described in the literature [11]- [13].…”

Analysis of terahertz spectral images of explosives and bioagents using trained neural networks

“…Consider an envelope containing a metal coin, and numerous blotches of organic material including two starch, two flour, and two bacillus subtillus (an anthrax simulant). An examination of published THz transmission spectra for these materials (1,8) resulted in the training set shown in Table 1. The minimum and maximum values of 0 and 10 correspond to total reflection and total transmission, respectively.…”