Abstract
Molecular recognition and discrimination of carbohydrates are important because carbohydrates perform essential roles in most living organisms for energy metabolism and cell-to-cell communication. Nevertheless, it is difficult to identify or distinguish various carbohydrate molecules owing to the lack of a significant distinction in the physical or chemical characteristics. Although there has been considerable effort to develop a sensing platform for individual carbohydrates selectively using chemical receptors or an ensemble array, their detection and discrimination limits have been as high in the millimolar concentration range. Here we show a highly sensitive and selective detection method for the discrimination of carbohydrate molecules using nano-slot-antenna array-based sensing chips which operate in the terahertz (THz) frequency range (0.5–2.5 THz). This THz metamaterial sensing tool recognizes various types of carbohydrate molecules over a wide range of molecular concentrations. Strongly localized and enhanced terahertz transmission by nano-antennas can effectively increase the molecular absorption cross sections, thereby enabling the detection of these molecules even at low concentrations. We verified the performance of nano-antenna sensing chip by both THz spectra and images of transmittance. Screening and identification of various carbohydrates can be applied to test even real market beverages with a high sensitivity and selectivity.
Highlights
We present a nano-slot-antenna array-based THz sensing method supporting the highly accurate measurement of even very small quantities of sugar molecules and the selective identification of different sugar molecules
We demonstrate the detection of sugar levels for real market beverages including diet sodas known to contain a very small amount of artificial sweeteners, which can lead to a new type of non-contact and non-invasive sensing application including a precise sugar monitoring
We measured the THz spectra for several carbohydrate pellets; for D-glucose (a monosaccharide which has the simplest form of a carbohydrate, Fig. 1(a)), fructose (a monosaccharide, Fig. 1(b)), sucrose (a disaccharide which is a combination of the monosaccharides D-glucose and fructose, Fig. 1(c)), and cellulose (a polysaccharide which consists of a linear chain of many linked D-glucose units, Fig. 1(d))
Summary
We present a nano-slot-antenna array-based THz sensing method supporting the highly accurate measurement of even very small quantities of sugar molecules and the selective identification of different sugar molecules. We took notice of several pronounced absorption peak positions in the spectra in Fig. 1(e) (white and black dashed circles) and designed the nano-slot antennas for highly sensitive and selective THz sensing, even after dissolution with a very low concentration of molecules. Our designed nano-slot-antenna array can induce strong THz field localization and a very large field enhancement in transmission[11], thereby effectively increasing the absorption cross section of sugar molecules[12] (Figure S1 in Supplementary Information).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
