Detection of Low Sugar Concentration Solution Using Frequency Selective Surface (FSS)

Sugar is important in daily food intake since it is used as food preservative and sweetener. Therefore, is important to analyze the influence of sugar on the spectroscopic properties of the sample. Terahertz spectroscopy is proven to be useful and an efficient method for sugar detection as well as for future food quality industry. However, the lack of detection sensitivity in Terahertz Spectroscopy has prevented it from being used in a widespread spectroscopic analysis technology. In this paper, Frequency Selective Surface (FSS) using the Terahertz Spectroscopy Time Domain Spectrum (THz-TDS) which operates at terahertz frequency range has been demonstrated for application of sugar detection. The FSS is designed with a circle slot structure and has been optimized in line with the molecular resonance of glucose and fructose at different level concentration at 1.98 THz and 1.80 THz, respectively. Transmission magnitude of glucose and sucrose is inversely proportional with the level of sugar concentrations. The realization of the FSS structure is using electron beam lithography and wet etching technique. Results show that the FSS performance for glucose and sucrose reveal fair shifts in measured transmission magnitude from its original in CST by approximately 30%. The use of fabricated FSS with circle structure indicates that the concentration can be improved averagely at 25% for glucose and 13% for sucrose. Thus, it shows that the FSS circle structure combined with THz-TDS has the potential to become an alternative method for food sensing technology in the future.