In the alcoholic beverage industry, expressing “flavor” of sake in an easy-to-understand manner is one of the important issues. So far, we have been conducting equipment analyses using taste sensors and sensory evaluation when people actually drink sake in order to easily understand the “taste” of sake felt by the tongue. By combining them statistically, we have developed the "Sake Flavor Chart". However, the map does not include data on the “scent” of sake. The scent of sake is composed of various ingredients such as banana and apple-like scent called “Ginjo” scent, aged scent, and aldehyde odor, and is a very important factor in expressing the "flavor" of sake. The purpose of this study is to improve the accuracy of the existing sake taste map by comprehensively analyzing the "flavor" of sake using a taste sensor and GC-MS. In this research, “Sake Flavor Chart” becomes a tool that can express not only the “taste” but also the “scent” of sake in an objective and easy-to-understand manner by approaching the flavor of sake from more diverse perspectives than before.
A solid-state micro NOX sensor was tried to make using a solid-electrolyte Li1.5Al0.5Ti1.5(PO4)3 (LATP) thin-film as an impedance transducer and a perovskite-type oxide thin-film as a receptor, respectively. The LATP and perovskite-type La0.8K0.2MnO3 oxide thin-films were prepared by wet-chemical methods at 650-800°C. The La0.8K0.2MnO3/LATP thin-film device could work as a good impedancemetric NO2 sensor at 300-500°C.
In this study, to detect amine gases such as ammonia, a kind of biological gas, with high sensitivity, we fabricated a device that combines an inverse opal photonic crystal (IOPC) and 2-(4-oxo-3,4-dihydroquinazolin-2-yl)phenyl acetate (HPQ-Ac), a precursor of the aggregation-induced emission luminogen. IOPC silica structures (200IOPC, 350IOPC, 500IOPC) with SiO2 were respectively obtained after calcination with 200, 350, and 500 nm polystyrene (PS) nanoparticles used as templates and tetraethyl orthosilicate (TEOS) formed by self-assembly on a slide glass. Furthermore, mesopore-introduced IOPC (50 nm-350IOPC) was prepared by mixing 350 nm and 50 nm PS particles in TEOS solution. Each IOPC was infiltrated with HPQ-Ac, reacted with ammonia, and the rate of change in emission intensity owing to fluorescence was examined. The highest response was obtained for 350IOPC infiltrated with HPQ-Ac among the three IOPCs without mesopores. The 50 nm-350IOPC had higher sensitivity than 350IOPC and was found to be able to detect 50 ppb ammonia gas.
Stochastic resonance have been known as a phenomenon which can enhance weak input signals added nonlinear systems with the presence of noise. In this paper, we considered the summing network as a multi-input system configuration, which occur the optimal stochastic resonance without tuning of system parameters. This configuration can be expected to improve the detection sensitivity of the input signals measured simultaneously by integrating multiple sensors, but the number of sensors cannot be increased indefinitely depending on the problem. Then we propose a method to reduce the number of elements required for the configuration by using oversampling. It was shown that the proposed configuration could improve the input-output correlation while reducing the number of nonlinear elements.
The human body emits various volatile molecules, depending on a person's genetics, stress, disease and so on. The volatile organic compounds (VOCs) can be found in human transpiration, breath and transdermal gas emanated from skin. In this review, a biochemical gas sensor “bio-sniffer” and a gas imaging system “sniff-cam” for monitoring of VOCs such as acetone, ethanol and acetaldehyde were presented. Firstly, a high-sensitive acetone biochemical gas sensor was demonstrated and measure exhaled breath acetone concentration, and assess lipid metabolism based on breath acetone analysis. Secondly, a fluorometric imaging system for ethanol vapor released from human breath and palm skin was presented. This imaging system measures ethanol vapor concentrations as intensities of fluorescence through an enzymatic reaction. These biochemical gas sensors and imaging system of VOCs showed a rapidly and accurately responses and measurement, which could lead an analysis to metabolism function and non-invasive screening at real time in the near future.