Environmental pollution is a recent social problem with offensive odors, and food contamination is also a new social problem. The odor sensing system for detecting and controlling an offensive odor at an early stage is required. On using simple monitoring gas sensor in environment measurement, gas detecting tubes and semiconductor gas sensors are widely used in general. The quartz crystal microbalance gas sensor mainly detects gases by an electrode and a thin detection film. Therefore, detection films of the sensor depend on the characteristics of the sensing devices using material and processing technology. In addition, the new analyzers using surface plasmon resonance and millimeter-wave technologies (Terahertz radiation) attract attention. The new sensor technologies are expected to detect extremely low concentration from ppm to ppb level with low atmospheric interference.
Plant has various kinds of functions. One of them is a purifying function of gaseous contaminants including carbon dioxide. It is a noticeable function from the standpoint of protection of global environment. Plant can purify not only carbon dioxide but also nitrogen oxide and sulfur oxide, and the chemicals are used as source of energy after broken-down in the plant. And plant puts out a bioelectric potential which changes depending on the environment and growing condition. In this study, the relationship between the potential and purification capability of a plant is examined. Broccoli is adopted as a subjective plant and the experiment is carried out in five kinds of light frequencies including darkness. As a result, the capability becomes higher and the potential also becomes larger in blue light. A positive correlation is recognized in the relationship between the potential and the capability. A specific gaseous chemical could be purified in particular light-frequency by applying the result of this study.
Active oxygen has strong oxidative ability. Therefore, it can be used for surface treatment processing, e.g., cleaning of Liquid Crystal Display (LCD) glass, ashing for resist materials, and sterilization for medical devices. Nevertheless, effects of active oxygen on the surface have not been fully determined, especially in industrial processing. We have been investigating a new method for monitoring active oxygen with the quartz crystal microbalance (QCM) method for practical industrial uses. We review a principle of active oxygen monitoring using QCM and an instance of active oxygen monitoring for plasma treatment processes.
A practical method for measuring methane gas concentration in a mine is developed. The method is based on near infrared absorption technique, where a laser diode (LD) and a light emitting diode (LED) are used as light sources. The resolution better than 0.1% is successfully achieved, and the electricity consumption less than 6W, which is about one tenth of that of other current methods using a halogen-lamp.
Cantilever-based stress sensors can be used for chemical or biochemical sensors. Gas molecules adsorbed or absorbed into a polymer layer which is coated on one side of a cantilever make surface stress at the interface of the film and the cantilever. The stress can be detected as a cantilever bending and a target gas pressure in the ambient of the sensor can be deduced. For high sensitivity, high selectivity and reproducibility of the sensor, we precisely defined the structure and mechanical properties of the absorbent film.
We have been investigating an advanced sterilization system that uses active oxygen species (AOS). We used sterilization equipment that generates AOS from pure oxygen gas by using ultraviolet irradiation and an evacuation system to study the conditions necessary for oxygen injection into the system's chamber. In this way, we optimized the operating conditions for oxygen regulation. Through scanning electron microscope observations, we characterized the mechanism by which AOS inactivated spore-forming bacteria such as Bacillus subtilis.
As the anode material, natural graphite, polymer-coated natural graphite, carbon-coated natural graphite and artificial graphite were employed. In order to examine the effect of solid electrolyte interface (SEI), these samples were exposed to the cycles of charge/discharge. The gas desorption behavior of these samples was investigated by using a technique of thermal desorption spectroscopy. The amount of desorbed gasses significantly increased after a charge/discharge cycle. The increase of the desorbed amount was associated with gas desorption from SEI formed in the first cycle. The amount of desorbed gasses increases with an irreversible capacity in the first charge/discharge cycle. The irreversible capacity of surface-coated graphite and artificial graphite was lower than that of natural graphite. The surface coating resulted in the decrease of the amount of desorbed gasses and irreversible capacity. The atomic composition was measured by auger electron spectroscopy. Carbon, Oxygen, fluorine and phosphorus were observed after a charge/discharge cycle.
Estimating intrinsic electric properties of freestanding BaTiO3 (BTO)/Pt films had been prevented due to leakage current caused by insufficient insulation of the BTO film. This poor insulation is attributed to difficulty in preparation of Pt foils with the flat surface. The present study showed that the flatness of the surface of Pt foils is improved by thinning the carbon (C) buffer layer placed between the Pt layer and Si substrate in Pt/C/Si structure, where the C layer is ablated by annealing in the ambient. By thinning the thickness of the C layer from 166 to 66 nm, the leakage current at 86 kV/cm was drastically improved by more than four orders in magnitude from 1×10−3 A/cm2 to 2×10−8 A/cm2.
We constructed a simple atomic hydrogen source mounted on a conflat flange with an outer diameter of 70 mm (CF70). The source consists of a tungsten filament, a hydrogen gas inlet, and two feedthroughs. The filament is surrounded by a CF70 nipple made of 0.2% beryllium copper alloy and oxygen-free cupper gaskets to reduce the outgassing rate. Using this hydrogen source, we hydrogenated a clean Si(111)-7×7 surface at room temperature. Low energy electron diffraction patterns and Auger electron spectra were measured before and after the hydrogenation.