This article has no abstract.

View full abstract

Bioelectric potential was investigated to examine the availability of vegetable growth control. The potential is a kind of information transmitted by the vegetable and it varies markedly with one’s physiological phenomenon, light, air contaminant and insect which are external factors. Highly-efficient growth control can be made possible due to clarifying the relationship between the external factors and the potential. Vegetable can be used as a sensor in addition. A hard-leaf cabbage (Ancient specie) was adopted as a subjective plant in this study and the bioelectric potential was measured. The analysis was carried out using the summation of the potential (v_m1) for one minute. The data was input every 0.1 seconds through a difference amplifier. The potential characteristic was investigated as a function of light frequency emitting from a LED panel. In addition, the potential was studied when ethyl alcohol existed and not existed as an air contaminant. As a result, it becomes obvious that the v_m1 is raised when blue and red lights are irradiated. The lights mainly contribute to photosynthesis. The potential increases in the presence of ethyl alcohol which was adopted as a kind of nutrient.

View full abstract

Highly sensitive detection methods for volatile organic compounds (VOCs) are needed in working environment handling the VOCs. The use of a quartz crystal microbalance (QCM) is one such method, and many studies have been carried out on the deposition of metallic, inorganic and organic thin films onto QCM surfaces for use as sensors. In this paper, we report on adsorption properties of fluorocarbon thin films deposited onto the QCM electrode by an r.f. sputtering and spin coating for low molecular weight VOCs such as aliphatic alcohols and acetone. Adsorption mass of these VOC molecules in the fluorocarbon thin film deposited by the r.f. sputtering were much higher than that in the thin film deposited by the spin coating. It is known that molecular structures of fluorocarbon thin films sputtered with a Poly(tetrafluoroethylene) (PTFE) target were quite different from pristine PTFE. It is considered that this is one of reasons why the adsorption mass in the thin film deposited by the r.f. sputtering was higher than that in the thin film deposited by the spin coating.

View full abstract

Recently, there is a problem of the steady supply of food therefore plant factory has been establishing and takes off in world wide countries. In the plant factory, the growing environment can be controlled and the crop can also be controlled. The products are growing in an enclosed environment, therefore agricultural chemicals has no use. Secure and safe food producing system can be constructed. However, efficient production formula for the plant (for example vegetable) is not defined well. It is an effective way to control the growing environmental factors using physiology information which are directly obtained from the vegetable. The chlorophyll fluorescence is used as evaluation of plant condition. It is necessary to clarify the bioelectric potential in the growth condition of the plant. In this study, we examined the relationship between the chlorophyll fluorescence and the plant bioelectric potential in bad condition. The plant in spraying chemical herbicides was assumed as the condition. In future, plant physiological function and environmental response can be understood by directly monitoring the bioelectric potential.

View full abstract

We focused on measurement of the bioelectric potential as a method of evaluating plant activities and supporting effective cultivation. In this study, we researched on the bioelectric potential response due to photochemical reaction and carbon-fixation reaction in the process of photosynthesis. At first, we measured the bioelectric potential when illumination started and stopped, under N₂ gas condition for suppressing carbon-fixation reaction and respiration. In the result, amplitude of the potential response related to illumination intensity and wave length. We considered that the amplitude of potential response in N₂ condition indicated activity of photochemical reaction. Based on this result, we investigated the potential response in room air condition. If carbon-fixation reaction was deactivated by long dark period, significant potential decrease was observed when illumination started. In contrast, if carbon-fixation reaction kept active during short dark period, potential decrease was slight or none regardless of photosynthetic rate. Therefore, we considered that this potential decrease related to activation of carbon-fixation reaction. Next, we researched on relationship between plant activities and the potential response when illumination stopped. The result shows that amplitude of the response related to illumination intensity and respiration rate. We conclude that plant activities such as photosynthesis can be evaluated in more detail by measurement of the bioelectric potential with applying this study.

View full abstract

Recently, development of taste sensor is furthered for quality control of foods. In this study, we developed taste sensor with stearic acid LB films for measurement of high-intensity sweetener taste. We measured several high-intensity sweeteners with the number of layers of stearic acid LB films as 10 and 20 layers. And we also measured mixed high-intensity sweeteners. The result showed that the stearic acid LB films taste sensor was used to detect glucose and high-intensity sweeteners at a threshold level of taste. Stearic acid LB films sensor detects different response by mixed ratio of high-intensity sweeteners. In addition, we compared difference of sensor responses by three kind of storing conditions (vacuum vessel, KCl solution and the air storing). The result showed that the structure of stearic acid LB films is easily affected by moisture in storage environment. This study indicated that the modification of stearic acid LB film layers and materials makes it possible to develop high sensitivity and selectivity taste sensor for sweeteners.

View full abstract

We propose a simple and environment-friendly fabrication method named “Inkjet liftoff method” for preparing film-based electrodes. Metal electrodes for chemical sensors have been fabricated on a transparency film by a kind of liftoff method using an inkjet printer. The whole fabrication process comprises of the steps of: (Step 1) inkjet-printing of the reversal pattern of the electrode on a transparency film, (Step 2) drying of ink, (Step 3) vapor-depositing of metal layers, (Step 4) and removal of the ink together with the upper metal layers of it. The advantage of this method is that the final liftoff step is carried out by simply exposing film to water. To demonstrate the usefulness of this method, we fabricated a glucose sensor.

View full abstract