Study on water quality detection of hydroponic plants using the method of measuring refractive index

• Main Authors: Jyh-Shyan Chiu, 邱智賢
• Other Authors: Wen-June Wang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/4759va

博士 === 國立中央大學 === 電機工程學系 === 106 === There are many plant studies in the world. In the countries of using considerable research funds to develop related technology, the main factor is focused on automated management. But this paper proposed "Study on water quality detection of hydroponic plants using the method of measuring refractive index ", don’t need to add chemicals as a catalyst or use spectrum instrument to measure, have advantages of immediate and inexpensive measurement. The study conducted on light emitting diode plant factories have mostly adopted hydroponics for convenient nutrient management and pest and disease prevention. In particular, in nutrient management, liquid electrolytes can be measured to determine the aqueous nutrient concentrations and absorption rates as well as electrical conductivity (EC) and pH variations. Precisely controlling the aqueous nutrient contents is crucial to large-scale healthy plant production. However, in most of the current conductivity measurements, electrodes are adapted for determining the nutrient additive concentrations. This approach can be problematic in some cases, such as low electrode sensitivity, which results in nutrient overdose, specifically in nonconductive additives, and hinders plant growth. Therefore, this paper proposes an optical method for measuring the aqueous nutrient contents. In this method, the high sensitivity of common-path heterodyne interferometry is incorporated into aqueous measurements to prevent errors caused by interfering impurities on the electrodes and improve measurement and analytical accuracy. The sensitivity of the sensor used in EC measurements can reach 2300°/mS·cm-1. The method has some merits, e.g., a simple optical setup, high stability etc., high measurement accuracy, high resolution, rapid measurement, and easy operation. In addition, its feasibility is demonstrated. Undergoing the advanced study, it would be found that there were many questions if the two long sides were coated thin-film metals. One was that the measured signal was very weak because of much attenuation. Besides, the measured phase difference could be more than 360 degrees. It would result in the measurement misjudgment. Therefore, how to develop a high sensitivity and high resolution photoelectric biochemical sensor becomes a very important development goal. This proposes a photoelectric biosensor exhibiting instantaneous and simple measurement properties. On the basis of surface plasmon resonance principles, the proposed biosensor capitalizes on the adhesion activity between test fluids and metal films. Attenuated total reflection (ATR) occurs when light permeates metal films, resulting in a fluctuation in light intensity. Thus, the fluid properties can be determined by measuring the intensity of the light that exits the fluid. Because adding chemicals or agents to the proposed biosensor is unnecessary, the properties of the measured sample are unaffected during measurements. The sensitivity of its strength reached 6.1202 (mw/refractive index).