低造價溶氧感測器之設計與研發

Abstract

在水產養殖的過程中，常因多種因素影響，造成池水發生缺氧現象，導致魚類死亡。有鑑於國內使用之溶氧感測器均仰賴國外進口，僅感測頭部份的單價約需0.5~2萬元間，因此建立一個養殖空間之監測系統，單在購買溶氧感測器的費用即為一龐大支出。本研究利用溶氧感測器的低造價設計與組裝，發展簡易自製溶氧感測器系統。 本研究以伽瓦尼電池（Galvanic cell）原理之電氣化學反應作為感測器設計的基礎，並根據氧化還原反應所產生之電壓大小與水中氧氣量成正比，以計量水中的溶氧量。本研究自製溶氧感測器使用的金屬材料以銀、鋅電極組合，透氣膜採用PE保鮮膜，電解液使用KCl(aq)，感測器外殼為市售塑膠殼，以一般電線作為電流導線等組合而成。探討溶氧感測器之電流導線長度、電解液濃度、電解液容量等設計變因，對感測器的靈敏度與老化速度等影響。得知電流導線長度在15m內不影響反應結果；感測器之電解液填充17cc的1M KCl(aq)，電壓訊號至少在四個月內可呈穩定反應。製作一個感測系統的材料成本約為350元。

The process of aquaculture is frequently affected by many factors, that cause oxygen deficit phenomena in the water and lead to death of fish . Since the dissolved oxygen sensor remain high in price, it would cost substantial expenditure to establish a monitoring system for cultivation .Therefore, this research utilizes low cost sensor design and assembly to develop simple and self-operated oxygen dissolving detecting system. The foundation of developing the economical sensor is adoping Galvanic cell. The voltage magnitude and the dissolved oxygen is correlated according to oxidation-reduction reaction. The dissolved oxygen sensor is composed of Ag + Zn electrode, P.E. membrane, KCl solution, plastic shell, and wires. The sensitivity and aging speed of the detecting device may be influenced by several factors, including wire length, electrolyte concentration, the capacity of electrolyte, and so on. It is concluded that the wire length below 15 meters has no influence reaction results ; the electrolyte of 1M KCL (aq) in the sensor with the volume of 17c.c. reached its full efficiency, and the voltage signal would provide stable response over four months. The total cost to fabricate a dissolved oxygen sensor is kept under NT$ 350.