HANDMADE OXYGEN SENSOR AND ITS APPLOCATION FOR SCIENC EDUCATION

化学传感器是激发年轻人对科学兴趣的一种有用的装置。我们制作了一个用于测量氧气浓度的手工氧气传感器，使用方便的工具补充了必要的部件。实验电化学氧传感器可以用两种金属板，一种是传统的可渗透氧气的塑料薄膜，一种是电解质来组装。实验采用金极板为阴极，铅极板为阳极，聚乙烯薄膜为透氧膜，含海藻酸钠的0.1M或0.2M NaHCO_3溶液为电解溶液。这种传感器被称为克拉克电极。利用电阻器测量传感器的减小电流。由于这个由两块金属板和塑料材料组成的身体对学生来说似乎很难制作，所以我们准备了它。大多数商用氧传感器使用强碱溶液作为电解质，但这对儿童是危险的。NaHCO_3水溶液作为电解液是安全的，表现出良好的性能。溶液中的海藻酸钠对于保持金电极和铅电极之间的电接触是必要的。传感器电压与氧浓度在0 ~ 100%氧浓度范围内呈良好的线性关系。我们可以很容易地组装氧气传感器，然而，传感器的响应取决于我们的个人技能。传感器信号通过AD转换器存储在个人计算机系统中。当蜡烛的火焰熄灭时，传感器的输出显示氧气浓度约为17%。这种测氧系统被认为在科学教育中是有用的。

Introduction Chemical sensor would be a useful device for arousing young pepole's rnterrest in science. We preparerd a handmade oxygen sensor for measuring oxygen concentration, supplementing necessary parts by use of convenient tools.Experimental Electrochemical oxygen sensor can be assembled using two kinds of metal plates, a conventional plastic film that is permeable to oxygen, and an electrolyte. A gold plate as the cathode, a lead plate as the anode, a polyethylene film as the oxygen permeable film, and 0.1M or 0.2M NaHCO_3 solution containing sodium alginate as the electrolytic solution were used in this experiment. The sensor is called as Clark electrode. The reduction current of the sensor was measured by use of a resistor.Results and Discussion As it seem to be difficult for students to be make the body which consists of two metal plates and plastic material, we prepared it. A strong base solution is used as the electrolyte in most commercially available oxygen sensors, but this is dangerous for children. Aqueous NaHCO_3 solution is safe as electrolytic solution and showed a good performance. Sodium alginate in the solution is necessary to keep the electric contact between gold and lead electrodes.The relationship between the voltage of the sensor and oxygen concentration showed a good linearity in the range from 0 to 100% of oxygen. We can easily assemble the oxygen sensor, houever, the response of the sensor depends on our personal skill. The sensor signal was stored in a personal computer system through an AD converter. When the flame of the candles died out, the output of the sensor showed an oxygen concentration of around 17%. This system for oxygen measurement was considered to be useful in science educatin.