Handmade oxygen and carbon dioxide sensors for monitoring the photosynthesis process as instruction material for science education

The handmade oxygen sensors could monitor the oxygen consumption process in a container where a candle or a disposable pocket warmer was placed. The generation and consumption process of oxygen and carbon dioxide in the photosynthesis using spinach leaves was also monitored in real-time. The photosynthesis apparatus was easily constructed by using a commercially available fluorescent lamp, spinach leaves, and a PET bottle or a desiccator container. A commercially available polyethylene film that is permeable to oxygen and an electrolyte were examined to assemble an electrochemical sensor. The change of carbon dioxide concentration could be measured easily using an electrochemical carbon dioxide sensor. From the light–dark reaction, the carbon dioxide concentration was observed to decrease with increase in the oxygen concentration. Useful instruction tools for chemistry and biology students could be proposed.