Development of O_2 and CO_2 measurement system for science education

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In this study, we developed an easy-to-operate O_2 and CO_2 measurement system for science education. We used an easily-prepared hand-made diaphragm galvanic cell-type sensor as the O_2 sensor. This O_2 sensor can measure not only the oxygen concentration in air, but also in a solution, making it suitable as an educational tool. We used a solid electrolyte-type sensor module as the CO_2 sensor.This system makes automatic and simultaneous measurements of O_2 and CO_2 concentration possible using the combination of the O_2 and CO_2 sensors. We also developed measurement software using commercially available spreadsheet software by connecting the sensor with a PC using a USB connection. The most important advantage is to be able to visualize the changes in the concentration of invisible and odorless gases such as O_2 and CO_2 as a function of time.We measured the author's expired air using the O_2 and CO_2 measurement system, measuring both shallow and deep expirations. First, shallowly i … More nhaled air is exhaled into an expiration bag. Then, air is deeply inhaled and held for 30 seconds before being exhaled into the bag. We sampled the air every 5 seconds and measured the O_2 and CO_2 concentration of each sample for 90 seconds.In respect to the results, the O_2 concentration in shallow expiration was decreased from 20.8% to 18.6%. On the other hand, the CO_2 concentration was 17, 8ppm, which was an increase the atmospheric CO_2 concentration. The O_2 concentration in deep expiration was observed to decrease by about 4.1% from 20.9% to 16.8%. On the other hand, the CO_2 concentration was 2, 4ppm.In conclusion, anyone can easily measure changes in the O_2 and CO_2 concentration as a function of time in shallow and deep expiration using an expiration bag and the sensor system. We can also carry out experiments easily and obtain highly accurate data. This sensor system can be expected to promote the basic concept of"Life"as an educational tool for the study of natural science. Less