1. Incubator Structure An overview of the mechanics of incubators supplied by Research Instruments in the UK & Ireland With thanks to Astec Japan Co- author Rob Watkins Research Instruments

3. Incubation Area Water Jacket Heater

4. Styrene foam Glass Wool Water Jacket

5. Heater Temperature Sensor A Sensor A maintains the water of a water jacket at fixed temperature. Temperature Sensor B Sensor B is a temperature sensor for displaying the temperature of the incubation area.

6. R1R2 Dry airAir THERMISTOR It is the structure measured by the difference of the thermal conductivity of damp air and dry air. Current is passed so that the self-exothermic temperature of each THREMISTOR might become about 200 degrees. The method of converting the difference of the resistance ingredient by temperature change of the THERMISTOR itself into humidity by the heat conduction by steam is measured. It turns out that it is influenced by other gases, and only the error ingredient of the output to CO2 gas is detected. The output of this absolute humidity converts into CO2 gas concentration, and is measured and used as the reference. Hole

7. 0.51.01.52.02.5 5 0.5 10 0 -5 -10 humidity absolutely (g/m ) 3 Concentration (%) CCl 2 F 2 CO 2 CH 4 H2H2 Influence of mixing of gas The principle of THERMISTOR formula CO 2 sensor

8. Requires fixed temperature Requires fixed humidity ☞ ☞

9. IR light sourceIR Detector CO 2 IR light If the infrared rays from a light source go into a sample cell, specific wavelength will be absorbed by CO 2 gas in a cell. The amount of absorption increases, so that the concentration of CO 2 is high, and the amount of penetrations on the Detector decreases. The result is a method which measures the It will be absorbed if there is much CO 2. IR SENSOR Graphical Representation

10. ThermistorsInfrared (IR) formula Readily available easy to producre Influenced by humidity Influenced by temperature Cheap to end user Readily available but costly to produce Not influenced by humidity Not influenced by temperature More Expensive

11. Incubation area Water jacket (for temperature control) (for a temperature display) THERMISTOR A THERMISTOR B Two temperature sensors are used. By keeping the water temperature of a water jacket constant with THERMISTOR B, it uses that the temperature and turns into fixed temperature within the culture space. THERMISTOR A is used in order to display the temperature in area but this is maintained by probe B.

12. A THERMISTOR is a heat semiconductor from which resistance changes in temperature are monitored. Is was not built for that initial purpose. It is the structure that allows us to detect temperature by passing and investigating the resultant resistance. The THERMISTOR is adopted as a temperature sensor.

13. The characteristic of temperature-resistance of a THERMISTOR When temperature changes, it has the characteristic that internal resistance changes.