HANWEI ELECTRONICS CO. ,LTD MG-811 http: //www. hwsensor. com MG811 CO2 Sensor Features Good sensitivity and selectivity to CO2 Low humidity and temperature dependency Long stability and reproducibility Application Air Quality Control Ferment Process Control Room Temperature CO2 concentration Detection Structure and Testing Circuit Sensor Structure and Testing Circuit as Figure, It composed by solid electrolyte layer 1 Gold electrodes 2 Platinum Lead 3 Heater 4 Porcelain Tube 5 100m double-layer steeless net 6 Nickel and copper plated ring 7 Bakelite (8) Nickel and copper Figure 1B plated pin 9 Figure 1AFigure 1A Working Principle Sensor adopt solid electrolyte cell Princip le It is composed by the following solid cells Air Au NASICON carbonate Au, air CO2 When the sensor exposed to CO2 the following electrodes reaction occurs Cathodic reaction 2Li + + CO2 + 1/2O2 + 2e - = Li2CO3 Anodic reaction 2Na+ + 1/2O2 + 2e- = Na2O Overall chemical reaction Li2CO3 + 2Na + = Na2O + 2Li + + CO2 The Electromotive force EMF result from the above electrode reaction, accord with according to Nernsts equation: EMF = Ec - (R x T) / (2F) ln (P(CO )) 2 P(CO ) CO2--- partial Pressure Ec Constant Volume R Gas Constant volume 2 T Absolute Temperature K F Faraday constant From Figure 1B Sensor Heating voltage supplied from other circuit , When its surface temperature is high enough , the sensor equals to a cell, its two sides would output voltage signal ,and its result accord with In sensor testing, the impedance of amplifier should be within 100 1000G Its testing current should be control below 1pA. Tel: 86 371 5333098 5333099 Fax: 86 371 5333090 E-mail: sensor 371.net HANWEI ELECTRONICS CO. ,LTD MG-811 http: //www. hwsensor. com Specifications Symbol Parameter Name Technical Remarks V Heating Voltage 6.00.1 V AC or DC H 30.05% R Heating Resistor Room Temperature H I Heating Current 200mA H P Heating Power 1200mW H -20 50 Tao Operating Temperature -20 70 Tas Storage Temperature E M F 30 50mV 350 10000ppmCO2 Output Sensitivity Figure 2 Shows gas sensor sensitivity curve. Conditions: Tem 28 RH 65% Oxygen 21% EMF: sensor EMF under different gas and concentration . Response and Resume Characteristic Figure 3 shows Solid electrolyte sensor response and resume characteristics. Temperature and Humidity Dependency Tel: 86 371 5333098 5333099 Fax: 86 371 5333090 E-mail: sensor 371.net