Hyodo T.,Nagasaki University |
Goto T.,Nagasaki University |
Ueda T.,Nagasaki University |
Kaneyasu K.,Figaro Engineering Inc. |
Shimizu Y.,Nagasaki University
Journal of the Electrochemical Society | Year: 2016
Potentiometric gas sensors using an anion-conducting polymer as an electrolyte and SnO2 loaded with or without 2.0 wt% Au as an electrode material were fabricated and the CO-sensing properties were investigated mainly in wet synthetic air (57%RH) at 30°C. Loading of Au onto SnO2 powders by precipitation-deposition technique was quite effective in improving the sensing properties to CO and H2, and the magnitude of CO response was larger than that of H2 response. In addition, the CO response was largely dependent on concentration of O2 in the gaseous atmosphere. These results indicate that electromotive force of the sensor is probably determined by mixed potential resulting from CO oxidation and O2 reduction. Heat treatment of the Au-loaded SnO2 powder under reducing atmosphere decreased the H2-sensing properties, and thus largely enhanced the CO selectivity against H2. Especially, the sensor using Au-loaded SnO2 which was heat-treated in H2 at 250°C showed large CO response, the largest CO selectivity against H2, and the fastest response and recovery speeds among all the sensors tested, while storage of the sensor under normal atmosphere weakened the effect of the heat-treatment in H2 at 250°C on the CO-sensing properties. © 2016 The Electrochemical Society.
Figaro Engineering Inc. | Date: 2010-09-16
An output of a direct current power supply is divided with a pair of resistors, and applied to any of electrodes of an electrochemical gas sensor provided with a detection electrode, a counter electrode and a solid electrolyte membrane through a buffer amplifier. Impedance of the gas sensor is measured by switching with a switch the connection destination of one electrode of the electrochemical gas sensor between a current amplification circuit and an impedance measurement circuit. The impedance measurement circuit is formed of an alternating current power supply that switches a potential of a resistor on a side of one end connected to the switch and a potential on a side of the other end of the resistor, between the output potential and the ground potential of the direct current power supply. Gas concentration is determined by storing humidity dependency and temperature dependency of the electrochemical gas sensor, and correcting the output of the current amplification circuit based on measured impedance and ambient temperature.
Figaro Engineering Inc. | Date: 2012-05-23
A gas is detected using a MEMS gas sensor. The electrical power to a heater in the gas sensor is changed between a low level, a high level suitable for detection of detection target gas, and a 0 level, and, therefore, poisonous gas is evaporated or oxidized at the low level, and the detection target gas is detected at the high level.
Figaro Engineering Inc. | Date: 2013-12-12
SEMICONDUCTOR GAS SENSORS FOR MEASURING GAS CONCENTRATION, SOLID ELECTROLYTE GAS SENSORS FOR MEASURING GAS CONCENTRATION, ELECTRO-CHEMICAL GAS SENSORS FOR MEASURING GAS CONCENTRATION, COMBUSTION TYPE GAS SENSORS FOR MEASURING GAS CONCENTRATION, ELECTRIC OXYGEN SENSORS, ELECTRIC HUMIDITY SENSORS, MICRO-COMPUTER FOR DRIVING A GAS SENSOR, GAS DETECTORS FOR DETECTING THE PRESENCE OF GAS.
Figaro Engineering Inc. | Date: 2013-12-13
SEMICONDUCTOR GAS SENSORS, SOLID ELECTROLYTE GAS SENSORS, ELECTRO-CHEMICAL GAS SENSORS, COMBUSTION TYPE GAS SENSORS, ALL FOR THE PURPOSE OF MEASURING GAS CONCENTRATION.