Gas sensor based on protonic conductive membranes

Abstract

A low cost room temperature electrochemical gas sensor for sensing CO and other toxic analyte gases has a solid protonic conductive membrane with a low bulk ionic resistance. A sensing electrode and a count counter electrode, which are separated by the membrane, can be made of mixed protonic-electronic conductors. Embodiments of the inventive sensor also include an electrochemical analyte gas pump to transport the analyte gas away from the counter electrode side of the sensor. Analyte gas pumps for the inventive sensor include dual pumping electrodes situated on opposite sides of the membrane, and include a means for applying a DC power across the membrane to the sensing and counter electrodes. Another embodiment of the inventive sensor has first and second solid protonic conductive membranes, one of which has a sensing electrode and a counter electrode separated by the first membrane, and the other of which has dual pumping electrodes situated on opposite sides of the second membrane.

Description

FIELD OF THE INVENTION[0001]The invention relates to electrochemical gas sensors, and particularly relates to electrochemical gas sensors having a sensing electrode, a counter reference electrode, and a solid proton conductor for room temperature detection of the concentration of carbon monoxide (CO) in the ambient.BACKGROUND OF THE INVENTION[0002]In most prior art solid state commercial gas sensors, it is necessary to heat the sensor element to elevated temperatures in order to acquire both fast response time and high sensitivity to objective gases. For example, N-type semiconductor tin oxide gas sensors and catalytic combustion type Pd / Pt gas sensors must usually be operated in a temperature range of ca. 200° to 500° C. These sensors must be equipped with heaters connected to external power sources. Therefore, room temperature CO gas sensors, which use less power, are desirable.[0003]It is well known that CO reacts with moisture in air at room temperature, and forms protons, elect...

AI Technical Summary

Benefits of technology

The invention is a low-cost electrochemical gas sensor that can detect toxic gases like carbon monoxide and other analyte gases like H2, H2S, H2O vapor, and NOx concentrations. It has a fast response and strong signal to the detection of gaseous CO in the ambient. The sensor has a sensing electrode and a counter electrode, which can be made of mixed protonic-electronic conductors to encourage a high surface area for reactions and a continuity in the transport of electrical charges. This allows for a fast and strong signal response by the sensor in the presence of the analyte gas.

Problems solved by technology

The cost of the sensor with such a complicated design, however, is high and is thus not be suitable for practical consumer applications.

In addition, the sensor requires maintenance due to leakage and corrosion of liquid electrolyte.

Due to the limited three-phase contact areas in the tubular design sensor, the CO reaction was slow.

Apparently, the internal resistance of the sensor was too large.

Images