Chemical sensing apparatus

Abstract

In an improved amperometric gas sensor, the structure, composition, and electrode potential are adjusted so as to prevent or minimize any unwanted reactivity at the counter and / or reference electrode of any analyte or interfering component of the matrix that may cross over thereto. The sensor is preferably structured so that the product of the analyte reaction at a first working electrode can be reconverted to the original analyte at a counter electrode or at a second working electrode and then reacted again at the first working electrode, with such back-and-forth reactions repeating many times, so as to yield an amplification of the analyte signal.

Description

BACKGROUND OF THE INVENTION [0001] This is a divisional application of application Ser. No. 09 / 015,166, filed Jul. 25, 2001. [0002] This invention relates to improved apparatus and methods for detecting a selected chemical species, hereinafter referred to as “analyte.” My invention concerns sensor devices, advances in analytical capability, and new applications of chemical sensing technology. Although the invention is directed primarily to the detection of gaseous analytes, some of its novel aspects may also apply to liquid and even solid substances. [0003] While the present invention can have broad implications for the improvement of various types of analytical sensors, its focus is on the amperometric gas sensor, hereinafter referred to as “AGS”. [0004] The AGS has been in existence since the Clark electrode of the 50's was developed for measurement of oxygen in blood. The modern carbon monoxide [CO] sensor has existed since 1969 and resulted from the novel application of the Tefl...

AI Technical Summary

Benefits of technology

"The invention focuses on improving the analysis of gases by adjusting the structure of the electrodes and the potential difference between them. This results in the CE and RE having minimal or no reactivity with the analyte, while the WE has maximized reactivity. The invention also allows for the amplification of the analyte signal through back-and-forth reactions between the CE and WE. Additionally, the invention can involve a second WE for the reconversion of the analyte reaction product. These modifications lead to improved accuracy and sensitivity in gas analysis."

Problems solved by technology

This is the typical limit of detection for simple chemical sensors.

Present limitations to sensitivity and selectivity are tied to signal size, noise, drift, and background current of the sensor and ultimately to the choice of: 1) materials used for electrocatalysts [electrodes] and electrolytes, and 2) structure [geometry] and methods of operation of the sensor.

Current CO sensors are not quite adequate for fuel cells, home CO alarms, and micro-noses, and a better sensor would benefit society.

Critical applications like humanitarian de-mining or detection of explosives at airports are not possible with present chemical sensors, indeed with any sensors or analytical instruments, and still rely on the imperfect but elegantly sensitive dog's nose.

The present CO sensor is difficult to use for stack eases and fuel cell automotive vehicles because it has cross sensitivity to many other pollutants and cannot operate effectively above 60° C. The present CO sensor lacks ability to be used on very small samples with high sensitivity and stability and cannot be easily used in the treatment of jaundice in newborn infants.

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