电化学与传感器

-电化学原理、方法和应用-
Applications
Monitor waste stream discharges.
Monitor composition of plating baths and rinse systems.
Monitor levels of key ingredients in oils and lubricants.
Monitor pollutants.
Monitor corrosion processes.

Extremely versatile sensors
As a class of sensors, electrochemical sensors constitute one of the broadest and oldest types. For quantitative measurements, they are particularly useful for the analysis of inorganics in complex aqueous matrices. They can be used for the detection of metal ions such as Cu+2, Pb+2, Zn+2, etc., at the sub-part-per-billion level. Complex mixtures of metal ions are also easily determined. The use of electro-chemical sensors to measure nonmetals such as CN-, Cl-, Br-, and many others, and pH is well documented.

Advantages of electrochemical sensors
Where optical sensors may fail, perhaps because of opacity of the medium or because the analytes are not optically active, electrochemical sensors may have advantages. In addition, recent developments in chemically modified electrode sensors, microelectrodes, and voltametric and potentiometric methods (such as adsorptive stripping voltametry and potentiometric stripping analysis) has opened the door for the application of electrochemical sensors to the analysis of many more inorganic ions. Even some anions that are not electrochemically oxidizable or reducible have been analyzed using polymer modified electrodes. Finally, in contrast to atomic spectroscopic techniques, instrumentation for electrochemical analysis can be made compact.

The revolution in laboratory instrumentation that has occurred within the past 10 to 15 years has been well received by laboratory workers. However, because of the pressing need for instrumentation for field environmental studies and real-time analyses, additional work must be undertaken. In particular, instrumentation needs to be made even more portable and more automated (user-friendly). Multiple species detectors must be included.

Multiple-element microelectrode array sensors
It is for these purposes that we have developed multiple-element microelectrode array sensors and a compact electronics system (potentiostat and controller) for experimental control and data acquisition. Photolithography has been used to fabricate the microelectrode arrays. Various materials, such as gold, platinum, carbon, silver, and others, are used in its construction. Following deposition, chemical or physical techniques can be used to modify the individual elements of the sensor so that they are chemically selective. In this manner, one can develop a sensor which, for example, can simultaneously monitor Cu+2, Pb+2, CN-, Ag+1, pH, etc.

Hand-held instrument
As mentioned above, we have also developed a hand-held electronic system (potentiostat/controller) to acquire data in the field using the arrays. It is a multichannel instrument that can access up to eight elements of the array in any order. This instrument weighs only 0.76 kg and is equipped with a battery pack. It can also be equipped with a UHF link for radio communication.

Multiple applications
The electrochemical sensor system we have developed is specifically designed to help solve some of the environmental problems facing the DOE laboratories and plants, although it certainly has a much wider range of applications. Some of the applications include monitoring waste streams for the discharge of toxic metals, contamination resulting from mining operations, and the quality of drinking water; minimizing waste in metal plating and finishing; and biomedical applications.