Chemical Sensors and Measurement in Process Control (Part Ⅱ)

摘要

his is the second in a three-part series on chemical sensors and measurements, which includes automatic controllers. In April's issue, I discussed "basic sensors" in PCB manufacturing such as visual methods, wet chemistry, temperature, volume/count, electrochemical, specific gravity, and colori-metric. This column explores "Intermediate Devices and Advanced Instruments" such as spectrophotome-ters and Amperes-hour. Advanced systems include electro-analytical (voltametric), liquid chro-matagraph, ion chromatagraph, gas chromatagraph, atomic adsorption (AA), combination (nuclear), and ChemFET/ChemResistors.