Patent ID: 8212563

Claim:
An electron-spin resonance (ESR) sensor system, comprising a casing have a top and side walls, with at least one input port and an exit port formed in the side walls, the casing formed such that flow stream path is formed between the input port and the exit port; a resonator cavity formed in the casing, the resonator cavity being formed in the flow stream path such that a fluid sample flowing through the flow stream path passes through the resonator cavity; a magnet assembly attached with the casing and proximate the resonator cavity, the magnet assembly being formed to cause a change in a magnetic susceptibility of a fluid sample flowing through the resonator cavity; an electronic circuit to generate a high-frequency probe signal in the resonator cavity; and a detector to detect the phase or amplitude variations of the probe signal, such that the variations can be used to detect an undesirable by-product component in the fluid sample in the flow stream path.