Microwave measurement: Microwave cavity sensor tests fluids in situ without having to remove a sample

摘要

A DEVICE that uses microwaves to measure impurities in liquids could be used to detect contaminants in blood, moisture in aircraft fuel and let drivers know when brake fluid needs changing. Oxford University's technology transfer company, Isis Innovation, is planning to commercialise its active microwave cavity sensors to market. Isis claims that unlike similar devices, its solution can test fluid in situ without having to remove a sample, and offers a high Q (quality) factor. The Q factor of a resonator is a function of the energy stored per cycle of oscillation compared with the energy dissipated per cycle of oscillation. A high Q factor means that the loss in the active cavity resonators is significantly smaller, giving a high signal-to-noise ratio - a measure of sensitivity.