A sensor can be configured to generally include a flow channel block having a flow channel formed therein, and a sensor
chip for sensing fluid flow, wherein a fluid in the flow channel surrounds the sensor
chip. Alternatively, the sensor
chip can be fastened at one side to a substrate and on another side of the substrate to a core tube inserted into the flow channel. This core tube provides electrical insulation and
corrosion protection to the sensor chip, reduces flow
noise, (and by the non-intrusive nature of the measurement) essentially eliminates the risk of
fluid leakage, and maintains the fluid super-clean and
contamination-free while improving
structural integrity for the thermal measurements derived from the sensor chip. The use of such a core tube configuration also can protect the sensor from
corrosion, radioactive or bacterial
contamination, overheating, or freeze-ups. Such a core tube configuration also enables the core tube to be detachable and disposable, without requiring the replacement of the more costly sensor chip with its
electronics and calibration.