I am interested in measuring the presence (or absence) of a material whose permeability (Mu) isn't much different to free space but the permittivity (epsilon) is. Use water as an example;
Mu = 0.9999xMu0 (permeability)
e = 80xe0
Also in the case of water the conductivity varies widely depending of the dissolved ion concentration (salinity), which I am not interested in, but the permittivity doesn't. This makes permittivity a good candidate for my sensor, it has an order of magnitude change and the change is independent of other conditions I am not interested in. Where permeability isn't so attractive as the effect would be difficult to detect.
In the LDC examples the sensor is used to detect a change in inductance caused by a high Mu material being moved into an engineered inductor's magnetic field.
My understanding is that the LDC measures the change in the impedance of an LC tank, with a fixed C which gives a measurement of L. Further if the coil geometry is fixed it is really a measurement of changes in the dielectric Mu. Can I use it with a fixed inductor and a capacitive sensor engineered so that when the dielectric permittivity changes we see it as a change in the measurement quantity? Is it feasible to construct such a sensor? Is there an easier approach? Am I missing something?
Thanks in advance.