veerubiji

Hi, I am confusing in calculating permitivity of the fluid. Permittivity differs from one fluid to another. Ɛ=ƐrƐ0. Since it is an electrical property combined with an electrical capacity, it is possible to measure it indirectly in a capacitive sensor. I have used capacitive sensor to measure electric relative permitivity factor of a dielectric medium can be expressed as a ration of capacity, Cx of capacitor, which space between and around the electrodes is completely filled with the medium, to capacity C0 of the same electrodes in vacuum. Ɛr= Cx/C0. I know and measured C0 value. I am facing problems with calculating Cx of capacitor, which space between and around the electrodes is completely filled with the medium. I am using method as described below. I am applying an A.C signal (125 KHz) to the capacitive sensor which is filled with some fluid, in response I am getting A.C signal with some phase difference. I am able to measure the amplitudes of sensor input, sensor output signals and their phase difference also. I am trying to make equation that will give Cx value from above known values (Vg (input), Vr (output), ᶲ (phase difference)). Any help appreciated. Please help me.

Hi, I am generating sine signal with 125 KHz using micro controller and giving it to Capacitive(cylindrical shape) sensor. If the sensor out is low to read then i am using two amplification stages to increase signal amplitude. I am using multiplexer to select best signal from sensor out. The out signal also 125 KHz but there is a phase shift in the signal based on medium between electrodes. Now I want to calculate phase shift between two signals(vg and vr) as well as both signal amplitude. I am confusing which circuit will gives max amplitude of both signals and phase shift between two signals? I am able to read phase shift and amplitude of both signals using micro controller. I can use ADC to read amplitudes but i am worrying about phase shift.? I am attaching simple block diagram of my circuit as shown below. Any suggestions which circuit will gives phase shift as well as amplitude of input and output?