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US 7,479,864 B2Granted
Total fluid conductivity sensor system and method
OwnerThomas M. Weller, David P. Fries +1inventors
InventorsThomas M. Weller, David P. Fries, Saravana P. Natarajan
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Abstract
The present invention provides an apparatus and method for measuring the conductivity of a fluid employing the differential radio frequency phase detection between two embedded toroidal coils.
Claims13
A fluid conductivity sensor embedded in a printed circuit board, the sensor comprising:
- a first toroidal coil embedded in a printed circuit board and a second toroidal coil, the first coil positioned in close proximity to the second coil to establish a toroidal inductor having a core of dielectric material;
- and
- a radio frequency phase detection circuit coupled to the toroidal inductor to detect the conductivity of the fluid, the radio frequency phase detection circuit further comprising;
- a voltage controlled oscillator tuned to output a radio frequency signal;
- a coupler coupled to the voltage controlled oscillator to generate a reference signal and an output signal from the radio frequency signal, the output signal of the coupler received as an input signal to the first toroidal coil;
- an amplifier to receive an output signal from the second toroidal coil in response to the input signal to the first toroidal coil;
- and
- a frequency mixer to receive the reference signal from the coupler and the output signal from the second toroidal coil, and to output a phase difference signal representing the difference between the reference signal from the coupler and the output signal from the toroidal coil.
5 more elements
A method for measuring the conductivity of a fluid, the method comprising the steps of:
- placing a first toroidal coil embedded in a printed circuit board and a second toroidal coil within a fluid to be measured, the first coil positioned in close proximity to the second coil to establish a toroidal inductor having a core of dielectric material;
- establishing a radio frequency signal;
- splitting the radio frequency signal to generate a reference signal and an output signal from the radio frequency signal;
- providing the output signal as an input signal to the first toroidal coil;
- establishing an output signal from the second toroidal coil in response to the input to the first toroidal coil;
- amplifying the output signal from the second toroidal coil;
- and
- measuring the phase difference between the amplified output signal from the second toroidal coil and the reference signal, the phase difference representative of the conductivity of the fluid.
5 more elements
Dependencies are inferred from the claim text.