Patent ID: 6973834
Filing Date: 2005-12-13
Classification: G01L

Abstract:
1. A method of measuring the pressure of a fluid medium, comprising: immersing within the fluid medium an electrical resistor having a resistance varying with temperature; applying electrical current through the electrical resistor to heat it to a predetermined temperature above that of said fluid medium; and measuring the rate of change in resistance of said electrical resistor to produce a measurement of the rate of thermal heat dissipation, varying with the density of the fluid medium in which the electrical resistor is immersed, and thereby a measurement of the pressure of said fluid medium; wherein said electrical resistor is a positive temperature coefficient thermistor driven by a constant voltage source and having a resistance which increases sharply at said predetermined temperature, such that the thermistor is automatically self-controlled to substantially maintain said predetermined temperature, whereby the electrical current drawn by said thermistor is a measurement of the thermal load on the thermistor resulting from the thermal heat dissipation therefrom, and thereby a measurement of the pressure of the fluid medium.