Patent ID: 6359444
Filing Date: 2002-03-19
Classification: G01N,H01Q

Abstract:
A resonant sensing apparatus for operative arrangement within a test environment to which an interrogation electromagnetic field is applied to sense an analyte, comprising:a sensing structure comprising an antenna in electrical communication with a resonant circuit having a capacitive component and an inductive component comprising a plurality of conductive windings, both of which are on a first side of a structural element made of a material that selectively responds to the analyte, said sensing structure operable to resonate at a characteristic resonant frequency in the presence of the interrogation electromagnetic field and the analyte; said structural element comprises a plurality of particle-sized ferromagnetic elements embedded within said material; a remote receiver for measurement of a plurality of values for electromagnetic emission intensity of said sensing structure to identify said characteristic resonant frequency; said plurality of values for electromagnetic emission intensity comprise a plurality of successive values taken over an operating range of successive interrogation frequencies, and said interrogation electromagnetic field is so applied by generating a pulse of electromagnetic energy emitted just prior to each said measurement taken of said successive value; and wherein said antenna is a biconical antenna coupled to an electro-chemical cell and a timing circuit, said pulses being emitted from said antenna at pre-determined intervals for said remote measurement thereof by said receiver; said plurality of conductive windings are patterned onto said first side; and said corresponding series of analyte sensing values comprises analyte pH level values.