Importance

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Abstract

The present invention is a novel, ultra-small tip, internal referenced, amperometric microbiosensor that uses an immobilized biological interface to measure the concentration of an analyte in a specimen. It consists of a casing that narrows to an aperture having a diameter at the tip no greater than 4 .mu.m; enclosed within the casing a reference electrode and a working electrode both immersed in electrolyte; within the aperture, an inner polymer film, an immobilized biological interface layer, and an outer specimen-compatible, non-virulent polymer film. Another important feature of the present invention is that the microbiosensor can readily be encased in a durable protective sheath. The microbiosensor is especially useful in situ for specimens that cannot be mixed, such as in situ compounds in unmixed fluid, or semi-solid specimens. The microbiosensor provides 90% response time less than 5 seconds and typically about 1 second, less than 5% change in output current due to changes in the stirring rate, and the ability to measure in viscous, semi-solid or porous-solid specimens with a spatial resolution as small as 30 .mu.m.

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First Claim