Abstract: A device for detecting the presence of a predetermined reactant in a fluid suspected of containing the same which comprises a pyroelectric film having a first and a second surface, a first electrode in contact with a portion of the first surface of said pyroelectric film, a second electrode in contact with a portion of the first surface of said pyroelectric film, said first and said second electrodes being proximate to but electrically insulated from each other, an infra-red transparent third electrode having a first and second surface, said first surface being in contact with the second surface of said film, methods of making such a device and methods of utilizing same.

Abstract: There is provided a novel method of testing for the presence of an analyte in a fluid suspected of containing the same. In this method, in the presence of the analyte, a substance capable of modifying certain characteristics of the substrate is bound to the substrate and the change in these qualities is measured.While the method may be modified for carrying out quantitative differential analyses, it eliminates the need for washing analyte from the substrate which is characteristic of prior art methods.