Abstract: The present invention is directed to a process for complex, high density microcircuits in which thick film dielectric pastes are photolithography patterned into high resolution stencils to produce complementary conductor circuitry patterns, the voids of the developed dielectric stencil are filled with thick film conductor paste, and then there is a cofiring of the conductor and the dielectric. With this new process the number of separate firing operations is reduced. The reduction in the number of firings is important in multilevel hybrid structures.

Abstract: A continuous method and apparatus for the determination of urea in a biological fluid such as blood, for example, is disclosed. In a continuously flowing system, the biological sample is introduced into a buffered carrier solution of low electrical conductance and is caused to flow into a chamber containing an immobilized enzyme which catalyzes a specific reaction which changes the electrical properties of the solution by increasing the dissociated ion concentration therein. This increase in dissociated ion concentration is directly proportional to the original concentration of urea in the biological sample; and any one of the several conventional electrical measurements may be made to determine the increase in such concentration or the rate of increase in such concentration and thereby determine the concentration of urea in the original biological sample.