System for quantifying components in a liquid sample, for example white blood cells in blood, based on use of substantially non-compressible beads of uniform diameter as spacers between a microscope slide and cover slip. The distance between the slide and cover slip is determined by the diameter of the beads, and thus the volume of the sample being viewed can be precisely determined. Prior to use, the beads may be adhered to a microscope slide or stirring rod in a dried adhesive matrix which is soluble in the liquid sample to be examined.

A method for analyzing particles and particularly sediments of urine is accomplished by distributing the sample over an extended area. A plurality of optical still images is taken of the sample, with each image representing a different portion of the area. Each optical image is converted into an electronic image, with the images of the particles in the electronic images. The images of the particles are extracted from the electronic images. The images of the particles are displayed in an ordered array by classes of visually discernible characteristics.

A sensing device for sensing an environmental factor. The device includes a retroreflective layer disposed in a parallel, facing relationship with a sensing layer. The sensing layer has an initial optical absorption capacity for (i) sensing a presence of an environmental factor, (ii) experiencing a change in optical absorption capacity responsive to said environmental factor, and (iii) transmitting and attenuating light. A first portion of the sensing layer is sealed off from exposure to the environment while a second portion remains exposed to the environment such that, when the environmental factor is present, the first portion of the sensing layer is prevented from experiencing a change in optical absorption capacity responsive to said environmental factor. Well-collimated light beams are passed through the sensing layer and are reflected back from the retroreflective layer for processing. When the environmental factor is present, the beams which pass through the second portion are attenuated responsive to an increase in optical absorption capacity and are compared with the non-attenuated beams passing through the first portion to calculate the presence and quantity of the environmental factor.

A novel material and device useful in solid-phase binding assays to determine the presence or amount of an analyte in a test sample, particularly antigens, antibodies, or other ligands or DNA segments. The material and device comprises a reaction site having procedural controls and an analyte binding area capable of being simultaneously contacted by the sample and reagent used in the performance of the assay. The procedural controls and analyte binding areas operate to provide readable results as to the presence or absence of analyte and simultaneously verify the assay procedure and therefore the assay result.

A fluorometer for sensing the fluorescence of a sample utilizes an optical energy source for exciting a sample to be tested and an optical energy detector for detecting the emitted energy from the excited sample. Drive electronics are used for positioning the sample with respect to the optical components allowing a plurality of sample regions to be tested. A processor is utilized to control the operation of the test in accordance with test instructions and for processing the emitted energy detected from the sample to determine test results. A ROM chip socket accepts a plurality of ROM chips, wherein each ROM chip stores test data sets for one or more test types to be performed. ROM chips can be swapped to allow the fluorometer to be configured and reconfigured to perform a plurality of different tests. A communications interface facilitates the sharing of test information between the fluorometer and external entities.