Abstract: A method of measuring an analyte present in animal (e.g., human) tissue or fluids such as blood or plasma. The analyte is multi-photon excitable (e.g., two-photon excitable) at a first wavelength at which the animal tissue is substantially non-absorbing. The analyte fluoresces at a second wavelength upon being excited at the first wavelength. The animal tissue is irradiated with radiation at the first wavelength so as to excite the analyte through absorption by the analyte of two or more photons of the radiation at the first wavelength. Excitation of the analyte results in a fluorescent emission from the analyte of radiation at the second wavelength. The emission at the second wavelength is detected, and the concentration of analyte determined based on the detected emission.

Abstract: A method for determining pH or pCO.sub.2 using luminescent lifetimes and energy transfer in which an energy transfer donor-acceptor pair is exposed to a sample to be analyzed, the donor of the donor-acceptor pair being photoluminescent and the acceptor of the donor-acceptor pair being sensitive to the pH or pCO.sub.2 of the sample. One or both of the donor-acceptor pair may be bound to a carrier. The sample is irradiated and the resultant emission detected. By measuring the apparent luminescent lifetime, the pH or pCO.sub.2 of the sample can be determined.

Abstract: A fluorometric luminescence immunoassay method includes forming a sample by exposing a first immune reaction reactant to a second immune reaction reactant capable of reacting with the first reactant, one of the first and second immune reaction reactants being labelled with a photoluminescent energy transfer donor and the other being labelled with a photoluminescent energy transfer acceptor complementary to the photoluminescent donor. At least the photoluminescent donor has the property of photoluminescence, and the photoluminescent donor and acceptor are chosen so that when the first immune reaction reactant reacts with the second immune reaction reactant, the donor and the acceptor are capable of interacting to produce a detectable luminescence lifetime change. The sample is excited with radiation, and the resulting emission is detected. The apparent luminescent lifetime is then calculated to determine the presence of a reaction product of the first and second immune reaction reactants.

Abstract: An apparatus and method to enable minimally invasive transdermal measurements of the fluorescence lifetime of an implanted element without reagent consumption and not requiring painful blood sampling. The monitoring apparatus displays the quantity of a selected substance present in the skin and stores the data in memory. The stored information can be transmitted via modem, or antenna, to a master station for diagnostic purposes or clinical evaluation. The use of this method and apparatus improves control of blood monitoring, and therefore, enhances long-term disease management with fewer complications.

Abstract: A system and method in which a photoluminescent ligand is added to a sample to be analyzed in the form of a photoluminescent probe having intrinsic analyte-induced lifetime changes. The method preferably employs phase-modulation fluorometry to measure the lifetime changes. Specific probes are disclosed for measuring various analytes, particularly ionic solutes, including H.sup.+, Ca.sup.2+ and K.sup.+.

Abstract: A method and apparatus for identifying individual particles or cells which have been labeled with different fluorochromes, on the basis of the lifetime of their fluorescence, or based on different decay times for a fluorochrome in different cells.

Abstract: A method and apparatus for detection and/or measurement of physical characteristics of a sample based on multi-dimensional phase-modulation fluorescence lifetime imaging using at least one fluorescent probe having known and/or variable fluorescent lifetimes.