Patent ID: 6140048
Filing Date: 2000-10-31
Classification: C12Q,G01N

Abstract:
A system using time-resolved fluorescence measurement for distinguishing between at least two different types of fluorescent groups that are bound to analyte molecules in a sample, comprising(1) a light source which emits a light to illuminate a first sample volume, which light is suitable for exciting said fluorescent groups to fluorescence;(2) a detector for detecting fluorescence radiation emitted from fluorescent groups in a second sample volume to generate signals, wherein said second sample volume at least partially overlaps with said first sample volume forming an overlapping sample volume of about 0.05 to 10 femtoliters;(3) a control unit which performs at least 1,000 cycles per millisecond, wherein in each cycle said control unit(a) activates said light source for a time interval T.sub.1 to illuminate said first sample volume;(b) waits for a time interval T.sub.2 ; and thereafter(c) activates said detector for a time interval T.sub.3 to detect fluorescence radiation emitted from fluorescent groups in said second sample volume generating signals;(4) a recording unit which records the signals from said detector; and(5) an evaluation unit which uses a duration of fluorescence obtained from said signals gathered in T.sub.3 over time to determine which of said at least two fluorescent groups is bound to said analyte molecules present in said overlapping sample volume.