| 摘要 |
The present invention relates to a sensing instrument and method for measuring the concentration of an analyte. The sensing instrument includes a sensing element including at least a first emissive indicator characterized by a bimolecular quenching rate constant kq, one or more fluorescence lifetimes tau o above a lowest lifetime tau oL, and capable of emitting analyte concentration dependent signals when exposed to an excitation signal in the presence of quencher. An excitation system coupled to the sensing element provides an amplitude modulated excitation signal at one or more radial modulation frequencies omega . A detector coupled to the sensing element detects the analyte concentration dependent signals and provides detected signals. A processor, preferably including memory for storing information characterizing a calibration relationship between analyte concentration and the concentration dependent parameter is coupled to the detector. The processor univariantly processes the detected signals and provides output signals representative of analyte concentration. The sensing element and/or excitation system are configured to enable the instrument to operate sufficiently within the condition [(kq[Q])<2>+ omega <2>] tau o<2> >> 1+2kq tau o[Q] such that a slope of the relationship between the concentration dependent parameter and anlayte concentration is independent of tau o variability and/or heterogeneity for all analyte concentrations within the operating range and for all lifetimes tau o greater than tau oL. When configured in this manner the calibration slope is independent of tau o variability and/or heterogeneity. The sensor can therefore be recalibrated by modifying the stored calibration information characterizing the intercept, but not the slope, of the relationship in response to sensing element exposure to one calibration analyte of a known concentration. |
