Method and sensor for detecting presence or absence of a contaminant

A method of detecting a contaminant in a measurement chamber of a sample analyzer, wherein the sample analyzer comprises an optical sensor with a sensor layer comprising a luminophor, wherein the sensor layer has a sensor surface forming an interface to a fluid sample present in the measurement chamber, the method comprising:

• a. filling the measurement chamber with a fluid sample;
• b. applying a stimulus to the luminophor in the sensor layer;
• c. detecting luminescence emitted from the luminophor in the sensor layer in response to the stimulus as a function of time;
• d. obtaining a time sequence of measurement values for the detected luminescence;
• e. based on the time sequence, determining an actual value of a first parameter and an actual value of a second parameter, wherein one of the first and second parameters is sensitive to a change in refractive index across the interface between the sensor layer and the measurement chamber, and wherein the other one of the first and second parameters is not sensitive to said change in refractive index across the interface between the sensor layer and the measurement chamber;
• and
• f. providing feedback on a contamination state based on the actual value of the first parameter and the actual value of the second parameter.

An optical sensor for the detection of a contaminant, the optical sensor comprising a sensor layer with a sensor surface forming an interface to a sample space, stimulus means, detection means, data storage means, and a signal processor,

• wherein the sensor layer comprises a luminophor adapted to emit luminescence radiation in response to an excitation stimulus applied to the luminophor;
• wherein the stimulus means is arranged for providing an excitation stimulus to the luminophor in the sensor layer;
• wherein the detection means is arranged to detect luminescence radiation emitted by the luminophor in response to the excitation stimulus;
• wherein the data storage means comprises programmed instructions for:
• receiving a time sequence of measurement values for detected luminescence as signals from the optical sensor as an input;
• determining an actual value of a first parameter and an actual value of a second parameter, based on the time sequence, wherein one of the first and second parameters is sensitive to a change in refractive index across the interface between the sensor layer and the sample space, and wherein the other one of the first and second parameters is not sensitive to said change in refractive index across the interface between the sensor layer and the sample space;
• providing feedback on a contamination state based on the actual value of the first parameter and the actual value of the second parameter,
• wherein the signal processor is operable to execute said programmed instructions so as to produce an output indicative of the feedback on a contamination state.

A software product that can be loaded to a processor, the processor being configured for communicating with an optical sensor comprising a sensor layer, the sensor layer comprising a sensor surface facing towards a sample space, the sensor layer comprising a luminophor, the processor being further configured for controlling stimulus means adapted for exciting the luminophor, the software product comprising instructions for:

• (i) operating stimulus means to apply a stimulus to the luminophor in the sensor layer;
• (ii) operating the optical sensor to detect luminescence emitted from the luminophor in the sensor layer in response to the stimulus as a function of time;
• (iii) obtaining a time sequence of measurement values for the detected luminescence;
• (iv) based on the time sequence, determining an actual value of a first parameter and an actual value of a second parameter, wherein one of the first and second parameters is sensitive to a change in refractive index across the interface between the sensor layer and the measurement chamber, and wherein the other one of the first and second parameters is not sensitive to said change in refractive index across the interface between the sensor layer and the measurement chamber;
• (v) providing feedback on a contamination state based on the actual value of the first parameter and the actual value of the second parameter.