A biosensor system, said biosensor system comprising: an apparatus for detecting photoluminescent light emitted from a sample comprising photoluminescent particles, said apparatus (200; 300) comprising: at least one light source (210; 310, 318), which is configured to emit light of a first and a second wavelength towards the sample, wherein said first wavelength is an excitation wavelength for inducing photoluminescent light from said photoluminescent particles, and wherein said second wavelength is at least 20 nm longer than said first wavelength and for gathering background noise information from said sample, a photo-detector for detecting light incident on the photo-detector; an interference filter (204; 304) arranged on the photo-detector; and a receiver for receiving a sample holder (106; 406) wherein the receiver is configured to define a spatial relation between a sample in the sample holder and the interference filter (204; 304); said biosensor system further comprising the sample holder for receiving as the sample a body fluid sample and for pre-processing the sample, the sample holder being configured to be arranged, via the receiver, in the apparatus (200; 300) for allowing the apparatus (200; 300) to excite photoluminescence in the body fluid sample and collect and detect supercritical angle light from the body fluid sample, wherein, in use, the sample holder and the interference filter are arranged for propagation of supercritical angle photoluminescent light, emitted by photoluminescent particles in the sample, through a wall of the sample holder (106,406) and further into the interference filter; wherein the interference filter (204; 304) is configured to selectively collect and transmit light towards the photo-detector based on an angle of incidence of the light towards the interference filter (204; 304), wherein the interference filter (204; 304) is configured to selectively transmit the supercritical angle light, emitted from the sample, towards the photo-detector and suppress undercritical angle light from the sample. at least one light source (210; 310, 318), which is configured to emit light of a first and a second wavelength towards the sample, wherein said first wavelength is an excitation wavelength for inducing photoluminescent light from said photoluminescent particles, and wherein said second wavelength is at least 20 nm longer than said first wavelength and for gathering background noise information from said sample, a photo-detector for detecting light incident on the photo-detector; an interference filter (204; 304) arranged on the photo-detector; and a receiver for receiving a sample holder (106; 406) wherein the receiver is configured to define a spatial relation between a sample in the sample holder and the interference filter (204; 304); said biosensor system further comprising the sample holder for receiving as the sample a body fluid sample and for pre-processing the sample, the sample holder being configured to be arranged, via the receiver, in the apparatus (200; 300) for allowing the apparatus (200; 300) to excite photoluminescence in the body fluid sample and collect and detect supercritical angle light from the body fluid sample, wherein, in use, the sample holder and the interference filter are arranged for propagation of supercritical angle photoluminescent light, emitted by photoluminescent particles in the sample, through a wall of the sample holder (106,406) and further into the interference filter; wherein the interference filter (204; 304) is configured to selectively collect and transmit light towards the photo-detector based on an angle of incidence of the light towards the interference filter (204; 304), wherein the interference filter (204; 304) is configured to selectively transmit the supercritical angle light, emitted from the sample, towards the photo-detector and suppress undercritical angle light from the sample.