Handheld instruments


HOW INTEGRATED OPTICAL RECEIVERS FUTURE-PROOF POINT-OF-CARE INSTRUMENTS


In vitro diagnostic (IVD) systems rely on optical receiver techniques to achieve highly sensitive and specific results. Established techniques such as ELISA and PCR utilise a fluorescence optical receive chain to perform diagnostic tests. It is no surprise, therefore, that the point-of-care (PoC) market has also adopted optical receivers as a powerful tool in creating a system that is accurate, flexible, and achieves a fast time to result. This article provides details on key considerations when designing an optical PoC receive chain and how integrated optical front ends can not only meet these performance demands but also provide a key advantage to those striving to create a platform for the future.


FUNDAMENTALS OF FLUORESCENCE DETECTION IN DIAGNOSTICS In a fluorescence-based IVD test, a sample containing fluorescent labels is excited with the light of a specific wavelength as shown by the green arrow in Figure 1. If the sample contains the analyte of interest, the fluorescent labels react to the excitation by emitting a light of a lower energy level. For example, in Figure 1, the fluorescent labels in the sample react by emitting red light. This emitted light is the fluorescence signal that needs to be detected to determine the presence, and possibly the amount, of analyte in the sample. A fluorescence-based diagnostic test will have a threshold of what is considered reportable fluorescence. A fluorescence signal below the threshold level cannot confidently indicate the presence of the analyte in the sample. The electronics in the diagnostic detection instrument, along with other factors, contribute to the background noise, which forces the threshold higher. To reduce the threshold level


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Figure 1. An IVD fluorescence detection system. May 2023 Instrumentation Monthly


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