According to the WHO, tuberculosis is the second deadliest infectious disease worldwide after COVID-19. To counter the multi-resistance of tuberculosis bacteria, which is becoming more and more prevalent against antibiotics, suspected cases have to be tested daily and, in case of a positive laboratory result, treated and isolated quickly. As a rule, however, the necessary laboratory infrastructure and logistics are lacking, because 95 per cent of tuberculosis cases occur in developing and emerging countries.

The overall goal of FluoResYst is to develop a rapid point-of-care detection system for multidrug resistance that can help to contain epidemics by accelerating on-site diagnostics outside of laboratories. The combination of photonic integration of time-resolved fluorescence measurement for short-lived fluorochromes and the biochemical fluorescence quenching antibody assay is expected to greatly simplify complex analyses that were previously difficult to access and thus make them widely available.

In the technological part, a photonic platform is being developed for this purpose, which is to enable tuberculosis diagnostics outside a laboratory environment through a high degree of integration. The principle of the detection platform is based on time-resolved fluorescence measurement, with which complex optics and wavelength filters can be largely avoided. This is made possible by the use of a very fast excitation laser and a fast CMOS-integrated detector.

In the project, IMMS is developing this detector chip for reading out DNA microarrays. In addition to several arrays of single-photon avalanche diodes (SPADs), the chip also contains the histogram generators required for their evaluation. By the use of through-silicon vias (TSVs), the chip with its planar surface can be integrated very well into microfluidic systems. In addition to the SPADs, classical photodiodes are also distributed and evaluated in the chip, which relaxes the requirements for the homogeneity of the optical excitation and further reduces the device complexity.