On-chip fluorescence detection with organic thin film devices for disposable lab-on-a-chip sensors

In this paper, we present an improved high-sensitivity approach for on-chip fluorescence-based measurements for disposable lab-on-a-chip (LOC). The approach is based on using an organic LED for excitation and an organic photodiode (OPD) as detector. By enhancing device integration with a custom interconnect, optical losses were minimized and the signal-to-noise ratio was increased. Using a bi-layer OPD improved detector responsivity 10 times over the conventional single heterojunction OPD. Finally, a lock-in amplifier was used instead of direct current measurements. Combining advantages of these improvements, a limit of detection of 10 nM was demonstrated, which is a 10-fold improvement over our previous reports and a 100-fold improvement over reports by others. We expect the developed approach to envisage numerous applications in point-of-care (POC) diagnostics and on-site environmental testing.