On-chip organic optoelectronic system for fluorescence detection

Conventional fluorescence sensing, despite its high sensitivity, is poorly suited for point-of-need applications due to the bulkiness and cost constraints of standard components. An urgent market demand exists for integrated, portable, and high-performance solutions. Here, an efficient and miniaturized fluorescence sensor is demonstrated by innovative integration on a single substrate of organic optoelectronic devices, such as an organic photodiode and an organic light-emitting diode, with a polymeric distributed Bragg reflector. Optical modeling of the 3D layout of integration of the three all-organic components allows maximizing the optical efficiency of the sensing system, which outperforms that of state-of-the-art miniaturized fluorescence sensors by two orders of magnitude. Accordingly, fluorescence signals from microfluidic volumes of Rhodamine 700 are detected by the sensor over a wide range of dye concentrations, ranging from 10−3 M to 10−6 M. The optimized exploitation of the angular dependence of the distributed Bragg reflector filter characteristics provides a remarkable reduction of the undesired optical signal of excitation. As a result, a significant increase of the signal-to-noise ratio allows for halving the detection limit of Rhodamine 700 down to 9.2 μM, thus demonstrating the possible implementation of such innovative integrated detection scheme for biodiagnostics.