A miniaturized fluorescence detection system with an integrated organic light emitting diode

The organic light emitting diode (OLED) is proposed as a novel source in the microchip because it has ideal merits (various wavelengths, thin-film structure and overall emitting) for the integration. In this paper, we fabricated finger-type PIN photodiodes for the fluorescence detection and an advanced microchip with an integrated OLED. The finger-type in the diode design extended the depletion region and its internal resistance was reduced about 32% than that of a rectangular-type. The photodiodes had 0.1 nA leakage current and 8,720 sensitivity (I_light/I_dark) at -1 V bias. The interference filter with 32 layers (SiO₂, TiO₂) was directly deposited on the photodiode. Deposited OLEDs increased the excitation efficiency and extremely simplified the integration process. The monolithically integrated microchip had a high sensitivity of 0.256 nA/μM and the LOD (limit of detection, S/N =2) of 0.01 μM.