High-sensitivity, disposable lab-on-a-chip with thin-film organic electronics for fluorescence detection

Abstract

We report a high-sensitivity, disposable lab-on-a-chip with a thin-film organic light-emitting diode (OLED) excitation source and an organic photodiode (OPD) detector for on-chip fluorescence analysis. A NPB/Alq3 thin-film green OLED with an active area of 0.1 cm(2) was used as the excitation source, while a CuPC/C(60) thin-film OPD with 0.6 cm(2) active area was used as a photodetector. A novel cost-effective, cross-polarization scheme was used to filter out excitation light from a fluorescent dye emission spectrum. The excitation light from the OLED was linearly polarized and used to illuminate a microfluidic device containing a 1 microL volume of dye dissolved in ethanol. The detector was shielded by a second polarizer, oriented orthogonally to the excitation light, thus reducing the photocurrent due to excitation light leakage on the detector by approximately 25 dB. The fluorescence emission light, which is randomly polarized, is only attenuated by approximately 3 dB. Fluorescence signals from Rhodamine 6G (peak emission wavelength of 570 nm) and fluorescein (peak emission wavelength of 494 nm) dyes were measured in a dilution series in the microfluidic device with emission signals detected by the OPD. A limit-of-detection of 100 nM was demonstrated for Rhodamine 6G, and 10 microM for fluorescein. This suggests that an integrated microfluidic device, with an organic photodiode and LED excitation source and integrated polarizers, can be fabricated to realize a compact and economical lab-on-a-chip for point-of-care fluorescence assays.

Miniaturized Fluorometer Based on Total Internal Reflector and Condensing Mirror

“…These filters and polarizers, however, give some disadvantages in the loss of excitation light delivered to and fluorescence signal collected from the sample. A similar research was done by Pais et al (2008) [6] where they reported a disposable lab-on-a-chip (LOC) with an organic light-emitting diode (OLED) excitation source and an organic photodiode (OPD) detector for on-chip fluorescence analysis. They used a cross-polarization scheme to filter out excitation light from a fluorescent dye emission spectrum.…”

“…Many trials have been conducted to miniaturize the fluorescence detection system and at the same time improve its performance [5][6][7]. Gihan et al(2011) [5] devised a fluorescence immunoassay structured with a micro fluidic system that can handle liquid, where two orthogonally aligned linear polarizers are used to reduce the excitation light background that reaches the detector, and then pass filters help to discriminate the fluorescence signal from any excitation light background.…”

“…For over a decade an assay system based on fluorescence has been considered as one of the most commonly used and well established analytical methods, especially for applications such as high-throughput genomic and proteomic analysis, drug screening tests and real-time PCR (Polymer Chain Reaction) [1][2][3][4][5][6][7][8][9][10]. Recently, simplifying the fluorescence detection system has become more crucial because of the advent of micro total analysis systems (μTAS) many advantages in terms of speed, throughput and costs [11].…”

Organic Photodetectors in Analytical Applications

“…With this system, a LOD of 10 nM was obtained for several fluorescent dyes such as the common rhodamine 6G and fluorescein. Next, Banerjee et al replaced the halide excitation lamp with a green tris(8-hydroxyquinolinato) aluminum (Alq3)-based OLED [65][66][67], however, a higher 100 nM LOD was obtained with this on-chip design. The LOD was lowered to 10 nM by using an alternating CuPc/C60 bilayer OPD, which has a responsivity 10 fold better than that of a single layered heterojunction OPD [66].…”

OLED-based DNA biochip for Campylobacter spp. detection in poultry meat samples

“…Various authors (Yao et al, 2005;Hofmann et al, 2005;Pais et al, 2008;Ramuz et al, 2009;Lamprecht, 2010) demonstrated the utilization of an organic light emitting device (OLED) source as a fluorescence excitation source to produce a sensitive biochip.…”