Monolithic Integrated OLED–OPD Unit for Point-of-Need Nitrite Sensing

Abstract

In this study, we present a highly integrated design of organic optoelectronic devices for Point-of-Need (PON) nitrite (NO2−) measurement. The spectrophotometric investigation of nitrite concentration was performed utilizing the popular Griess reagent and a reflection-based photometric unit with an organic light emitting diode (OLED) and an organic photodetector (OPD). In this approach a nitrite concentration dependent amount of azo dye is formed, which absorbs light around ~540 nm. The organic devices are designed for sensitive detection of absorption changes caused by the presence of this azo dye without the need of a spectrometer. Using a green emitting TCTA:Ir(mppy)3 OLED (peaking at ~512 nm) and a DMQA:DCV3T OPD with a maximum sensitivity around 530 nm, we successfully demonstrated the operation of the OLED–OPD pair for nitrite sensing with a low limit of detection 46 µg/L (1.0 µM) and a linearity of 99%. The hybrid integration of an OLED and an OPD with 0.5 mm × 0.5 mm device sizes and a gap of 0.9 mm is a first step towards a highly compact, low cost and highly commercially viable PON analytic platform. To our knowledge, this is the first demonstration of a fully organic-semiconductor-based monolithic integrated platform for real-time PON photometric nitrite analysis.

Organic Electronics—Microfluidics/Lab on a Chip Integration in Analytical Applications

“…There have been significant recent advances for this promising approach [92,93], including potential future integration with the highly sensitive PPDs that were recently reported for sensitive (bio)chemical analyte detection [16].…”

“…Consequently, the photocurrent decreased. Reproduced from Titov et al [93] with permission from MDPI.…”

“…A 12.5 × 12.5 mm 2 8 OLED-OPD pair array on a common glass substrate with a reflection-type design was later developed for monitoring nitrites in solution (see Figure 14) [93], e.g., for toxicity testing of drinking water or aquaculture systems. Such a structure is suitable for integration with a microfluidic structure.…”

On-chip organic optoelectronic system for fluorescence detection

“…In particular, the two main components of the sensor, i.e. the light excitation source and the photodetector, are typically OLEDs and OPDs with customized shapes which are suitably integrated monolithically on a substrate 18 or stacked vertically to provide efficient and cooperative operation. [19][20][21][22][23] The third basic component is the sensing element, that is a luminescent compound whose optical properties change upon interaction with the analyte of interest.…”

Resonance‐Based Directional Light Emission from Organic Light‐Emitting Diodes: Comparing Integrated Nanopatterns and Color Conversion Waveguide Gratings

“…We have previously demonstrated a miniaturized optical sensing unit for point‐of‐need analysis comprising several pairs of OLED light sources and organic photodetectors on a single substrate. [ 7 ] Directional light emission toward the sensing spots may significantly increase the light utilization ratio and overall system sensitivity in the proposed side‐by‐side configuration. [ 8 ] In conventional sensing systems, additional components are typically used to adjust the optical path and focus light onto the sensing area.…”