OLED-based oxygen sensor

Fig. 3.7. Schematic of the structurally integrated OLED-based oxygen sensor (not to scale). The photodetector, a PMT or Si photodiode, is behind the OLED pixel array. The Ti02 nanoparticles, which are embedded in the dye PS-sensing film, act as a scattering medium, increasing the absorption of the EL by the dye...

In developing OLED-based oxygen and glucose sensors, oxygen-sensitive Ru, Pt, and Pd-based dyes, with large Stokes shifts (>100nm), were used. However, the rhodamine-based dye has a Stokes shift of only 20nm. As... 

Fig. 3.22. Structurally integrated OLED-based multianalyte sensor for oxygen, glucose, alcohol, and lactate. All of the sensing elements were based on a PSiPtOEP film, and the analytes were monitored via the PL decay time r of the PtOEP. The figure shows the intensity as a function of time (black lines) and the exponential fit (white lines). Measurements were conducted in air at 23°C...

The similarity of the responses and detection sensitivities for water and ethanol, despite the larger solubility of oxygen in ethanol ( 8 times higher at 25°C) [67], may indicate that the oxygen concentration in the PS host, which is in equilibrium with the DO, is comparable for both liquids. We note that the detection sensitivity of DO in water measured with the OLED-based sensors is among the highest reported for PtOEPiPS. 

Structurally integrated Alqj OLED-based sensors with PtOEP and PdOEP embedded in polystyrene (PS) yielded the highest sensitivities in monitoring gas-phase O2 and DO in water, ethanol, and toluene. " The gas-phase and DO sensors were evaluated extensively. In the gas-phase, the detection sensitivity is defined as Sg = Xo/x(100% O2) in solution, S o is defined as the ratio of x measured in a deoxygenated solution to that of an oxygen-saturated solution (i.e., a solution in equilibrium with a pure O2 atmosphere). 

To enhance the structural integration of the different components of the OLED-based sensor platform, efforts are underway to evaluate a fully integrated platform, where the PD is a p-i-n or n-i-p structure based on thin films of hydrogenated amorphous Si (a-Si H) and related materials, or nanocrystalline Si (nc-Si). These efforts focus on the oxygen sensors described above. 

This section reviews some recent developments on a multiple analyte sensor that is based on identical Alpg-based OLED pixels and monitors the serum analytes glucose, lactate, ethanol, and oxygen, which are of clinical, health, industrial, and environmental importance. These analytes were monitored sequentially or simultaneously comparable results were obtained using both approaches. 

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