Sensing Principle Oxygen Sensors
An optical oxygen sensor basically comprises of two important parts: An oxygen sensitive sensor indicator and a read-out device (oxygen meter).
The oxygen meter consist of a LED and photodiode which excites the oxygen sensitive indicator and detects its oxygen dependent luminescence emission. The excitation and emission light is transmitted via an optical fiber between the sensor indicator and the oxygen meter.
The working principle of the sensor layer is based on the quenching of the REDFLASH indicator luminescence caused by collision between oxygen molecules and the REDFLASH indicator. This indicator is immobilized in an polymer matrix and can be coated directly onto the optical fibers for fiber-optic sensors or onto transparent supports for contactless sensors.
The oxygen meter sinusoidally modulates red excitation light which results to phase-shifted sinusoidally modulated emission in the NIR. The emitted light of the sensor is dependent on the oxygen partial pressure and therefore can be used for oxygen determination.
The new REDFLASH technology is based on the unique oxygensensitive REDFLASH indicator showing excellent brightness. The indicators are excitable with red light (more precisely: orange-red at a wavelength of 610-630 nm) and show an oxygen-dependent luminescence in the near infrared (NIR, 760-790 nm). The REDFLASH technology impresses by its high precision, high reliability, low power consumption, low cross-sensitivity, and fast response times. The red light excitation significantly reduces interferences caused by autofluorescence and reduces stress in biological systems. The REDFLASH indicators show much higher luminescence brightness than competing products working with blue light excitation. Therefore, the duration of the red flash for a single oxygen measurement could be decreased from typically 100 ms to now typically 10 ms, significantly decreasing the light dose exposed to the measuring setup. Further, due to the excellent luminescence brightness of the REDFLASH indicator, the actual sensor matrix can be now prepared much thinner, leading to fast response times of the PyroScience oxygen sensors.
The product line includes various fibre-based and smart contactless sensor heads for compact PC-operated and stand-alone read-out devices for measurements in gas, water, aqueous and semi-solid samples. Sensor systems are also available for challenging measurements in organic solvents, microfluidics and high-throughput screenings.