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Our Broad Product Range for Optical Measurements

Bring to light what's inside! PreSens Precision Sensing offers a variety of sensor probes, meters and complete systems for optical measurements of oxygen, pH, and carbon dioxide. More than 1,000 articles are on stock for fast delivery - including OEM components. In addition, PreSens is in the position to customize optical sensor components to meet your special application.

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How Optical Sensors Work

Core of the optical measurement technique is a fluorescent analyte-sensitive dye. This dye is embedded in a polymer matrix so it does not leach into the culture medium or sample. The indicator dye is excited by light of a certain wavelength and emits fluorescence in response. According to the amount of analyte molecules present the dye changes its fluorescence signal. This signal change can be measured with the respective electro-optical meter and translated in concentration values. To transfer excitation light to the optical sensor with the indicator dye and the sensor response back to the reader optical fibers are used. The indicator inside its polymer matrix can be coated on carrier materials or directly onto the distal end of an optical fiber, so different optical sensor designs can be realized.

The Right Optical Sensor for Each Application

The most versatile version of optical sensors are our sensor spots. Here the indicator dye is coated on a small round foil layer, with a diameter of usually 5 mm. These sensor spots for either O2, pH or carbon dioxide can be glued to the inner surface of transparent vessels or optical windows, where they are in contact with the sample. The optical sensors are then read out from the outside with the respective reader via polymer optical fiber. This contactless optical measurement principle can also be used for monitoring inside perfusion systems with flow-through cells where a miniaturized sensor is integrated. The separation of sensing component and meter makes optical sensors ideal tools for online monitoring in single-use culture vessels from mL up to L scale, or completely closed systems. No sampling is necessary. The sensors come irradiated and pre-calibrated, and different disposable or re-usable vessels with already integrated sensors are available.
The optical dipping probes have a similar design to the spots. There the spot is attached to the end of a steel tube with optical fiber inside. The probe is directly connected to the meter via this optical fiber. These probes are also available with exchangeable sensor caps, so it is even possible to switch to an optical sensor with another measurement range, and with port adapters for bioreactors. The oxygen probes are available in multiple autoclavable versions as well as in slender designs that are ideally suited for environmental applications.

For our different O2 & pH microsensor designs the indicator dye is coated to optical fibers with a tip size down to < 50 µm. We offer bare fiber microsensors, which are ideal for integration in customized housings or measurement set-ups, while needle-type housed microsensor integrated in a syringe cannula are ideally suited when hard surfaces have to be pierced to take optical measurements inside samples. As the optical fiber is so thin it is of course susceptible to breaking, but integrated in the steel cannula it can safely be pierced through septum rubber or packaging material. Specially designed and more robust Profiling Microsensors are also available, which are suited for insertion in semi-solid samples and have a mechanical interlock for exact vertical localization of the optical sensor tip inside the sample. Though not applicable for contactless optical measurements like sensor spots, these sensors make up for it with extremely high spatial resolution and fast response times. They can be applied with PreSens micromanipulator systems for most precise localization of the sensor tip inside the sample, and for profiling.

These are the basic sensor designs for optical measurement but many other solutions where sensors are integrated into special housings are available or can be manufactured, so you will find the most suitable sensor for your requirements. Just browse through our broad product range or use our Product Finder!