Oxygen Microsensors

Sensor tip thinner than a hair (< 50 µm) Integrate & measure on-the-spot

Profiling of biofilms and sediments
Insertion in plant and animal tissue
Micro-respiration systems
Micro-invasive measurement in packages

Needle-type oxygen microsensors are miniaturized chemical optical oxygen sensors designed for all research and packaging applications where a small tip size (< 50 µm) and fast response time (t90 < 1s) are necessary. The optical oxygen microsensors are based on a 140 µm silica fiber and are available with two different sensor tip diameters, a < 50 µm tapered tip and a 140 µm flat-broken tip. The oxygen microsensors are mounted in different housings (needle-type housing, implantable) and offer a unique research tool for investigating systems where micro-invasive, small and robust sensors are needed.

Features

High spatial resolution (< 50 µm)
High temporal resolution (t90 < 1s)
Measurement range from 1 ppb up to 22.5 ppm dissolved oxygen
No consumption of oxygen
Signal independent of flow velocity
Measures oxygen in liquids as well as in gas phase

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Selected Probes

Needle-Type Oxygen Microsensors

Needle-Type O2 Microsensor - for normal measurement range and trace oxygen

Needle-type oxygen microsensors are perfectly suited for measuring oxygen distribution profiles in sediment and biofilms with a high spatial resolution of less than 50 µm. The oxygen-sensitive tip of an optical fiber is protected inside a stainless steel needle. This design is optimal for easy penetration of tissue, septum rubber or packaging materials. After penetration the sensor tip is extended for measurement.

Implantable Oxygen Microsensor

Implantable O2 Microsensor - for normal measurement range and trace oxygen

Implantable probes are the miniaturized fiber optic oxygen sensors designed for various customized applications. The tiny probe has a tip size of < 50 µm (TS) to 140 µm (TF) while the outer diameter ranges from 140 µm to 900 µm.
The microsensor tip is not mounted in any additional housing. The bare glass fiber tip can be mounted to your own housings, steel tubes and micro respirometer chambers etc. The small outer diameter even allows insertion into implantable Venlon-tubes. Moreover the microsensor can be deployed in sealed containers to measure the oxygen content directly.

The Smart Measurement Method

The light from the blue LED excites the sensor spot to emit fluorescence. If the sensor tip encounters an oxygen molecule, the excess energy is transferred to the oxygen molecule in a non-radiative transfer, decreasing or quenching the fluorescence signal. The degree of quenching correlates to the partial pressure of oxygen in the matrix, which is in dynamic equilibrium with oxygen in the sample. The decay time measurement is internally referenced.

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Examples for Applications

Oxygen Measurement in Headspace of Packaging

Oxygen Concentration of Small Headspace Packages

The determination of the oxygen content within packages or pharmaceutical vials is of essential importance to ensure both the filling quality and the long-term storage stability. With our micro-invasive needle-type oxygen microsensors we offer a simple tool to determine both the headspace and dissolved oxygen. The septum of the vial or package is pierced with the needle and the sensor is extended for measurement. As the measurement is made inside the package no error-prone sampling is necessary.

Tissue Engineering

Oxygen microsensors measure the oxygen content in various volume compartments of the tissue engineering constructs. To do so, hair-thin sensors are inserted into the constructs and the oxygen content is measured online. In this way, the oxygen partial pressure is measured with a high local resolution and correlated with the constructs tissue quality (composition of the extracellular matrix).

Profiling: Profile Measurements in Sediment and Tissue

Due to the extraordinary high local resolution (< 50 µm) our oxygen microsensors are ideally suited for recording microprofiles e.g. in sea-floor sediments, biofilms, plant physiology and human physiology. On the left you see oxygen profiles of a marine sediment populated with photosynthetically active microorganisms, measured in dark (closed symbols) and under strong illumination (open symbols). The measurement was performed simultaneously with an optical oxygen microsensor (blue) and a Clark-type micro-electrode (yellow). Both sensing tips have a distance of approx. 50 µm.

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