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Retractable Needle-Type Oxygen Sensors

  • Optical oxygen sensors
  • Microsensors & Minisensors
  • Original REDFLASH technology
  • Works in gas (%O2) and in liquids (DO)
  • No oxygen consumption
  • Response times down to <0.3 s
  • Sensor tip retractable in needle
  • >3 years shelf time
  • Stainless steel
  • Optional underwater / deep sea versions
  • Optional trace oxygen versions

These fiber-optic oxygen sensors offer unprecedented fast response times (down to <<1s) combined with high spatial resolution (down to ~50µm tip diameter). They are based on optical detection principles (REDFLASH technology). They assure very precise measurements, as they do not consume any oxygen and show no stirring sensitivity.


Furthermore, they come with an extremely long shelf time of >3 years. The actual sensor tip is surrounded by a 40 mm long syringe needle. The unique 4-step sliding mechanism allows the sensor tip to be moved out of the protective needle at three different positions. In the fourth "parking position", the sensor tip is completely retracted into the needle giving maximum protection while handling the sensor. The "parking position" is also useful for penetrating packages or a septum without damaging the sensor tip. The complete sensor is resistant to corrosive environments (e.g. seawater), as all metallic parts are made of stainless steel.

Trace range versions. Special trace range versions are available for high precision measurements close to 0%O2. They offer about 5x higher resolution compared to the normal range oxygen sensors. The recommended measuring range is 0-10% O2. However, calibration at ambient air (21% O2) is possible, ensuring a straightforward calibration without the need of special calibration standards.


Compatible oxygen meters

FireStingO2 (FSO2-x)
FireStingGO2 (FSGO2)
FireStingO2-Mini (FSO2-MINI-ST)
FireStingO2-SubPort (FSO2-SUBPORT) for sensors with underwater connectors (option -SUB)

Normal Range Versions

Item No. Description
(Needle / Tip Diameter)
Time (s)**
in EU*
OXR50 Retractable Oxygen Microsensor
(0.5mm / ca. 40-60µm)
<2 s (liquid)
<1 s (gas)
230 €
OXR50-HS Retractable Oxygen Microsensor
(0.5mm / ca. 40-60µm), high speed
<0.8s (liquid)
<0.8s (gas)
260 €
OXR50-UHS Retractable Oxygen Microsensor
(0.5mm / ca. 40-60µm), ultra high speed
<0.3s (liquid)
<0.3s (gas)
290 €
OXR230 Retractable Oxygen Minisensor
(0.5mm / 230 µm)
<2 s (liquid)
<1 s (gas)
290 €
OXR430 Retractable Oxygen Minisensor
(1.1mm / 430 µm)
<2 s (liquid)
<1 s (gas)
290 €
OXR430-HS Retractable Oxygen Minisensor
(1.1mm / 430 µm), high speed
<0.8 s (liquid)
<0.8 s (gas)
320 €
OXR430-UHS Retractable Oxygen Minisensor
(1.1mm / 430 µm), ultra high speed
<0.3 s (liquid)
<0.3 s (gas)
350 €
OXR50-OI Retractable Oxygen Microsensor
(0.5mm / ca.40-60µm), optical isolation
<3 s (liquid)
<2 s (gas)
290 €
OXR230-OI Retractable Oxygen Minisensor
(0.5mm / 230 µm), optical isolation
<10 s (liquid)
<4 s (gas)
350 €
OXR430-OI Retractable Oxygen Minisensor
(1.1mm / 430 µm), optical isolation
<10 s (liquid)
<6 s (gas)
350 €

Trace Range Versions

Item No. Description
(Needle / Tip Diameter)
Time (s)**
in EU*
TROXR430 Retractable Trace Oxygen Minisensor
(1.1mm / 430 µm)
<15 s (liquid)
<2 s (gas)
290 €

* Only EU-Prices shown. Contact us for pricing outside EU. Not for resale.

** Typical response times for 90% signal change (T90).
     For liquids: measured for the transition from air into a stirred solution of 1% Na2SO3.


Item No. Extension Description Extra Charge
-CL4 Cable length of ca. 4m (instead of standard 2m cable length) add 30 €
-OI Black optical isolation on the very sensor tip. Recommended for applications with intense background illumination (e.g. direct sun light) or for media with strong luminescent properties (e.g. very dense algae cultures). Refer to the tables above for available sensor versions. see above
-HS High speed. Selected sensors with fast response times. Refer to the tables above for available sensor versions. see above
-UHS Ultra high speed. Selected sensors with very fast response times. Refer to the tables above for available sensor versions. see above
-SUB Underwater connector (instead of standard ST-connector) needed for applications with the underwater OEM-solution FireStingO2-SubPort. Contact us for available sensor versions. no extra charge
-CLx Custom cable length of x meter (max. 20m) on request
-Nx/y Custom needle types (x mm in diameter, y mm in length) surrounding the sensor tip. Contact us for possible combinations. on request

: Item no. OXR430-HS-CL4-SUB designates a high speed minisensor with 4m cable and with underwater connector.

Tip Geometries

True to scale drawings with syringe needle (grey), optical fiber (pink), and oxygen sensitive REDFLASH dye (green)


Given for 2-point calibrated oxygen sensors at 1013mbar absolute pressure.

Normal range versions hPa %O2 %air sat. mg/L
Optimum measuring range 0-500 0-50 0-250 0-23
Maximum measuring range (not specified) 0-1000 0-100 0-500 0-45
Detection limit 0.2 0.02 0.1 0.01
Resolution at 1% O2 0.1 0.01 0.05 0.005
Resolution at 20% O2 0.5 0.05 0.25 0.025
Accuracy at 1% O2 ±0.2 ±0.02 ±0.1 ±0.01
Accuracy at 20% O2 ±2 ±0.2 ±1 ±0.1
Trace range versions hPa %O2 %air sat. mg/L
Optimum measuring range 0-100 0-10 0-50 0-5
Maximum measuring range (not specified) 0-210 0-21 0-100 0-9
Detection limit 0.05 0.005 0.02 0.002
Resolution at 0.2% O2 0.02 0.002 0.01 0.001
Accuracy at 0.2% O2 typ. 2% of reading, but not better than 0.01%O2
All versions
Temperature range 0 to 50°C (specified), -20 to 70°C (not specified)
Minimum lifetime 1,000,000 data points
Application areas Laboratory, industry, research. Not for medical or any other safety-critical applications. Not for application in humans or in food intended for human consumption.
Compatibility Gas-phase, aqueous solutions, ethanol, methanol, isopropanol (note: the optional optical isolation (-OI) is not compatible to ethanol, methanol, isopropanol)
Cross sensitivity Other organic solvents, chlorine
No cross sensitivity pH 1-14, CH4, CO2, H2S, any ionic species
Sterilization Ethylene oxide (EtO), 70% ethanol, 70% isopropanol
Cleaning 3 % H2O2, ethanol, soap solution
Storage time >3 years in darkness at room temperature
Calibration Single point, two point calibration
Dimensions Total length ca. 170 mm (from needle tip to cable), shaft diameter 8 mm
Needle length 40 mm
Tip positions Sensor tip adjustable at -6, 0, 6, 12 mm relative to needle tip
Connector ST-plug (optional: underwater connector)
Cable length 2m or 4m (standard), optional up to 20m