Spectrecology revolutionary O2 sensors

Oxygen Sensors — Fluorescence Quenching

Our O2 (molecular oxygen) sensors use the quenching of fluorescence by collision of molecular oxygen with a fluorophore that is trapped in an oxygen permeable sol gel or polymer. This technique is superior to polarographic electrodes in that O2 is not consumed. The sensing material can be coated on the tip of an optical fiber, or deposited as a thin film on flat substrates (patches and probe caps). We have a variety of sizes and shapes but they all work by the same principle. The NEOFOX “reader” is a phase fluorometer, which pulses a blue LED and measures the red fluorescence decay lifetime (tau) of the return signal. Neofox Sport and Neofox GTfluorescence quenching O2 sensor phase diagram There are three chemistries available:

  • ZERO-DRIFT AP for general purpose use in gases and aqueous based samples
  • MR hydrophobic sensor designed for fast response in gases
  • HCR for use in aggressive hydrocarbon solvents such as toluene, alcohol, acetone and aviation fuels.

Blog post – Response rates of sensors in fluids

Optical Oxygen Sensors are characterized by the chemistry, deposition process, and optical fiber probe design: *** Chemistries include AP, MR and HCR which are specific fluorophores in polystyrene or sol gel matrices. Deposition includes dip coating directly on an optical fiber, or spin coating flat substrates that are subsequently mounted to fibers as removable screw caps. Probe styles include:

  • F Style – single dip coated fibers in steel tubes or ferrules (1/16″, 1/8″, 1/4″ OD)
  • FT style – dip coated probes with an integrated thermistors (5/32″, 1/4″ OD) The thermistor wire length (TX) is available in 5′, 10′, 20′ or 30′ lengths. F style and FT style sensors require a bifurcated fiber bundle SEOX-BB-1000-X (x = 5′, 10′, 20′ or 30′) and a 21-02 splice bushing.
  • RCT style – Removable sensor cap sensors with embedded thermistors 1/4″, 3/8″ OD). Fibers and thermistor wire are integrated into the probe and come in a 5′ length. The length of the fibers and thermistor cables for any of the probes can be extended using SEOX-EXT-1000-X (X = 5′, 10′, 20′, 30′) extensions.
  • Patches – These spin coated substrates (acrylic and glass) can be mounted for remote interrogation by pointing a fiber probe at the back side of the substrate. This enables non-invasive monitoring of O2 inside of sealed containers. The patches are read with a bifurcated reflection/emission probe SEOX-BB-125
  • Sensor Chemistries Performance characteristics of the three pO2 sensor chemistries are compared in the table below.
Chemistries  AP  MR  HCR
 Response              fast  fast  fast
 Aqueous samples  excellent  excellent  no
 Gases  excellent  excellent  dry only
 Organic solvents  no  no  excellent
 Resistance to H20 vapor  excellent  excellent  no
 Calibration Stability  excellent  excellent  excellent
 Stability in temperature extremes  medium  good  good
 Mechanical Stability  good  excellent  excellent

Probe style refers to the size and construction of the optical fibers, mechanical construction, sensor material deposition and other features such as built in temperature sensors. Most probe styles can be made with any of the chemistries. Custom probe styles are also available.

Fiber Optic O2 probes – F series

F series probes are 1000um optical fibers in 7″ stainless steel ferrules. They have an SMA on one end and the chemistry dip coated to the angled sensor face. These are the simplest probes, and are generally used in controlled temperature environments, or with the external thermistor. F style sensors can be made smaller diameter than the other styles. On request we can make them integrated into needles for puncturing media, or in 1/32″ OD probes. SEOX F series family

SEOX-F116-A O2 Fiber Probe, 1000um, 1/16″ OD x 7″ A coating
SEOX-F116-HCR O2 Fiber Probe, 1000um,  1/16″ OD x 7″ HCR coating for hydrocarbons
SEOX-F125-A O2 Fiber Probe, 1000um, 1/8″ OD x 7″  A coating
SEOX-F125-HCR O2 Fiber Probe, 1000um,  1/8″ OD x 7″ HCR coating for hydrocarbons
SEOX-F125-S-A O2 Fiber Probe, 1000um, 1/8″ OD x 2.5″ A coating
SEOX-F125-S-HCR O2 Fiber Probe, 1000um,  1/8″ OD x 2.5″ long HCR for hydrocarbons
SEOX-F250-A O2 Fiber Probe, 1/4″ OD x 7″  55bar pressure rated & A coating
SEOX-F250-HCR O2 Fiber Probe, 1/4″ OD x 7″ 55bar pressure rated & HCR coating
Buy F Style O2 Probes Online

Fiber Optic O2 with thermistor – FT Series

FT series probes are 1000um optical fibers in 7″ stainless steel ferrules with a thermistor integrated into the probe body. These probes are available in 5/32″ and 1/4″ sizes. They are easier to use because of the embedded thermistor. Standard models include: Dip coated optical oxygen sensors with thermistor have zero drift

SEOX-FT156-A-T10 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & AP, 10′ thermistor lead
SEOX-FT156-A-T20 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & AP, 20′ thermistor lead
SEOX-FT156-A-T30 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & AP, 30′ thermistor lead
SEOX-FT156-A-T5 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & AP, 5′ thermistor lead
SEOX-FT156-HCR-T10 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & HCR, 10′ thermistor lead
SEOX-FT156-HCR-T20 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & HCR, 20′ thermistor lead
SEOX-FT156-HCR-T30 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & HCR, 30′ thermistor lead
SEOX-FT156-HCR-T5 O2 Fiber Probe, 5/32″ OD, 7″ long, SS, thermistor, SMA & HCR, 5′ thermistor lead
SEOX-FT250-A-T10 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & AP, 10′ thermistor lead
SEOX-FT250-A-T20 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & AP, 20′ thermistor lead
SEOX-FT250-A-T30 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & AP, 30′ thermistor lead
SEOX-FT250-A-T5 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & AP, 5′ thermistor lead
SEOX-FT250-HCR-T10 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & HCR, 10′ thermistor lead
SEOX-FT250-HCR-T20 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & HCR, 20′ thermistor lead
SEOX-FT250-HCR-T30 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & HCR, 30′ thermistor lead
SEOX-FT250-HCR-T5 O2 Fiber Probe, 1/4″ OD, 7″ long, SS, thermistor, SMA & HCR, 5′ thermistor lead
SEOX-FT375-A-T10 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & AP, 10′ thermistor lead
SEOX-FT375-A-T20 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & AP, 20′ thermistor lead
SEOX-FT375-A-T30 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & AP, 30′ thermistor lead
SEOX-FT375-A-T5 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & AP, 5′ thermistor lead
SEOX-FT375-HCR-T10 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & HCR, 10′ thermistor lead
SEOX-FT375-HCR-T20 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & HCR, 20′ thermistor lead
SEOX-FT375-HCR-T30 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & HCR, 30′ thermistor lead
SEOX-FT375-HCR-T5 O2 Fiber Probe, 3/8″ OD, 7″ long, SS, thermistor, SMA & HCR, 5′ thermistor lead
Buy FT Style O2 Sensors Online!

Removable Sensor Cap with Thermistor – RCT Series

SEOX FT156 assembly and tip 400 zerodroft optical O2 RCT Series Probes   RCT series probes have a thermistor embedded in the probe body, to provide temperature compensation. Fibers are also integral parts of the probe. The standard length of the thermistor cable and fibers is 5′. Extensions can be added to elongate the probe cables. RCT probes have removable sensor caps. These are sensor discs permanently mounted in a threaded cap. These probes have the advantage that the user can change chemistries just by changing caps. RCT optical O2 sensor with removeable sensor cap  

SEOX-RCT250-A Screw cap O2 Sensor, 1/4″ OD, 7″ long, SS, thermistor,SMA, & AP chem
SEOX-RCT250-HCR Screw cap O2 Sensor, 1/4″ OD, 7″ long, SS, thermistor, SMA & HCR chemistry
SEOX-RCT250-MR Screw cap O2 Sensor, 1/4″ OD, 7″ long, SS, thermistor, SMA & MR chemistry
SEOX-RCT375-A Screw cap O2 Sensor, 3/8″ OD, 7″ long, SS, thermistor, SMA &  AP cap
SEOX-RCT375-HCR Screw Cap O2 Sensor, 3/8″ OD, 7″ long, SS, thermistor, SMA & HCR cap
SEOX-RCT375-MR Screw Cap O2 Sensor, 3/8″ OD, 7″ long, SS, thermistor, SMA & MR cap
Buy RCT Style O2 Sensors Online!

Performance Specifications for all probe styles, by probe chemistry 

AP formulation Polystyrene matrix HCR formulation Sol Gel matrix MR formulation Sol Gel matrix
Response Rate T90 = 3 sec T90 = 1 sec T90 = 1 sec
Dynamic Range (gas) 0 – 760 mmHg0 – 100% (at 1 atm) 0 – 760 mmHg0 – 100% (at 1 atm) 0 – 760 mmHg0 – 100% (at 1 atm)
Dynamic range (DO) 0 – 40 ppm in H2O 0 – 40 ppm in H2O 0 – 40 ppm in H2O
Resolution (gas) 0.04 mmHg0.005% (at 1 atm) 0.4 mmHg0.05% (at 1 atm) 0.4 mmHg0.05% (at 1 atm)
Resolution (DO) 0.002 ppm in H2O 0.002 ppm in H2O 0.002 ppm in H2O
Accuracy 5% of reading 5% of reading 5% of reading
LDL (gas) 0.04 mmHg0.005% (at 1 atm) 0.4 mmHg0.05% (at 1 atm) 0.4 mmHg0.05% (at 1 atm)
LDL (DO) 0.002 ppm in H2O 0.002 ppm in H2O 0.002 ppm in H2O
Drift rate No measureable long term drift, continuous operation 0.0001 % /hr in gas 0.0001 % /hr in gas
Sensor Operating Temperature -50 to 100C -50 to 200C -50 to 200C
Useful Lifetime 3 years 3 years 3 years
Compatibility General purpose gases and aqueous solutions Organic solvents General purpose gases and aqueous liquids
Water Vapor Interference no yes no
Formats Dip coated fibersSpin coated patches & probes Dip coated fibersSpin coated patches & probes Dip coated fibersSpin coated patches & probes
Review Best general purpose probe, longer fluorescence decay yields more resolution, zero drift means stable calibrations Used for organic solvents and gases with organic vapors.  This sensor does respond to water vapor as well as O2 General purpose but with faster response rate than AP chemistry. Does exhibit long term photo-bleaching drift and has less resolution.

 

  • Dissolved Oxygen DO Sensors Any of the sensor styles can be used for dissolved oxygen. AP chemistry is especially good for DO measurement in water based media. The reflective white overcoat improves the signal strength and protects the probe from dirt, debris and fouling found in natural waters. For field work our portable NEOFOX-SPORT is ideal.
  • Process and Laboratory Oxygen Sensors O2 Probe bodies are made of stainless steel tubes to encase the optical fibers. These probes can be inserted into compression style tube fittings for introduction into pipes are reactors, or they can be dipped into open containers of liquids. Pressure ratings for the F series probes are 55 bar. Probes can be made with custom lengths, diameters and flanges. pO2 Sensors The MR sensor chemistry is specially formulated for fast response and moisture resistance for measuring pO2 in gas streams. It can withstand high temperatures and has a response rate < 1sec.
  • Fuel and Hydrocarbon pO2 sensors HCR chemistry is designed to work in aggressive organic solvents — acetone, toluene, Jet-A, kerosene. It is available on any of our style probes.  In patch format glass substrate is required.
  • SEOX Sensor Patches and Discs  Sensor discs are clear acrylic coated with AP sensing chemistry or glass with HCR coating on the front side. They can be glued in place and read by pointing a a bifurcated probe at the back side of the disc. If they are mounted on a clear container wall, you can read pO2 in the inside of the container from the outside, without disturbing the sample. This is very useful for measuring respiration, monitoring O2 in sterile environments and bioreactors, and other sealed systems such as glove boxes, incubators or products packaged in modified air. The drawing below shows an installation with a RCT probe installed in a compression fitting put through the container wall (lower), and an SEOX patch being read through the wall of the container with a bifurcated fiber probe. Fiber Assemblies Used with Sensors SEOX-BB-1000 Bifurcated borosilicate fiber, SMA, for 1000um sensors SEOX-BB-125 Bifurcated bundle with 1/8″ ferrule for reading sensor discs.

Open a price list for all Zero drift sensors and accessoriesSEOX Price List 03_18_15 Buy O2 Sensor Patches Online!

O2 sensor patches for non-invasive oxygen measurementsnon invasive pO2 measurements for respiration BOD COD