Ozone Sensors
Select O₃ sensors for ambient air quality, worker safety, ozone generators, disinfection equipment, sterilization systems and high-concentration process monitoring. Compare low-level electrochemical sensors, oxidant channels, conditioned modules and high-range MOS or electrochemical options.
Choose the ozone sensor around the concentration and job
Ozone is used deliberately in disinfection and industrial treatment, while low-level O₃ is also an air pollutant and occupational hazard. These applications need different sensor ranges and gas paths.
ppb to 1 ppm
Use a stable low-level electrochemical or oxidant-channel architecture with temperature correction and NO₂ separation.
- Urban / roadside monitoring
- Environmental stations
0–1 / 2 / 5 ppm
Portable and fixed detectors need reliable low-ppm response and clear cross-sensitivity data.
- Ozone-generator rooms
- Water-treatment / sterilization areas
0–10 / 20 ppm
Useful for cabinet leakage, chamber residual ozone and exhaust verification after treatment cycles.
- Cabinets and rooms
- Surface / air sterilization systems
100–1000+ ppm
Generator output and process gas need extended-range electrochemical or semiconductor sensing.
- Generator output
- Ozone process control
UART module
Use a conditioned module when the controller needs concentration data instead of raw electrochemical current.
- Portable detector
- Smart appliance / disinfection equipment
MOS / semiconductor
Useful when high range and simple circuitry matter more than electrochemical selectivity.
- Heater power required
- Strong oxidants can cross-respond
Electrochemical and MOS ozone sensors solve different problems
O₃ is a strong oxidizing gas. Electrochemical cells are widely used for quantitative low-level measurement, while metal-oxide sensors provide a wider, lower-cost route for some high-concentration and embedded products.
3-electrode EC
Produces a current related to ozone concentration with low sensing-element power.
Best fit: worker safety, disinfection and process control.4-electrode oxidant EC
An auxiliary electrode improves baseline control in ppb-level air-quality work.
Best fit: ambient and roadside networks.Conditioned EC module
Adds signal conditioning, temperature compensation and UART or analog output.
Best fit: fast OEM integration.MOS semiconductor
A heated oxide changes resistance in ozone and other oxidants.
Best fit: wide-range, cost-sensitive embedded designs.Ozone sensors for ambient, safety, disinfection and process designs
The shortlist mixes low-level safety sensors, ppb oxidant channels, conditioned OEM modules and extended-range process products.
| OEM need | Manufacturer | Model | Type | Published range | Key engineering point | Official source |
|---|---|---|---|---|---|---|
| Low-level digital ozone | Winsen | ZE25A-O₃ | Electrochemical module | 0–2 ppm | 0.001 ppm resolution, UART, T90 ≤90 s, 2-year published life; intended for portable, air-quality and disinfection equipment. | Official ↗ |
| Fast low-range safety | SENKO | SB-4O3-1 | Electrochemical | 0–1 ppm max overload 5 ppm | T90 <25 s, <0.02 ppm typical resolution and >24-month expected life. | Official ↗ |
| General low-ppm safety / process | Alphasense | O3-AH | 3-electrode electrochemical | 0–20 ppm | High-sensitivity A-Series ozone sensor, T90 <80 s, used for worker protection, ozone generation and environmental monitoring. | Official ↗ |
| PPB ambient oxidant channel | Alphasense | OX-B431 | 4-electrode oxidant EC | 0–20 ppm O₃ + 0–20 ppm NO₂ | Combined O₃ + NO₂ channel for fixed air-quality networks; pair with filtered NO2-B43F to separate the two gases. | Official ↗ |
| Compact portable ambient oxidant | Alphasense | OX-A431 | 4-electrode oxidant EC | 0–20 ppm O₃ + 0–20 ppm NO₂ | PPB-level A-Series oxidant sensor, typically paired with NO2-A43F for differential O₃ calculation. | Official ↗ |
| Raw 20 mm ozone cell | Winsen | ME3-O₃ | Electrochemical | 0–10 ppm | 0.05 ppm resolution, T90 ≤120 s and 2-year anticipated life for industrial and environmental use. | Official ↗ |
| High-range raw electrochemical | Winsen | ME2-O₃ | Electrochemical | 0–10 / 100 ppm max 200 ppm | ≤0.02 ppm published resolution and T90 ≤120 s; wider range than typical room-safety cells. | Official ↗ |
| High-range digital module | Winsen | ZE14-O₃ | Electrochemical module | 0–100 ppm | UART, 0.1 ppm resolution, T90 ≤90 s and -10 to 65°C operating range. | Official ↗ |
| High-range process EC | Membrapor | O3/C-200 | 3-electrode electrochemical | 0–200 ppm | <0.2 ppm resolution and T80 <60 s; intended for safety and process control. | Datasheet ↗ |
| Very high-range semiconductor | Winsen | MQ131-H | MOS semiconductor | 10–1000 ppm | ≤950 mW heater; broad response to strong oxidants including O₃, Cl₂ and NO₂. | Official ↗ |
Published values are component or module specifications. Confirm the latest datasheet, cross-sensitivity, stabilization requirements and finished-instrument performance before design freeze.
O₃ sensor priorities change sharply with concentration
Ambient air-quality monitoring
At ppb concentration, NO₂ separation, baseline stability and temperature correction are more important than having a very wide full-scale range.
| Route | Range | Strength | Watch point |
|---|---|---|---|
| Alphasense OX-B431 + filtered NO₂ | 0–20 ppm oxidants | PPB outdoor network architecture with separate O₃ / NO₂ calculation. | Both channels need zero and temperature correction. |
| Alphasense OX-A431 + filtered NO₂ | 0–20 ppm oxidants | More compact A-Series route for portable or distributed AQ nodes. | Same differential-channel requirements. |
| Winsen ZE25A-O₃ | 0–2 ppm | Direct digital ozone module with 0.001 ppm published resolution. | NO₂ and Cl₂ are listed interferents; validate the ambient gas mix. |
Worker safety and ozone-generator rooms
Low-range room monitoring should detect leakage well below process output concentration and should not saturate during a credible release.
| Product | Range | Response | Engineering point |
|---|---|---|---|
| SENKO SB-4O3-1 | 0–1 ppm | T90 <25 s | Fast low-range route for portable and fixed safety. |
| Winsen ZE25A-O₃ | 0–2 ppm | T90 ≤90 s | Digital low-level module for portable / fixed / disinfection equipment. |
| Alphasense O3-AH | 0–20 ppm | T90 <80 s | Wider-range EC route for worker safety near ozone generation and treatment systems. |
Disinfection equipment and sterilization chambers
Cabinets and rooms often need both process-cycle confirmation and a safe-residual check before occupants or products are exposed.
| Measurement point | Typical need | Suitable route |
|---|---|---|
| Room / cabinet leakage | Low ppm | ZE25A-O₃, SB-4O3-1, O3-AH class. |
| Chamber residual after cycle | Low ppm with stable zero | Conditioned electrochemical module. |
| Process gas / generator feed | Tens to hundreds of ppm or more | ME2-O₃, ZE14-O₃, Membrapor high-range or other process analyzer. |
High-concentration ozone process gas
Generator output and process ozone should be measured with a range designed for sustained high concentration rather than repeatedly overloading a low-ppm safety sensor.
| Product / family | Range class | Engineering point | Official source |
|---|---|---|---|
| Winsen ME2-O₃ | 0–100 ppm option | Raw electrochemical route with max 200 ppm published concentration. | Official ↗ |
| Winsen ZE14-O₃ | 0–100 ppm | Conditioned UART module for disinfection and smart equipment. | Official ↗ |
| Membrapor O3/C-200 | 0–200 ppm | High-range 3-electrode EC for safety / process control. | Datasheet ↗ |
| Winsen MQ131-H | 10–1000 ppm | Very wide MOS range with strong oxidant response and heater-based operation. | Official ↗ |
O₃ and NO₂ can look similar to an electrochemical oxidant sensor
Ozone and nitrogen dioxide are both strong oxidants. Some air-quality sensors deliberately measure the combined oxidant response, while a filtered NO₂ channel is used to separate the two gases.
Dedicated O₃ sensor
Designed around ozone response but still needs a cross-sensitivity review for NO₂, Cl₂ and other oxidants.
Example: Alphasense O3-AH.OX channel
Measures O₃ + NO₂ together at ppb level.
Example: OX-A431 / OX-B431.Filtered NO₂ channel
Measures NO₂ while rejecting ozone.
Pair with NO2-A43F / NO2-B43F.Differential ozone
O₃ is calculated from the corrected oxidant channel minus the corrected filtered NO₂ channel.
Useful for ambient AQ nodes.PPB ozone measurement is mainly a selectivity and zero-stability problem
Outdoor ozone changes with sunlight, NOx chemistry, weather and time of day. A low-noise sensor is useful only when the station also controls cross-sensitivity, baseline drift and enclosure airflow.
NO₂ separation
Use a dedicated low-cross-response O₃ sensor or a differential oxidant / filtered-NO₂ architecture.
- Validate both channels across temperature.
- Do not subtract uncorrected raw voltages.
Temperature & zero
Ambient ppb signals can be smaller than environmental zero movement.
- Use auxiliary-electrode or module compensation.
- Evaluate day/night and seasonal temperature cycles.
Station airflow
The enclosure must admit representative air without allowing rain, dust or condensation to damage the sensor.
- Measure complete station response time.
- Use co-location to reveal field bias.
Separate leak monitoring from process ozone measurement
A generator room may need sub-ppm worker protection while the generator or chamber contains ozone at tens, hundreds or more ppm. Treat these as separate measurement channels.
Room / worker protection
- Use a low-range electrochemical O₃ sensor.
- Place sensors around credible release points and occupied airflow.
- Use ventilation interlocks and alarms according to the equipment / site design.
- Verify safe residual concentration before re-entry where required.
Generator / process measurement
- Use 100 ppm, 200 ppm or wider-range sensing where process concentration requires it.
- Keep process gas within the sensor temperature and humidity limits.
- Avoid exposing a 1–2 ppm room-safety sensor continuously to generator-output concentration.
- Use a dedicated analyzer when accuracy or concentration exceeds electrochemical / MOS capability.
Electrochemical and MOS routes both extend into process concentrations
High concentration does not automatically mean MOS. Extended-range electrochemical ozone cells are available into the hundreds or thousands of ppm, while MOS offers a broad and economical route with different selectivity and power requirements.
Extended-range electrochemical
- ME2-O₃: 0–10 / 100 ppm options.
- ZE14-O₃: 0–100 ppm conditioned module.
- Membrapor compact family: O3/C-100, -200, -1000 and -5000 product variants.
- Better suited where quantitative O₃ is still required.
MOS semiconductor
- MQ131-H: 10–1000 ppm.
- Heater consumption ≤950 mW.
- Simple resistance-based interface.
- Cross-response to Cl₂ / NO₂ and other strong oxidants must be accepted or compensated.
Ozone gas sensors do not measure dissolved ozone in water
Water treatment creates two different ozone measurements: gaseous O₃ around generators, contactors and off-gas systems, and dissolved ozone in the treated water. This page covers the gas phase.
| Measurement | Target | Typical unit | Sensor format | Use |
|---|---|---|---|---|
| Ozone gas | O₃ in air / process gas | ppb / ppm | Electrochemical, MOS or gas analyzer | Leak, room safety, off-gas, generator/process monitoring |
| Dissolved ozone | O₃ in water | mg/L or ppm in liquid | Water-quality probe / analyzer | Water-treatment residual and process control |
Ozone can be lost before it reaches the sensor
O₃ is highly reactive. Long tubing, unsuitable materials, contaminated surfaces and some filters can consume ozone and make the detector read low or respond slowly.
Keep it short
Minimize remote sample-line length where possible.
Use compatible materials
Validate tubing and fittings for ozone service.
Avoid dirty surfaces
Organic contamination can rapidly destroy O₃ in the sample path.
Control moisture
Prevent condensation on filters and sensor inlets.
Calibrate through the path
Verify the detector using the same gas-delivery route where practical.
Winsen ozone sensors and modules by range
Winsen covers low-level electrochemical modules, raw electrochemical cells, a general configurable module and a high-concentration semiconductor route.
ZE25A-O₃
0–2 ppm, 0.001 ppm resolution, UART, T90 ≤90 s and 2-year published life. Suitable for portable O₃ detectors, air-quality devices and disinfection equipment.
ZE03-O₃
Current ZE03 manual lists O₃ 0–10 ppm, 0.1 ppm resolution and T90 ≤120 s, with UART plus analog voltage output.
ME3-O₃
0–10 ppm measurement range, 50 ppm maximum detecting concentration, 0.05 ppm resolution and T90 ≤120 s.
ME2-O₃
0–10 / 100 ppm range options, maximum 200 ppm, ≤0.02 ppm published resolution and T90 ≤120 s.
ZE14-O₃
0–100 ppm, 0.1 ppm resolution, UART, ≤90 s response and 2-year published life. Intended for ozone disinfection and smart equipment.
MQ131-H
10–1000 ppm semiconductor ozone sensor with ≤950 mW heater consumption. It also responds to strong oxidizing gases including Cl₂ and NO₂.
Other ozone sensor product ranges
These manufacturers publish O₃ sensors for worker safety, ambient air quality, industrial ozone generation and process control.
Alphasense
Dedicated O₃ and combined O₃/NO₂ oxidant sensors for safety and ppb air-quality monitoring.
SENKO
Fast 0–1 ppm electrochemical ozone sensor for portable and fixed detectors.
Membrapor
Compact O₃ sensors from highly sensitive 5 ppm products through 5000 ppm process ranges.
Honeywell Sensoric
Current Sensoric portfolio includes O3 3E 1F and O3 3E 1 electrochemical ozone sensors.
Submit an O₃ sensor
Manufacturers can provide an official product page and current datasheet for inclusion.
Ozone calibration must include the real gas path
Because ozone is reactive, the calibration source can be correct while the concentration at the sensor is lower. Verify the tubing, fittings, enclosure and stabilization time as part of calibration.
Bump / response check
Confirms that ozone reaches the detector and that the channel responds in the expected direction and time.
Span calibration
Uses a traceable O₃ source or calibration system appropriate to the range. Follow the instrument's specified flow and stabilization method.
Field verification
For ambient ppb devices, co-location with a reference-grade monitor helps identify ozone/NO₂ separation error, drift and environmental bias.
Ozone sensor questions
What ozone sensor range is typical for worker safety?
Low-ppm electrochemical sensors are commonly used for room, portable and fixed ozone-safety monitoring. The correct range should cover the expected alarm region and credible leak level while preserving enough low-level resolution for the application.
What is the difference between an ozone sensor and an oxidant sensor?
A dedicated ozone sensor is designed around O3 response, while an oxidant sensor may respond to both ozone and nitrogen dioxide. In ambient monitoring, an oxidant channel can be paired with a filtered NO2 channel to separate O3 and NO2.
Can the same ozone sensor measure room leaks and ozone-generator output?
Usually not optimally. Room safety may require ppb or low-ppm sensitivity, while generator output or process gas can reach tens, hundreds or thousands of ppm. Use a range designed for the actual concentration.
Why is NO₂ interference important for O₃ sensors?
O3 and NO2 are both oxidizing gases. Many electrochemical and metal-oxide ozone sensors respond to NO2 as well. Use a dedicated sensor with known cross-sensitivity or a dual-channel oxidant/NO2 architecture when both gases can be present.
When should I choose an electrochemical ozone sensor instead of MOS?
Choose electrochemical sensing when quantitative low-level ozone, low sensing power and better oxidant selectivity are priorities. MOS can be useful for wider-range and cost-sensitive designs but requires heater power, stabilization and application-specific calibration.
Does this page cover dissolved ozone in water?
No. This page covers gaseous ozone in air or process gas. Dissolved ozone in water requires a water-quality probe or analyzer designed for liquid measurement.
How should ozone-generator rooms be monitored?
Use one or more low-range gas sensors in locations that represent possible leaks and occupied air. Generator output concentration should be measured separately with a range suited to the process. Follow the equipment manufacturer's ventilation and installation requirements.
How should ozone sensors be calibrated?
Use certified ozone calibration equipment or a traceable ozone source appropriate to the range. Validate the complete detector gas path, including filters, tubing and enclosure diffusion, and allow enough stabilization time before span adjustment.
Final checks before design freeze
Validate the complete ozone instrument at the concentration, gas mixture, humidity and sample path expected in service. O₃ range, selectivity and reactive-gas transport all affect the finished measurement.
- Separate ambient / worker-safety range from generator or process concentration.
- Check NO₂, Cl₂ and other oxidant cross-sensitivities.
- Use filtered / differential architectures where O₃ and NO₂ must be separated.
- Validate tubing, filters and enclosure materials for ozone compatibility.
- Keep condensation and contaminated surfaces out of the gas path.
- Account for MOS heater power and stabilization where semiconductor sensing is used.
- Confirm whether the requirement is gaseous O₃ or dissolved ozone in water.
Need an ozone sensor for an OEM project?
Send the target range, ambient / safety / disinfection / process application, expected interferents, sampling method and output interface. Manufacturers can also submit O₃ sensor models with an official product page and current datasheet.
Specifications and product availability can change. Confirm the latest manufacturer datasheet before engineering, compliance or purchasing decisions.