| 1 | UV Absorption Photometric | Measures ozone absorption near 254 nm using the Beer–Lambert law. | Approximately 0–1,000 ppm; environmental instruments may cover low-ppb levels. | Typically ±1–2% of reading or better after calibration. | About 1–30 seconds. | Industrial ozone generators, water treatment, process control, ambient air monitoring, and medical ozone equipment. | Excellent selectivity, non-contact measurement, good long-term stability, and no consumable reagent. | Higher cost than basic electrochemical devices; requires clean optical paths and controlled flow. |
| 2 | Electrochemical Amperometric | Ozone is reduced or oxidized at an electrode, producing a current proportional to concentration. | Approximately 0–20 ppm for gas; specialized cells can support higher ranges. | Typically ±2–5% of full scale. | About 30–90 seconds. | Personal safety monitors, room monitoring, HVAC systems, and compact medical or laboratory instruments. | Low power consumption, compact size, relatively low purchase cost, and simple electronics. | Limited sensor life, humidity and temperature effects, cross-sensitivity, and periodic replacement requirements. |
| 3 | Metal-Oxide Semiconductor | Ozone changes the electrical resistance of a heated metal-oxide sensing layer. | Approximately 0.01–100 ppm, depending on design and operating temperature. | Commonly ±10–20% of reading after calibration. | About 10–120 seconds. | Low-cost indoor-air monitors, smart appliances, ventilation systems, and general warning devices. | Low unit cost, robust construction, simple integration, and suitability for compact products. | Strong cross-sensitivity to other oxidizing gases, baseline drift, heater power consumption, and lower accuracy. |
| 4 | Colorimetric Indigo or DPD | Ozone reacts with a chemical reagent, and the resulting color change is measured optically. | Typically 0.01–1.00 mg/L in water, equivalent to 0.01–1.00 ppm as O3. | Often ±0.01–0.05 mg/L, depending on method and instrument. | About 1–10 minutes per test. | Drinking-water plants, swimming pools, laboratories, food sanitation, and process-water testing. | Simple chemistry, good sensitivity in water, and useful for field verification or reference checks. | Requires reagents and sample handling; not a continuous gas-phase sensor; color interference may affect results. |
| 5 | Iodometric Wet-Chemistry Analyzer | Ozone liberates iodine from iodide; the iodine is measured by titration or optical detection. | Approximately 0.01–100 mg/L in water, depending on the sampling and titration method. | Typically ±1–5% of reading in a controlled laboratory procedure. | About 2–20 minutes. | Laboratory reference testing, ozone-generator validation, and high-level water-process verification. | Established analytical chemistry, useful over a broad dissolved-ozone range, and suitable for validation work. | Uses reagents, produces chemical waste, requires trained operators, and is not ideal for fast continuous control. |
| 6 | Chemiluminescence | Ozone reacts with a reagent such as ethylene, producing light proportional to ozone concentration. | Approximately 0.1 ppb–10 ppm. | Typically ±1–5% of reading in laboratory-grade systems. | Sub-second to approximately 10 seconds. | Research laboratories, atmospheric studies, calibration systems, and high-sensitivity environmental monitoring. | Very high sensitivity and fast response at low ambient ozone concentrations. | Requires a reagent supply, careful optical maintenance, controlled sampling, and higher operating cost. |
| 7 | UV-LED Absorption | A UV LED and photodetector estimate ozone from attenuation at or near the ultraviolet absorption band. | Approximately 0.01–100 ppm. | Typically ±3–10% of reading, depending on optical design and calibration. | About 1–20 seconds. | Portable instruments, embedded process monitors, air-treatment equipment, and compact medical devices. | Compact, low power compared with many UV-lamp systems, fast, and free of wet reagents. | LED aging, temperature dependence, optical contamination, and lower performance than premium reference photometers. |
| 8 | Photoacoustic Spectroscopy | Modulated optical absorption creates pressure waves that are detected by a microphone or acoustic sensor. | Approximately 1 ppb–100 ppm, depending on optical path and configuration. | Typically ±2–5% of reading in calibrated instruments. | About 1–10 seconds. | Advanced environmental monitoring, industrial process analysis, and multi-gas research systems. | High sensitivity, compact optical path, and potential for simultaneous multi-gas measurement. | Sensitive to acoustic noise, pressure changes, humidity effects, and complex calibration requirements. |
| 9 | Cavity-Enhanced Absorption | Multiple reflections inside an optical cavity create a long effective path for highly sensitive absorption measurement. | Approximately 0.1 ppb–100 ppm. | Typically ±1–3% of reading after calibration. | About 1–30 seconds. | Atmospheric research, emissions studies, laboratory analysis, and high-end process monitoring. | Very high sensitivity, strong detection capability at low concentrations, and reagent-free operation. | Higher cost, optical alignment requirements, sensitivity to contamination, and greater technical complexity. |
| 10 | Differential Optical Absorption Spectroscopy | Analyzes structured ultraviolet or visible absorption features over an extended optical path. | Typically 1–1,000 ppb for ambient path-integrated measurements. | Commonly ±5–10% of reading, depending on path length and atmospheric conditions. | Several seconds to a few minutes. | Urban air-quality networks, industrial fence-line monitoring, stack or plume studies, and atmospheric mapping. | Remote or open-path operation, long-range coverage, and simultaneous measurement of several gases. | Requires careful alignment and atmospheric correction; results depend on path geometry, weather, and visibility. |