VOC Gas Sensor Module

Volatile organic compounds encompass thousands of different chemical species — from the solvents used in paints and coatings to the hydrocarbons emitted by vehicles, industrial processes, and building materials. Monitoring individual VOC species requires expensive gas chromatography equipment, but for most environmental monitoring applications, a total VOC (TVOC) measurement provides the screening data needed to identify pollution events, track emission trends, and assess air quality. The Sensorbee VOC Sensor uses metal oxide semiconductor (MOS) technology to detect a broad spectrum of volatile organic compounds across a 0–60,000 ppb range with 1 ppb resolution and a fast 30-second response time.

How It Works

The VOC sensor uses metal oxide semiconductor (MOS) detection — a fundamentally different technology from the electrochemical sensors used for specific gas species like NO2, SO2, and H2S. A heated metal oxide film changes its electrical resistance when volatile organic compounds adsorb onto its surface. The magnitude of this resistance change is proportional to the total VOC concentration in the sampled air.

The MOS approach provides broad-spectrum detection rather than gas-specific measurement. The sensor responds to a wide range of organic compounds including:

• Alcohols — ethanol, methanol, isopropanol from industrial solvents and cleaning products
• Aldehydes — formaldehyde, acetaldehyde from building materials, furnishings, and combustion
• Aromatic compounds — benzene, toluene, xylene from vehicle emissions, fuels, and industrial processes
• Organic acids — acetic acid and other volatile acids from fermentation and decomposition
• General organic vapours — a wide range of additional VOC species that contribute to air quality degradation

This broad sensitivity makes the MOS sensor ideal for total VOC screening, where the goal is to detect the presence and magnitude of organic contamination rather than identify specific chemical species.

Why VOC Monitoring Matters

Volatile organic compounds matter for both health and environmental reasons:

• Health effects — many VOCs are irritants at moderate concentrations and some (benzene, formaldehyde) are classified carcinogens. Chronic exposure to elevated VOC levels in indoor and outdoor environments is associated with respiratory symptoms, headaches, and long-term health risks
• Ozone precursors — VOCs react with nitrogen oxides in sunlight to form ground-level ozone. Monitoring VOC concentrations helps assess photochemical smog potential and supports ozone management strategies
• Indoor air quality — new buildings, renovations, furnishings, and cleaning products release VOCs that affect occupant comfort and health. TVOC monitoring provides a general indicator of indoor air contamination
• Odour assessment — many VOCs have low odour thresholds. TVOC measurements complement specific odour gas monitoring (H2S, NH3) at waste and industrial facilities
• Regulatory compliance — industrial processes using solvents, coatings, and organic chemicals may face VOC emission limits under environmental permits

Measurement Performance

The VOC sensor covers a 0–60,000 ppb detection range with 1 ppb resolution — providing both the sensitivity to detect low-level indoor air quality changes and the range to monitor industrial emission events where VOC concentrations can reach tens of thousands of ppb.

The sub-30-second response time (t90) makes this the fastest-responding sensor in the Sensorbee gas sensor range. Fast response is valuable for:

• Event detection — quickly identifying VOC release events from industrial processes, spills, or equipment malfunctions
• Indoor ventilation assessment — tracking rapid VOC concentration changes when windows are opened, ventilation rates change, or new materials are introduced
• Mobile monitoring — capturing spatial VOC profiles when the sensor platform moves through different environments

Power consumption is under 100 mW. While higher than the 50 mW ammonia sensor (due to the heated sensing element), it remains compatible with the overall power budget of solar-powered Sensorbee monitoring platforms.

MOS vs Electrochemical: Different Tools for Different Jobs

The VOC sensor's metal oxide semiconductor technology complements rather than competes with the electrochemical sensors in the Sensorbee range:

• Electrochemical sensors (NO2, SO2, O3, CO, H2S, NO) measure specific gas species with high selectivity and certified accuracy. Use these when you need to know the exact concentration of a particular pollutant
• MOS VOC sensor provides total volatile organic compound measurement across hundreds of species simultaneously. Use this when you need to screen for the presence of organic contamination, track emission trends, or assess general air quality

For comprehensive monitoring, deploy both — specific gas sensors for regulated pollutants and the VOC sensor for broad organic compound screening.

Extended Operational Life

The MOS sensing element delivers over two years of operational life — double the standard one-year life of the electrochemical gas sensors. Metal oxide semiconductor sensors do not consume chemical reagents during measurement, so the sensing element does not deplete with use. This extended life reduces replacement frequency and maintenance costs for long-term monitoring programmes.

Integration With Sensorbee Platforms

The VOC sensor connects to the Air Pro 2 and Air Lite via the M8 connector interface — the same compact, moisture-resistant connector used by the ammonia sensor. The base station handles data acquisition, processing, and transmission to the Sensorbee Cloud.

For indoor air quality applications, combine the VOC sensor with:

• CO2 sensor (SB4212) — ventilation adequacy indicator alongside VOC contamination measurement
• EnviroSense module (SB4502) — temperature, humidity, and pressure for complete indoor environmental profiling

For industrial and outdoor applications, the VOC sensor complements specific gas sensors to provide a layered monitoring approach — specific pollutant measurement plus broad organic compound screening.

Applications

• Indoor air quality monitoring — TVOC measurement in offices, schools, hospitals, and residential buildings to assess organic contamination from furnishings, cleaning products, and building materials
• Construction site monitoring — track VOC emissions from painting, coating, adhesive application, and solvent use during construction and renovation activities
• Industrial emission monitoring — perimeter VOC screening at manufacturing facilities, chemical plants, and process operations where organic compounds are used or produced
• Urban pollution assessment — TVOC data complements specific pollutant measurements for comprehensive air quality characterisation in urban environments
• Waste facility monitoring — detect organic compound emissions at landfills, composting facilities, and waste transfer stations alongside H2S and NH3 monitoring
• Environmental impact assessments — VOC baseline and operational monitoring for planning applications involving industrial, commercial, or construction activities

Frequently Asked Questions

Can this sensor identify specific VOC species?

No — the MOS sensor provides a total VOC (TVOC) measurement that represents the combined response to all organic compounds present. Identifying individual species (e.g., benzene, toluene) requires gas chromatography instrumentation. The VOC sensor is a screening tool that indicates the presence and magnitude of organic contamination.

What units does the sensor report?

The sensor reports in ppb (parts per billion), referenced to a standard calibration gas. Because MOS sensors respond differently to different organic compounds, the ppb reading represents an equivalent concentration rather than a true species-specific measurement. The reading is most accurate for compounds similar to the calibration reference.

How does humidity affect VOC readings?

The MOS sensing element can be influenced by humidity changes. The sensor operates across 0–95% RH, and the Sensorbee platform applies compensation algorithms to minimise humidity-related measurement drift. For highest accuracy, compare VOC data collected under similar humidity conditions.

Can I use this alongside the H2S and NH3 sensors?

Yes — deploying the VOC, H2S, and NH3 sensors together on the same Air Pro 2 base station creates a comprehensive odour and air quality monitoring system. The H2S sensor detects sulfur-based odour compounds, the NH3 sensor measures ammonia, and the VOC sensor provides broad coverage of organic odour and contamination compounds.

Why does this use MOS technology instead of electrochemical?

Electrochemical sensors are designed for high selectivity to a single gas species. VOC monitoring requires broad-spectrum detection across hundreds of different organic compounds simultaneously. MOS technology's inherent multi-compound sensitivity is an advantage here — what would be cross-sensitivity in a specific gas sensor becomes the desired broad detection capability for VOC screening.