High-Performance VOC Detection for Air Quality, Safety & Industrial Hygiene


Alphasense VOC sensors deliver reliable detection of volatile organic compounds across air quality, industrial hygiene, indoor environmental monitoring and safety applications. With both electrochemical VOC sensors (VOC-A4, VOC-B4) and a full portfolio of photoionisation detectors (PIDs) (PID-A Series and PIDX-A Series), OEMs gain flexible options for low-level ppb monitoring through high-range industrial VOC measurements.

All VOC sensors are engineered for stability, fast response and seamless integration, enabling high-performance analyzers and monitors across portable, fixed, wearable and environmental platforms.


Sensor Product Overview


Alphasense supports two complementary VOC detection technologies — electrochemical VOC sensors and advanced PIDs — covering extremely low concentrations through high-range industrial environments.

Electrochemical VOC Sensors - PPB-Level Analysis


  • VOC-A4 — A-Series 4-electrode VOC sensor for portable, handheld and air-quality instruments; 0–100 ppm range with optional bias for selectivity.
  • VOC-B4 — B-Series 4-electrode VOC sensor for fixed installations, high-humidity environments, and long-term outdoor air-quality monitoring; 0–100 ppm range with optional bias for selectivity.
These sensors offer high sensitivity with extremely low noise when used with AFE / ISB boards, making them ideal for ppb-level VOC detection.

Integrated Smart Technology (IST) VOC Sensor Versions


Both VOC-A4 and VOC-B4 sensors are also available with IST—Integrated Smart Technology.
These VOC-A4+ and VOC-B4+ sensors provide:

  • On-sensor calibration storage for consistent long-term network operation
  • Integrated temperature sensor for robust environmental compensation
  • Excellent for fixed AQ nodes, industrial sites, and high-humidity environments
  • Simplifies maintenance across distributed field installations

PID Sensors - Wide-range photoionisation detection

Standard PID A-Series:


Advanced PIDX A-Series:


  • PIDX-A-004 — 0–4 ppm for indoor air quality and cleanroom monitoring
  • PIDX-A-020 — 0–20 ppm for IAQ and environmental use
  • PIDX-A-040 — 0–40 ppm for portable and confined-space instruments
  • PIDX-A-200 — 0–200 ppm for environmental and industrial VOC monitoring
  • PIDX-A-04K — 0–4000 ppm for oil & gas, petrochemical and safety applications
  • PIDX-A-10K — 0–10,000 ppm for high-concentration industrial and process environments

Choosing the Right VOC Sensor by Application


Air Quality & Low-Level Environmental Monitoring (PPB–PPM)


Choose: VOC-A4, VOC-B4, PIDX-A-004, PIDX-A-020, PIDX-A-040 

  • Ideal for long-term environmental monitoring, IAQ devices, research instruments, and low-range portable VOC monitors.
  • A-Series fits portable analyzers; B-Series suits fixed networks and humid outdoor sites.

Oil & Gas, Petrochemical, Industrial Safety (High-Range VOCs)


Choose: PIDX-A-04K, PIDX-A-10K

  • Wide-range sensors able to handle very high VOC concentrations while maintaining stability.
  • Used in leak detection, process control, and industrial hygiene.

Portable Industrial Hygiene & Confined Space Entry


Choose: PID-A15, PID-AG5, PID-AH5, PID-AR5, PID-AY5, PIDX-A-040, PIDX-A-200 

  • Robust PIDs with fast response for worker safety instruments and personal monitors.

Fixed Installations & High-Humidity Environments


Choose: VOC-B4, PID-A15 / PID-AR5, PIDX-A-200 

  • Larger electrolyte volume in VOC-B4 for stability; PIDs maintain performance in variable conditions.

Key Benefits Across the VOC Sensor Portfolio


  • Comprehensive coverage: ppb electrochemical VOC detection through 10,000 ppm PID solutions
  • Multiple form factors: A-Series, B-Series, and PID housings for portable, fixed, wearable and OEM-specific designs
  • High sensitivity: 4-electrode electrochemical VOC sensors designed for extremely low baseline drift
  • Robust PID technology: Stable 10.6 eV lamps, fast T90 response and wide dynamic range for industrial environments
  • Low noise when paired with AFE / ISB boards: Enables precise ppb-level VOC measurement in AQ applications
  • Designed for demanding conditions: Options optimized for humidity extremes, outdoor climates and difficult industrial settings

Why OEMs Choose Alphasense


OEMs rely on Alphasense VOC solutions because they offer:

  • Consistent manufacturing for long-term instrument stability
  • Broad technology choice: electrochemical + PID options to fit all applications
  • Integration-friendly designs: standard A-series footprints, PIDs with high sensor-to-sensor repeatability
  • Strong technical support and established compatibility with AFE, ISB, and PID accessories
  • Long product lifecycles supporting stable analyzer designs

How VOC Sensors Work


Electrochemical VOC Sensors


Alphasense VOC-A4 and VOC-B4 sensors use a 4-electrode electrochemical cell where VOCs undergo controlled oxidation or reduction at the working electrode.

  • The reaction generates a current proportional to VOC concentration.
  • Auxiliary electrodes support correction for zero current and temperature zero current shift.
  • External AFE/ I SB electronics measure the resulting current for ppb-level accuracy.

Photoionisation Detectors (PIDs)


Alphasense PID and PIDX sensors use 10.6 eV UV lamps to ionize VOC molecules.

  • Ionized gas molecules produce a measurable current in the ionization chamber.
  • The signal is directly proportional to VOC concentration.
  • PIDs offer fast response, wide dynamic range and excellent repeatability.

Why Measure VOCs


VOCs are significant indicators of air quality, industrial safety and worker exposure. Monitoring VOCs helps:

  • Protect workers from hazardous airborne chemicals
  • Ensure compliance with environmental and occupational regulations
  • Detect leaks in industrial and petrochemical processes
  • Maintain healthy indoor environments
  • Improve understanding of chemical emissions, pollution events and cleanroom contamination

Select VOC Sensor

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