There are three common methods used to detect vapes: Total Volatile Organic Compound (TVOC) and Particulate Matter (PM) sensors or both. In this post, we explain how each of those sensors operates, how they are created, and what can work for vape detection.
Total Volatile Organic Compound (TVOC) Sensor
What is TVOC?
TVOC is a grouping of a wide range of organic chemical compounds to simplify reporting when these are present in ambient air or emissions. Many substances, such as natural gas, could be classified as volatile organic compounds (VOCs). VOCs are reserved for the characterization of such substances in polluted air.
How It Works.
TVOCs are typically constructed using Metal Oxide Semiconductors (MOS). These MOS
sensors function by heating a thin film. This film is heated to 200-400 degrees Celsius. This requires that any TVOC sensor be around 30 – 90 minutes before getting any valuable information. Different Volatile Organic Compounds (VOCs) react to MOS sensors differently, and thus, some form of calibration is required to adjust the sensor’s readings to particulate matter per billion (ppb).
Impact on Vape.
Given that vapes come in all mixtures and have low non-industrial-grade needs, calibration on most over-shelf sensors tends to be less stringent than industrially certified sensors, which cost thousands of dollars just for the sensor. A poorly calibrated sensor can tend to either not trigger any vape or trigger on almost any unnatural air (e.g., the perfume scent of a student walking in, bowel movements, body scent, etc.).
Particulate Matter (PM)
What is PM?
PM stands for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.
How it Works.
Inside a PM is a laser diode that emits light. The particles going through the sensor interact and deflect the light based on their size. The scattered light then interacts with a photodetector that determines the size of the particles based on the intensity of the signals they are measuring via signal processing and classification algorithms.
Impact on Vape.
Since all vape products create a cloud (aerosol mist) after exhaling, there is a consistent pattern that can be detected reliably through the PM sensors, which does not require calibration. However, since PM sensors detect all particles and intensity, a proper global calibration is still needed to ensure the device operates appropriately within an environment.
Conclusions
Both TVOC and PM sensors can detect vaping in different ways. However, TVOC requires more calibration per environment and warm-up to operate correctly. Meanwhile, PM sensors operate once started up right away. Furthermore, some work has noted that TVOC needs to be recalibrated over time (weeks), and industry IoT sensor developers have yet to find a way to enable customers to re-calibrate their sensors with ease.
Learn About How FlySense® Detects Vape
References
Carbon Nanomaterials and their Nanocomposite-Based Chemiresistive Gas Sensors
Applications, Fabrication and Commercialization, Chapter 2 – Semiconductor oxide nanomaterial
https://www.sciencedirect.com/topics/engineering/metal-oxide-semiconductor
What You Need to Know About Particulate Matter Sensors
https://blog.attuneiot.com/particulate-matter-sensors
Particulate Matter (PM) Basic
https://www.epa.gov/pm-pollution/particulate-matter-pm-basics
All vape creates Aerosol mist