Details

Nanomaterials owe their unique properties to their small size. At the same time, this very feature is problematic due to the safety and health hazards. Employees manufacturing these products are exposed to harmful effects, mostly as a result of inhalation. The currently available devices for nanoaerosol sensing are relatively complex and expensive. There is therefore a need to simplify and reduce the costs of devices for nanoparticles detection. Ionization smoke detectors are used to identify fires at an early stage, when only a small amount of thin smoke is produced. This has spawned the idea to study their usability for nanoparticles detection in the work environment.

The detector has been modified by exposing signals from both reference and active chambers. Radioactive isotope Americium-241 ionizes the air creating a current flow between two electrodes. When ions recombine with aerosol particles in the active chamber, a voltage difference is created proportional to the particles’ concentration. When the voltage difference reaches a level above the set threshold, a fire alarm is triggered. Voltage signals from both chambers were measured using microcontroller with an analog digital converter and an operational amplifier used as a voltage follower. The output signal was calculated as the difference between the two voltage signals.

The device was placed in a sealed container with inlet and outlet hose connectors. Nanoaerosol was produced using a Palas GFG 1000 generator with graphite electrodes. TSI NanoScan SMPS 3910 was used as a reference device for nanoparticles concentration measurements.

The value of the output signal from the modified detector increases with the increasing number of aerosol particles. The relationship may be estimated from linear trend line in the aerosol concentration range up to 8.3×10^5 particles/cm^3. Low-cost detectors with such response characteristic could be used to assess long-term exposure in real time as well as to detect unforeseen events.