Research Overview

Research Background: What Problem Did This Study Address?

Accurate particulate matter, or PM, filter weighing is essential for air quality monitoring. PM10, PM2.5, and PM1 concentrations are often determined by collecting particles on filters and then calculating the mass difference before and after sampling. Because the mass changes can be very small, even slight environmental fluctuations can affect measurement accuracy.

Temperature and relative humidity are particularly important. Filters and collected particulate matter can absorb or release water depending on ambient humidity. Low humidity may also increase electrostatic effects, especially for PTFE filters. For this reason, gravimetric standards require filters to be equilibrated under controlled conditions before weighing.

This study examined how environmental conditions, operational procedures, and filter materials affect robotic gravimetric weighing of PM filters. The researchers compared glass fiber, quartz fiber, and PTFE O-ring filters under different temperature and relative humidity conditions. They also compared robotic weighing with manual weighing and tested whether rotor movement inside the robotic weighing system introduced measurement drift.

UbiBot WS1 Pro was used to record the temperature and relative humidity conditions in the filter conditioning room. These environmental data helped document whether filters were prepared under stable, controlled conditions before robotic and manual weighing comparisons were performed.

The Specific Role of UbiBot in the Study

In this study, UbiBot WS1 Pro was used as an environmental monitoring device for the filter conditioning room. The paper does not present UbiBot as the instrument that weighed filters or proved the reliability of the robotic weighing system. Instead, UbiBot recorded real temperature and relative humidity conditions during the filter conditioning process, providing environmental context for the gravimetric analysis.

The research team used 47 mm particulate matter filters made of glass fiber, quartz fiber, and PTFE O-ring material. Before and after PM exposure, the filters were conditioned in the weighing room for 48 hours. The conditioning conditions were set at 45% relative humidity and 21 °C air temperature.

During this conditioning stage, a UbiBot WS1 Pro measuring device equipped with a TH30S-B external temperature and humidity probe recorded the weighing-room environment every five minutes. The TH30S-B probe had a temperature measurement range from +40 °C to +125 °C with an accuracy of ±0.3 °C, and a humidity measurement range from 0 to 100% RH with an accuracy of ±2%.

These UbiBot records were used to document the environmental stability of the filter conditioning process. This mattered because the study’s later comparisons depended on the filters starting from a controlled and reproducible state. If filters had not been conditioned under known temperature and humidity conditions, changes in measured mass could have been incorrectly attributed to the robotic weighing system, filter material, or chamber conditions.

UbiBot was not installed inside the robotic weighing chamber. The chamber itself used its built-in environmental sensor, and two additional Radwag THB S and THB P sensors were installed inside the RWS chamber for reference. UbiBot’s role was specifically connected to the weighing-room conditioning environment before and after filter exposure.

Therefore, UbiBot’s contribution can be summarized as environmental condition documentation for PM filter preparation. It supplied the time-series temperature and humidity record needed to support standardized filter conditioning, reduce uncertainty, and make the subsequent robotic-versus-manual weighing and filter-material comparisons more reliable.

Research Methods and Data Collection Approach

The researchers tested three types of Whatman 47 mm PM filters: glass fiber GF/A, quartz fiber QMA, and PTFE O-ring filters. A total of 50 filters were exposed for particulate matter collection at an urban background site in Zabrze, Poland, during the winter period from November 24, 2022 to February 6, 2023.

The filters were used to collect PM1 and PM2.5 fractions. Ten glass filters and ten quartz filters were used for PM1. Another ten glass filters, ten quartz filters, and ten PTFE O-ring filters were used for PM2.5. Ten blank filters of each material type were also used as references.

Before and after exposure, the filters were conditioned for 48 hours in the weighing room. The target conditioning environment was 45% relative humidity and 21 °C. The room’s relative humidity was maintained by an automatic humidifier/dehumidifier. UbiBot WS1 Pro with TH30S-B probe recorded room temperature and relative humidity every five minutes during this stage.

After conditioning, filters were weighed using the UMA 2.5Y.FC Robotic Weighing System. This RWS included a built-in environmental chamber, a 24-position rotor for filter cases, and an automatic balance with 1 µg readability. During robotic measurements, the chamber maintained operator-defined temperature and humidity conditions. The researchers tested multiple chamber settings: 35%, 45%, and 55% RH combined with 18 °C, 21 °C, and 24 °C, resulting in nine environmental condition combinations.

The study also compared robotic weighing with manual weighing using the MYA 5.4Y.F balance. An antistatic ionizer was applied before filters were placed into the RWS rotor, especially because PTFE filters can accumulate electrostatic charges.

To test operational influence, two reference PTFE O-ring filters were placed on opposite sides of the RWS rotor. The system measured them repeatedly over three hours under stable 45% RH and 21 °C conditions. The rotor performed half-spins, and 90 measurements were collected for each reference filter. Statistical analyses included standard deviation analysis, Shapiro–Wilk tests, factorial ANOVA, one-way ANOVA, and paired t-tests.

Key Research Findings

The study found that temperature and relative humidity changes inside the robotic weighing chamber did not significantly affect PM filter mass measurements under the tested conditions. Factorial ANOVA across glass, quartz, and PTFE O-ring filters showed a very high p-value of 0.99998, indicating no statistically significant effect of temperature or relative humidity on measured filter mass.

The same conclusion held for blank filters. Factorial ANOVA showed no significant influence of temperature or relative humidity on blank filter masses. This suggests that pre-conditioning, fast RWS measurement time, and controlled chamber operation effectively minimized environmental effects on weighing results.

Filter material still mattered. Glass filters generally showed the lowest variability and strong stability. Quartz filters also performed reliably, although PM1 quartz filters sometimes showed higher variability. PTFE O-ring filters showed higher absolute variability after exposure, but they were less sensitive to changing humidity and temperature, likely due to hydrophobic material properties.

The study also found that antistatic treatment is important for PTFE O-ring filters. Without antistatic treatment, PTFE filters showed abnormal fluctuations, indicating that electrostatic charge can interfere with stabilization and weighing precision.

The operational test showed that rotor movement itself had only a minor effect over short intervals. However, over three hours, paired t-tests and ANOVA detected small but statistically significant changes in measured mass. The mean changes were extremely small, but the result suggested subtle drift over time, possibly related to filter stabilization, equipment operation, or small environmental changes.

The comparison between robotic and manual weighing showed strong consistency. Differences for blank glass filters were generally within 2.5–10 µg, quartz filters typically differed by 14–27 µg, and PTFE filters showed larger variation in some cases. One-way ANOVA confirmed no statistically significant difference between robotic and manual weighing methods.

What This Means for PM Filter Weighing and Air Quality Monitoring

This study shows that automated robotic weighing systems can support high-throughput PM filter analysis without compromising measurement reliability, provided that filter conditioning, chamber control, antistatic treatment, and system monitoring are properly managed.

For air quality monitoring networks, this is important because national and regional programs may process thousands of filters every year. Manual weighing is labor-intensive and can introduce operator handling variability. Robotic systems can reduce handling, automate sequential measurements, and improve standardization.

The findings also highlight why environmental records are essential. Gravimetric PM analysis depends on very small mass differences. Documenting temperature and relative humidity during filter conditioning helps ensure that mass changes reflect particulate matter loading rather than moisture uptake, drying, or unstable laboratory conditions.

For regulatory monitoring, the study is especially relevant because stricter air quality standards require robust and reproducible measurements. A combination of stable conditioning, environmental logging, antistatic treatment, and validated robotic weighing can improve data quality for PM10 and PM2.5 compliance assessment.

Application Value of UbiBot Devices

UbiBot WS1 Pro demonstrated practical value as a condition-monitoring tool in the gravimetric PM filter workflow.

First, it provided time-stamped temperature and relative humidity data during the 48-hour filter conditioning period. This helped document that filters were prepared under controlled environmental conditions before weighing.

Second, it supported compliance-oriented quality assurance. PM filter weighing standards require controlled temperature and humidity during equilibration. UbiBot records helped preserve evidence of the conditioning environment.

Third, UbiBot data helped reduce uncertainty in later weighing comparisons. Because the conditioning environment was monitored, the researchers could more confidently interpret differences between filter materials, robotic weighing, and manual weighing.

Fourth, the external TH30S-B probe allowed temperature and humidity monitoring with specified measurement accuracy, suitable for documenting laboratory environmental conditions.

Fifth, UbiBot’s role complemented the RWS and manual balances. UbiBot did not measure filter mass; instead, it supplied the environmental record that supported reliable gravimetric measurement.

Overall, UbiBot’s value in this paper lies in environmental monitoring for measurement quality assurance. It helped connect filter conditioning conditions with later gravimetric weighing reliability.

Extended Application Scenarios

The monitoring approach used in this study can be extended to several related scenarios:

1. PM filter conditioning rooms
   Used to record temperature and humidity during filter equilibration before and after sampling.
2. Air quality monitoring laboratories
   Used as part of quality assurance workflows for gravimetric PM analysis.
3. Robotic weighing system validation
   Used to document ambient conditions when comparing automated and manual weighing methods.
4. Filter material comparison studies
   Used to monitor environmental conditions when testing glass, quartz, PTFE, or other filter media.
5. Environmental chamber verification
   Used as an independent logging layer around weighing, conditioning, or equilibration equipment.
6. Regulatory compliance documentation
   Used to provide time-series temperature and humidity records for audit and data traceability.
7. Aerosol research laboratories
   Used to support experiments where PM mass is sensitive to moisture uptake or loss.
8. Long-term monitoring network QA/QC
   Used to standardize laboratory environmental records across multiple PM monitoring sites.

FAQ

1. Which UbiBot product was used in the study?

The study used a UbiBot WS1 Pro measuring device equipped with an external TH30S-B temperature and humidity probe.

2. What data did UbiBot collect?

UbiBot recorded temperature and relative humidity in the filter conditioning / weighing room.

3. Where was UbiBot deployed?

It was used in the weighing room during PM filter conditioning before and after sampling.

4. What was the sampling frequency?

Temperature and relative humidity were recorded every five minutes.

5. How long were filters conditioned?

Filters were conditioned for 48 hours before and after exposure under 45% RH and 21 °C conditions.

6. Did UbiBot weigh the PM filters?

No. Filter mass was measured by the UMA 2.5Y.FC Robotic Weighing System and by the MYA 5.4Y.F manual balance. UbiBot monitored the conditioning-room environment.

7. How were UbiBot data used?

The data documented the temperature and humidity conditions during filter conditioning, supporting quality control and interpretation of later weighing results.

8. What filters were studied?

The study tested glass fiber, quartz fiber, and PTFE O-ring filters.

9. What was the main result?

Temperature and relative humidity changes inside the robotic weighing chamber did not significantly affect filter mass measurements under the tested conditions. Robotic and manual weighing results were statistically consistent.

10. Why is this research important?

Accurate gravimetric filter weighing underpins PM2.5 and PM10 monitoring. Environmental logging during conditioning helps improve traceability, repeatability, and confidence in air quality data.