# Monitoring System Enhancing the Potential of Urban Bekeeping
## 2 Methods
### Monitoring System Overview
#### 2.2.1 Multi-Sensor Device
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sensor** & **Measured** & **Detection** & **Measurement Range** & **Accuracy** & **Resolution** & **Repeatability** & **Long Term Drift** \\ \hline \multirow{3}{*}{SHT25} & Temperature & \multirow{3}{*}{Relative} & \multirow{3}{*}{band gap} & \(-\)40–125 °C & \(\text{typ}\pm 0.2\) °C & 0.01 °C & \(\pm 0.1\) °C & \(<\)0.02 °C/y \\  & & & & \(\text{typ}\pm 1.8\) °C & 0.04\% RH & \(\pm 0.1\)°RH & \(<\)0.25\% RH/yr \\  & & & & & \(\pm 10\) mg/m\({}^{*}\) & & & \(\pm 1.25\)\% \(\mu\)g/m\({}^{3}\) \\ \multirow{3}{*}{SPS30} & Particulate & \multirow{3}{*}{laser scattering} & \multirow{3}{*}{0–1000 \(\text{\mu g/m}^{3}\)} & \(\pm\) 10\% m.v.* & \multirow{3}{*}{float values} & \multirow{3}{*}{-} & /year \\  & & & & & *device-to-device & & & \(\pm 1.25\)\% m.v. \\  & & & & & aerosol & & & /year \\ \multirow{3}{*}{SCD30} & Carbon dioxide & \multirow{3}{*}{NDIR sensor} & \multirow{3}{*}{400–10,000 ppm (with declared accuracy)} & \multirow{3}{*}{float values} & \(\pm\)30 ppm & \multirow{3}{*}{with ASC field} \\  & & & & & +3 \% m.v.) & & & & calibration \\ \multirow{3}{*}{PID AH2} & TVOCs with & \multirow{3}{*}{photoionisation \(\text{\textless{}}\)10.6 eV} & \multirow{3}{*}{photoionisation \(\text{\textless{}}\)8 detector} & 1 ppb–50 ppm & & - & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \multirow{3}{*}{SGP41} & \multirow{3}{*}{TVOC and NOx} & \multirow{3}{*}{dual channel \(\text{\textless{}}\)8 sensor} & \multirow{3}{*}{\(\text{\textless{}}\)10 ppm specified \(\text{\textless{}}\)15\% m.v. * & \multirow{3}{*}{nonlinear} & \(\text{\textless{}}\)15\% & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \multirow{3}{*}{SGP41} & \multirow{3}{*}{TVOC and NOx} & \multirow{3}{*}{MOX gas sensor} & \multirow{3}{*}{\(\text{\textless{}}\)10 ppm NOx} & \multirow{3}{*}{\(\text{\textless{}}\)15\% m.v. * & \multirow{3}{*}{nonlinear} & \(\text{\textless{}}\)15\% & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline \hline \end{tabular}  
* device-to-device variation with KCl aerosol.  
\end{table} 
Table 1: The measurement characteristics of sensors included in the multi-sensor device. different. We are interested in continuously monitoring the total amount of volatile organic compounds in beehive air. There are premises to expect that their concentration inside the beehive is related to multiple aspects of the honey bee colony life and performance, e.g., its health (diseases), activity level, currently exploited sources of nectar, etc. However, in urban conditions, there are numerous other sources of volatile compounds, e.g., vehicles, industry, urban infrastructure, city operation, and activities of citizens. The relative contribution of these sources versus honey bee colonies' contribution to the beehive atmosphere has not been recognized so far. In our system, we test the performance of two kinds of sensors for VOCs measurement. They are based on different measurement principles namely, SGP41 is a semiconductor gas sensor and the PID AH2 is a photoionization sensor. The sensors differ regarding their sensitivity to the individual volatile compounds and the measurement ranges, see Table 1. We also expect a difference in terms of lifetime. Regarding price, the SGP41 sensor is very cheap, while the PID AH2 sensor is considerably more expensive. The monitoring data on NOx comes as an added value associated with the use of the SGP41 sensor, which is primarily applied for TVOC measurement. Still, we are going to carefully look at this parameter. Its content in beehive air as compared with ambient air is of particular interest in the summertime when the probability of urban photochemical smog increases. Similar to VOCs, the particulate matter concentration measurement in beehives is very uncommon. As a consequence, the value of this parameter for the characterization of bee colonies remains unexploited. We intend to collect the data which may be the basis for the respective analysis.