# Identification of Emission Source Using a Micro Sampler Carried by a Drone
###### Abstract  
A micro needle trap sampler (NTS) was carried by a mini quadrotor drone (Mavic Pro, DJI) to collect volatile organic compounds (VOCs) from industries. The NTS was fabricated using a 7 cm long, 22-gauge stainless steel needle by packing powdered divinylbenzene (DVB) adsorbents (60-80 mesh diameters). The telescoping sampling shaft was installed on the drone to extend the NTS beyond the downward air turbulence that was caused by the rotation of its propellers. The total mass of the sampling device, including an NTS, a telescoping shaft, a mini-air pump, and an ABS (acrylonitrile butadiene styrene) rack, was not more than 200 g. The emitted VOCs, those from a steel processing plant, including aromatic hydrocarbons (toluene of 15 ppb, ethylbenzene of 9 ppb and p-xylene 12 ppb), and those from a semiconductor processing factory, including trace amounts of methanol (1.96-2.00 ppm), acetone (0.05-0.10 ppm), and toluene (1.04-2.00 ppm), were extracted by the NTS on the drone and identified using a gas chromatography-mass spectroscopy (GC-MS) system in the laboratory. According to the results of VOC detection during the sampling flight of a drone, the stationary pollution sources were successfully identified. drone; air sampling; needle trap sampler; monitoring; volatile organic compounds +
Footnote †: journal: Physics Letters B  
1
Footnote 1: email: {[[https://www.mdpi.com/journal/drones/2022/1/0](https://www.mdpi.com/journal/drones/2022/1/0)]([https://www.mdpi.com/journal/drones/2022/1/0](https://www.mdpi.com/journal/drones/2022/1/0))  
to monitor VOC emissions to ensure that various pollution sources have been improved to achieve the reduction of VOCs. KEPB had installed 1250 micro sensor boxes in the industrial zones that surround Kaohsiung City by 2019 [13]. Micro sensors, which monitor temperature, humidity, PM\({}_{10}\), PM\({}_{2.5}\), and total volatile organic compounds (TVOCs), have been installed in areas with a high density of factories at a height of 3 m, and in communities adjacent to industrial areas at a height of 1.5-2 m. The obtained concentration data were delivered from a micro sensor box every 3 min to the management center via a wireless network. The main function of the micro sensors is to monitor emission from sources of air pollution in an air pollution hot zone, assisting the KEPB enforce limits on industrial pollution emissions [14]. To increase the three-dimensional mobility of sensing devices for air pollution, the Environmental Protection Bureau of Taoyuan City, northern Taiwan, uses an unmanned drone to carry sensors of TVOCs, and the technology has been developed by Chung Yuan Christian University to monitor pollutants in the atmosphere [15]. However, identifying an industrial emission source by measuring only concentrations of TVOCs, whose individual organic components cannot be exactly examined, is difficult. Owing to the inadequacy of currently used air monitors, several air sampling devices have been developed for transport on a drone to take air samples for the subsequent qualitative and quantitative analysis of individual organic components in the laboratory. The NTS, carried on a drone with a telescopic sampling device, that extends the NTS beyond the strong downdraft stream that is generated by the propellers of a drone, has been proved to be feasible means of taking representative air samples for VOC analysis [16; 17]. A mini drone (Mavic Pro, DJI), carrying an NTS (Figure 1), is a small, unmanned air vehicle (UAV) for sampling, and it is especially suitable for collecting VOCs that are emitted around industrial areas. Two real cases of the use of a drone with an NTS to identify industrial VOC emission sources are presented herein. Figure 1: An needle trap sampler carried by a drone using the telescopic device. Site B is located close to the boundary of an electronic processing park in Kaohsiung City.