Institute of Atmospheric Pollution Research-National Research Council (IIA-CNR), Research Area of Rome 1, Strada Provinciale 35d, 9-00010 Montelibretti, Italy.
National Institute for Astrophysics INAF-IAPS, Via del Fosso del Cavaliere 100, 00133 Rome, Italy.
Sensors (Basel). 2023 Jun 18;23(12):5682. doi: 10.3390/s23125682.
Suspended particulate matter (PMx) is one of the most important environmental pollutants. Miniaturized sensors capable of measuring and analyzing PMx are crucial in environmental research fields. The quartz crystal microbalance (QCM) is one of the most well-known sensors that could be used to monitor PMx. In general, in environmental pollution science, PMx is divided into two main categories correlated to particle diameter (e.g., PM < 2.5 µm and PM < 10 µm). QCM-based systems are capable of measuring this range of particles, but there is an important issue that limits the application. In fact, if particles with different diameters are collected on QCM electrodes, the response will be a result of the total mass of particles; there are no simple methods to discriminate the mass of the two categories without the use of a filter or manipulation during sampling. The QCM response depends on particle dimensions, fundamental resonant frequency, the amplitude of oscillation, and system dissipation properties. In this paper, we study the effects of oscillation amplitude variations and fundamental frequency (10, 5, and 2.5 MHz) values on the response, when particle matter with different sizes (2 µm and 10 µm) is deposited on the electrodes. The results showed that the 10 MHz QCM was not capable of detecting the 10 µm particles, and its response was not influenced by oscillation amplitude. On the other hand, the 2.5 MHz QCM detected the diameters of both particles, but only if a low amplitude value was used.
悬浮颗粒物（PMx）是最重要的环境污染物之一。能够测量和分析 PMx 的微型传感器在环境研究领域至关重要。石英晶体微天平（QCM）是最著名的传感器之一，可用于监测 PMx。一般来说，在环境污染科学中，PMx 分为与粒径相关的两个主要类别（例如，PM < 2.5 µm 和 PM < 10 µm）。基于 QCM 的系统能够测量这个范围内的粒子，但存在一个重要问题限制了其应用。事实上，如果在 QCM 电极上收集不同直径的粒子，那么响应将是粒子总质量的结果；如果不使用过滤器或在采样过程中进行操作，就没有简单的方法来区分这两类的质量。QCM 响应取决于粒子尺寸、基本共振频率、振荡幅度和系统耗散特性。在本文中，我们研究了当不同尺寸（2 µm 和 10 µm）的粒子物质沉积在电极上时，振荡幅度变化和基本频率（10、5 和 2.5 MHz）值对响应的影响。结果表明，10 MHz 的 QCM 无法检测到 10 µm 的粒子，其响应不受振荡幅度的影响。另一方面，2.5 MHz 的 QCM 检测到了两种粒子的直径，但仅当使用低幅度值时。
