## 1 Introduction  
Liquid or solid suspended particles are often present in the atmosphere. PM\({}_{\text{10}}\) can enter the human throat and chest cavity through the nose and mouth; PM\({}_{\text{2.5}}\) can enter the human trachea, bronchi, and alveoli, seriously affecting human health and causing respiratory, cardiovascular, and cerebrovascular diseases [1; 2; 3; 4]. The World Health Organization states that when the annual average mass concentration of PM\({}_{\text{2.5}}\) exceeds 35 \(\upmu\)g/m\({}^{\text{3}}\), the risk of human mortality increases by about 15% compared to the annual average mass concentration of 10 \(\upmu\)g/m\({}^{\text{3}}\)[5]. One of the priorities of air quality monitoring in various countries is to achieve accurate monitoring of the mass concentration of airborne particles such as large coarse particles (LCP, diameter \(\geq\) 10 \(\upmu\)m), PM\({}_{\text{10}}\) (diameter \(\leq\) 10 \(\upmu\)m), and PM\({}_{\text{2.5}}\) (diameter \(\leq\) 2.5 \(\upmu\)m). The mainstream particulate matter monitoring devices include the gravimetric method [6], the tapered element oscillating microbalance (TEOM) method, the \(\upbeta\)-ray attenuation method, and the light scattering method [7]. The gravimetric method has high measurement accuracy, and its data are often used as reference standards and calibration data for automatic monitoring equipment, but it requires manual operation and takes a longer time than other methods [8]. The \(\upbeta\)-ray attenuation method analyzes the particles based on their absorption intensity of the \(\upbeta\)-rays, but the measurement accuracy is usually not high. The light scattering method detects the intensity of the scattered light from the sampled particles to deduce the concentration of the particles, but this method relies on the nature of the particles, and thus, it has relatively low accuracy. Table 1 listed devices based on the above methods. Since the devices manufactured by these methods generally have the disadvantages of being expensive, time-consuming, and bulky, designing and producing highly sensitive, small, and low-cost aerosol particle monitoring devices is one of the goals for researchers. The surface acoustic wave (SAW) is an elasticity acoustic wave traveling along the surface of a material. In 1885, [PERSON] demonstrated the existence of the Surface Acoustic Wave [9]. In 1965, [PERSON] and [PERSON] designed and fabricated the interdigital transducer (IDT) for excitation and detection of the Surface Acoustic Wave [10], laying the foundation for the rapid development of applied research on the Surface Acoustic Wave sensors since the 1970s. SAW sensors have the characteristics of small size, high sensitivity, low cost, and simple signal processing, which are consistent with the development direction of aerosol particulate monitoring equipment. [PERSON] et al. used SAW sensors for fine particle mass monitoring and showed that the sensitivity of the 158 MHz SAW sensor has 266 times the sensitivity of a 10 MHz quartz crystal micro-balance (QCM) sensor [11]. [PERSON] et al. combined the SAW device with a virtual impactor, using the thermophoretic sedimentary method to obtain a miniature personal PM\({}_{2.5}\) monitor with a flow rate of 13.5 mL/min [12]. [PERSON] et al. reported a 3D-printing technology-based virtual impactor for a PM\({}_{1}\) monitor with a 147.24 MHz SAW resonator, and the result shows a sensitivity of 7.446 Hz/min per \(\upmu\)g/m\({}^{3}\)[13]. [PERSON] et al. combined a flow rate of 0.125 LPM cyclone sampler with a 122 MHz shear-horizontal surface acoustic wave (SH-SAW) device, and its sensitivity to cigarette particles reached 9 Hz/ng [14]. [PERSON] et al. designed a QCM particle sensor based on a 3D printed virtual impactor and successfully separated silicon dioxide particles under 8 \(\upmu\)m [15]. All of these studies have demonstrated the potential of mass-sensitive piezoelectric sensors, especially SAW sensors, for environmental particulate detection applications.