Application of Ultra-sensitive Pillar-enhanced Quartz Crystal Resonators for Airborne Detection of Nanoparticles: A Theoretical Study

Although quartz crystal resonators (QCR) have been used for airborne detection of particles and viruses, they suffer from various limitations, such as low sensitivity compared to other devices. Therefore, it is necessary to develop a new device capable of achieving high sensitivity, which can be used for practical airborne detections. The current study reports a comprehensive parametric theoretical model for analyzing the response of ultra-sensitive pillar-enhanced QCR (QCR-P) for airborne detection of nanoparticles. The electromechanical model comprised an equivalent circuit integrated with pillars containing nanoparticles. It was shown that pillar height and particle radius play a critical role in the response of QCR-P devices. The study revealed that selecting the optimal pillar height can lead to a significant frequency shift depending on the nanoparticle radius and pillar height, while it is independent of particle mass density. These results underscore the potential of utilizing pillars to substantially enhance the sensitivity of conventional QCR up to 140 times in the airborne detection of nanoparticles. These findings can be utilized to design optimum pillar heights to achieve maximum sensitivity in the airborne detection of nanoparticles and proteins, thereby enabling the adoption of ultra-sensitive pillar-enhanced quartz crystal resonators for practical airborne applications.