Objectives To investigate the current commercially available clear aligners related to brands, companies, Google trends, and marketing claims presented on their official websites. Materials and methods A search was conducted in October 2020 to identify the relevant web-based information, using three languages (English, Chinese, and Korean) and search terms “clear aligner”, , , and in four search engines (Google, Bing, Baidu, and Naver) to identify current clear aligner companies. Each company website was reviewed and assessed for its marketing claims. Results A total of 75 clear aligner brands were identified and included in the study, and 280 claims from their official websites were analysed. Most (70.7%) of the companies made claims regarding “aesthetics”, 66.7% made claims regarding “increased comfort”, 58.7% made claims regarding “shorter treatment time”, and 56.0% of the companies made claims regarding “superior material”. Other claims were made regarding their “novel technology”, “superior hygiene”, “tracking Apps”, “remote monitoring”, and “reduced in-office visits”. Of these marketing claims, only 4.5% cited references supporting the company’s website claims; however, the references were mainly derived from internal company research. Conclusions Using three languages (English, Chinese, and Korean), 75 different brands of clear aligners were currently found online. Most of the marketing claims from the clear aligner companies’ official websites were not referenced to quality scientific studies. Clinicians and patients should critically appraise the content of company claims and advertisements.
The purpose of this study was to investigate bulk acoustic resonator (FBAR) devices using ZnO-based film and back cavity. A Mason equivalent circuit model was adopted to simulate the impedance characteristics of FBAR devices. The influence of piezoelectric material thickness, electrode thickness, and resonance area on the impedance characteristics of FBAR devices was analyzed. Structural parameters of the FBAR devices were designed, and bulk silicon micromachining was applied to fabricate Al/ZnO/Al-based FBAR devices with a back cavity. X-ray diffraction analysis shows that ZnO piezoelectric films have a highly preferred c-axis orientation. The frequency response of longitudinal wave FBAR devices has been measured by an RF network analyzer, and the results indicate the series resonant frequency and parallel resonant frequency of the fabricated FBAR devices determined to be 1.546 GHz and 1.590 GHz, respectively, which are close to the simulated results. According to the measured results, the effective electromechanical coupling coefficient and the quality factor have been calculated to be 6.83% and 350, respectively. The findings of this study may serve as reference for the development of FBAR devices. Keywords-back cavity, bulk silicon micromachining, film bulk acoustic resonator, ZnO piezoelectric film I. INTRODUCTION he wireless communication technology has developed rapidly in recent years. Frequencies have increased from 500 MHz to 6 GHz, and the device circuitry has become progressively miniaturized and integrated. As important elements in RF circuits, filters have also had to shrink and integrate. Common surface acoustic wave filters and dielectric ceramic filters in common use no longer meet these requirements. The appearance of thin film acoustic resonator (FBAR) devices has led to their development [1-3]. Featuring high-frequency support, high Q, greater power capacity, and compatibility with CMOS-integrated circuit technology [4-5], FBARs are important devices among next generation filters [6-7]. Design and fabrication of FBAR devices have attracted the attention of manufacturers as design and manufacturing
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