Localized and distributed mass detectors with high sensitivity based on thin-film bulk acoustic resonators

Abstract

A mass sensor based on thin-film bulk acoustic resonator, intended for biomolecular applications, is presented. The thin film is a ͑002͒ AlN membrane, sputtered over Ti/ Pt on a ͑001͒ Si wafer, and released by surface micromachining of silicon. Two experiments are proposed to test the mass sensing performance of the resonators: ͑a͒ distributed loading with a MgF 2 film by means of physical vapor deposition and ͑b͒ localized mass growing of a C / Pt/ Ga composite using focused-ion-beam-assisted deposition, both on the top electrode. For the distributed and localized cases, the minimum detectable mass changes are 1.58ϫ 10 −8 g/cm 2 and 7 ϫ 10 −15 g, respectively.

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

“…To solve this issue, we can adopt a localized sensing method [17]. If we punch a hole at the center of the device in the two reflection layers, the little center area of the top electrode (TE) can be accessed, which is highly sensitive to mass variations.…”

P2G-1 Effect of Nonuniform Loading Layer on Monolithic Thickness-Mode Piezoelectric Filters

“…Two special cases have been widely studied. In one case, where the loading element is very small in area or mass, a small shift in the frequency can be detected and this behavior has been used in mass sensing applications [3]. In another case, loading is uniform on the surface of the resonator, and the shift can be calculated by Mason's model [4,5].…”

12E-1 Accelerometer Based on Thin-Film Bulk Acoustic Wave Resonators

“…By means of the piezoelectric properties of the thinfilm acoustic layer and the mass-loading effect, the FBAR experiences a resonance-frequency shifting due to external forces. FBAR-based sensors as, for example, a DNA and protein detector [1], a gas sensor [2], a mercury-ion detector [3], and a localized-mass detector [4][5] achieve improved sensing performance, when compared to other MEMS technologies.…”