Biosensor for human IgE detection using shear-mode FBAR devices

Abstract

Film bulk acoustic resonators (FBARs) have been evaluated for use as biosensors because of their high sensitivity and small size. This study fabricated a novel human IgE biosensor using shear-mode FBAR devices with c-axis 23°-tilted AlN thin films. Off-axis radio frequency (RF) magnetron sputtering method was used for deposition of c-axis 23°-tilted AlN thin films. The deposition parameters were adopted as working pressure of 5 mTorr, substrate temperature of 300°C, sputtering power of 250 W, and 50 mm distance between off-axis and on-axis. The characteristics of the AlN thin films were investigated by X-ray diffraction and scanning electron microscopy. The frequency response was measured with an HP8720 network analyzer with a CASCADE probe station. The X-ray diffraction revealed (002) preferred wurtzite structure, and the cross-sectional image showed columnar structure with 23°-tilted AlN thin films. In the biosensor, an Au/Cr layer in the FBAR backside cavity was used as the detection layer and the Au surface was modified using self-assembly monolayers (SAMs) method. Then, the antigen and antibody were coated on biosensor through their high specificity property. Finally, the shear-mode FBAR device with k t 2 of 3.18% was obtained, and the average sensitivity for human IgE detection of about 1.425 × 10 5 cm 2 /g was achieved.

Film bulk acoustic resonators (FBARs) as biosensors: A review

“…On the other hand, the acoustic wave-based devices are less expensive without compromising their sensitivity. Bulk acoustic wave (BAW) resonators have been widely employed as sensors for detecting variables such as mass García-Gancedo et al 2013;He et al 2011;Mai et al 2004;Nagaraju et al 2014;Rey-Mermet et al 2006), ultra-violet light (Bian et al 2015), infrared light (Wang et al 2011a), ozone (Wang et al 2011b), pressure (Giangu et al 2015), humidity (Zhang et al 2015a), volatile organic compounds (Chang et al 2016;Lu et al 2015), air pollution and biomarkers (Chen et al 2015b;Dickherber et al 2008;Guo et al 2015;Tukkiniemi et al 2009;Weber et al 2006;Wingqvist et al 2008) owing to their high sensitivity, real-time detection, label-free and wireless capabilities (Voiculescu and Nordin 2012). Table 1 compares the mostly reported technologies used in biosensors.…”