Gravimetric biosensor based on a 1.3 GHz AlN shear-mode solidly mounted resonator

Abstract

We investigate the performance of solidly mounted resonators based on Ir/tilted-AlN/Ir piezoelectric stacks as biosensors. These films are deposited by varying the pressure, the cathode power and the temperature of a two-step process based on depositing (00 2)-til ted AIN active layers over an (10 3)-oriented AIN seed layer. To minimize the influence of the temperature coefficient of frequency on the stability of the biosensor, we use insulating acoustic mirrors made of layers of Si0 2 and amorphous TaO x with non-\/4 thicknesses, which enables to reduce the TCF to-14 ppm/°C. The mass loading of the resonators with SÍO2 thin films results in a sensitivity of 1800 kHz/pg cm 2. Surface functionalization consists on the binding of silane groups on plasma oxidized SÍO2 surfaces. After a glutaraldehyde link, streptavidin is bonded to the surface to receive biotinylated receptors for several species. We test thrombin-binding aptamer (TBA29 against thrombin, and IgG antibody against immunoglobulin). The sensors response to species of different molecular weight like TBA-29 (9.75 kDa) or IgG antibody (150 kDa) is monitored. Finally, we assess the response of the biosensors to different thrombin concentrations (ranging from 4 nM to 270 nM) on surfaces functionalized with the TBA29 aptamer.

Gravimetric sensors operating at 1.1 GHz based on inclined c-axis ZnO grown on textured Al electrodes

“…This Δ f r corresponds to a mass surface density of 1.3 ng/cm 2 of the biotin conjugated Rabbit IgG. The binding of the biotin conjugated antibodies to the streptavidin receptors is completed in a longer time (~600 s) than reported elsewhere: the time to saturate the functionalized surface depends on the microfluidic arrangement and in this case an open system is used 30 . This experiment is carried out in a temperature controlled room to ensure that the Δ f is caused primarily by the mass attachment; it is also observed that the ZnO gradually reacts with the buffers, and after long immersion in liquids the surfaces are etched away.…”

Integration and Bio-Functionalization of Vertically Aligned Carbon Nanotube Forests on High Frequency AlN Gravimetric Sensors

“…AlN films with tilted grains are deposited in order to excite the shear modes required for the in-liquid operation of the SMRs. These are sputtered though a two-step process [3] in an ultra-high-vacuum system by bombarding a high purity 150 mm Al target with an Ar/N2 (40:60) gas mixture. First an AlN seed layer is grown at high pressure (0.66 Pa).…”

“…This is because they are label free, fast to analyze and their high frequency operation results in a high sensitivity [1]. In particular, thin film electroacoustic resonators based on AlN piezoelectric layers have demonstrated good performance as biosensors [2,3]. Increasing the effective surface area of a resonator without modifying the electrical contact area increases its sensitivity and reduces its response time.…”

Integration of Graphene on AlN Based High Frequency Resonators and Their Functionalization for Biosensing

“…The active surface was located (a) in a microfluidic system to incubate it with the binding buffer containing the target to be detected [3]. A LabVIEW application was used to accurately track the resonant frequency during the biosensing process by detecting the frequency at which the real part of the admittance peaks.…”