No abstract

No abstract

Articles you may be interested inSynthesis and characterization of 10nm thick piezoelectric AlN films with high c-axis orientation for miniaturized nanoelectromechanical devices Appl. Phys. Lett.

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.

ARTICLE INFO ABSTRACTSolidly mounted resonators (SMRs) with a top carbón nanotubes (CNTs) surface coating that doubles as an electrode and as a sensing layer have been fabricated. The influence of the CNTs on the frequency response of the resonators was studied by direct comparison to identical devices with a top metallic electrode. It was found that the CNTs introduced significantly less mass load on the resonators and these devices exhibited a greater quality factor, Q.(>2000, compared to ~1000 for devices with metal electrodes), which increases the gravimetric sensitivity of the devices by allowing the tracking of smaller ~ " frequency shifts. Protein solutions with different concentrations were loaded on the top of the resonators Keywords' Biosensor anc ' me ' r res P onses to mass-load from physically adsorbed coatings were investigated. Results show Carbón nanotube (CNT) tnat resonators using CNTs as the top electrode exhibited a higher frequency change for a given load Aluminum nitride (A1N) (~0.25 MHz cm 2 ng _1 ) compared to that of a metal thin film electrode (~0.14 MHz cm 2 ng _1 ), due to the Bulk acoustic wave resonator (BAW) lower mass of the CNT electrodes and their higher active surface área compared to that of a thin film Gravimetric biosensor metal electrode. It is therefore concluded that the use of CNT electrodes on resonators for their use as gravimetric biosensors is a significant improvement over metallic electrodes that are normally employed.

No abstract

No abstract

No abstract