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

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• 作者：Mario DeMiguel-Ramos¹Author Vitae ; Bá ; rbara Dí ; az-Durá ; nAuthor Vitae ; José ; -Miguel EscolanoAuthor Vitae ; Mariano BarbaAuthor Vitae ; Teona MireaAuthor Vitae ; Jimena OlivaresAuthor Vitae ; Marta ClementAuthor Vitae ; Enrique Iborra ; ^{eiborra@etsit.upm.es" class="auth_mail" title="E-mail the corresponding author}Author Vitae
• 关键词：Gravimetric biosensor ; Shear mode AlN resonators ; Surface functionalization ; Sensor sensitivity
• 刊名：Sensors & Actuators: B. Chemical
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：239
• 期：Complete
• 页码：1282-1288
• 全文大小：1450 K

文摘

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)-tilted AlN active layers over an (10·3)-oriented AlN 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 SiO₂ and amorphous TaO_x with non-λ/4 thicknesses, which enables to reduce the TCF to −14 ppm/°C. The mass loading of the resonators with SiO₂ thin films results in a sensitivity of 1800 kHz/pg·cm². Surface functionalization consists on the binding of silane groups on plasma oxidized SiO₂ 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.