Un nuevo concepto de inmunosensor piezoeléctrico (QCM) para plaguicidas basado en la detección de cambios de fase a alta frecuencia

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Inmunosensor piezoeléctrico de alta sensibilidad.

Authors: A. Montoya, J.V. García-Narbón, A. Sánchez, A. Arnau, Y. Jiménez, C. March

Event: Ibersensors 2012. Puerto Rico (2012)

 

Para resolver las limitaciones de sensibilidad asociadas a los biosensores QCM basados en la detección de pequeños cambios de frecuencia, se propone un nuevo concepto de biosensor piezoeléctrico. El nuevo biosensor se basa en la detección de cambios de fase, trabajando a frecuencia alta y constante. Sobre esta base, se ha desarrollado un inmunosensor QCM de 50 MHz para la determinación de plaguicidas con alta sensibilidad.

Consulta el trabajo completo presentado en este Congreso aquí.

High-sensitivity piezoelectric immunosensor for pesticide analysis

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Authors: J.V. García, C. March, A. Sánchez, Y. Montagut, Y. Jiménez, A. Montoya, A. Arnau

Event: Biosensors 2012, 22 World Congress on Biosensors. Cancún, México (2012)

 

A 50 MHz quartz crystal microbalance (QCM) immunosensor has been developed for the determination of pesticides. High fundamental frequency (HFF) inverted mesa quartz crystal resonators were used. To provide mechanical stability and robustness quartz crystal resonators were attached permanently to a PEEK chip holder. This also allowed easy manipulation in all experimental processes. An automated flow injection analysis system was developed. The system consists of: the flow cell for the sensor chips; a flow circuit with automated syringe pumps, distribution and injection valves; and an electronic characterization system, based on the phase mass measurement at constant frequency. Carbaryl pesticide was chosen as a model analyte. Due to the low molecular weight of this insecticide, the immunoassay format chosen was a competitive one, with monoclonal antibodies (MAbs). The hapten conjugate was covalently immobilized, via mercaptohexadecanoic acid (MHA) self assembled monolayer (SAM), onto the sensor electrode surface. The immunosensor results showed an improvement of one order of magnitude in terms of sensitivity (I50 ≈ 2 μg/L) and two orders of magnitude in terms of limit of detection (LOD < 0,2 μg/L), compared with results obtained with standard 10MHz QCM sensors previously reported by our group. The automated analysis system allowed a very good reproducibility of measurements. Further improvement in terms of sensitivity and limit of detection could be easily accomplished working with higher fundamental frequency sensors (100-150 MHz), which can be directly used with the developed system.

User-friendly Love wave flow cell for biosensors

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Authors: M.I. Rocha-Gaso, J.V. García, L. El Fissi, L. Francis,  A. Arnau, Y. Jiménez, C. March, A. Montoya

Event: Biosensors 2012, 22 World Congress on Biosensors. Cancún, México (2012)

 

Love wave (LW) sensors have attracted a great deal of attention in the scientific community during the last decade, due to its high sensitivity in liquid media compared to traditional quartz crystal microbalance (QCM)-based sensors. However, one of the main issues when dealing with LW-based biosensors is the fluidic aspect, since the surface on top of the Interdigital transducers (IDTs) has to be isolated from liquids. A user-friendly flow cell for LW biosensors was fabricated and tested. The fabricated cell allows a fast and easy installation and replacement of the sensor. Friendly-usability and robustness are two central features of the fabricated LW flow cell. Mechanical, thermal, electrical and chemical requirements are considered. In order to test the cell, a LW immunosensor for the detection of pesticides, using carbaryl insecticide as a model analyte, was implemented. An AT-cut quartz Z propagating /SiO2 LW sensor with λ = 40 μm and 120 MHz center frequency was specifically designed and fabricated for the flow cell. The sensor does not need to be wire bonded, which is a great advantage over previous reported LW sensor setups. The sensitivity, specificity and reusability achieved with this LW immunosensor is discussed and compared to the same immunosensor carried out on a QCM-based technique.

 

Optimization of lateral field excited platform for liquid sensing applications

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Authors: J. Fochtmann, C. Peters, R. Fernández, R. Lucklum, D. McCann, J. Vetelino, A. Arnau

Journal: Sensors and actuators B: Chemical (2012)

 

Investigating the electrical sensitivity of lateral field excited resonators (LFE) we observed two characteristics to highly impact sensitivity. First, an increase of the piezoelectric coupling factor k enhances the viscosity measurement range. Higher coupling factors are provided by the use of new materials, namely lithium tantalite (LiTaO3) and lithium niobate (LiNbO3) with coupling factors of 0.43 and 0.91 respectively. Since the sensitivity to electrical load parameters is governed by relative permittivity of the resonator material itself, the sensitivity to electrical parameters is found to decrease for new materials. Second, an electrode pattern that reveals higher energy trapping in the center of crystal was investigated. Compared to common LFE pattern, a third electrode was introduced in center between bite wing electrodes. Finite element modeling in ANSYS© shows enhanced sensitivity to low relative permittivity in range from 1 to 8. We performed experiments to verify the simulation results. Although an increased frequency shift compared to common LFE resonators was not observed, significantly higher conductance amplitudes occurred, which enhances the measurement range to high viscosity liquids, too.