Publication on AWSensors technology

Analysis, implementation and validation of a Love mode surface acoustic wave device for its application as sensor of biological processes in liquid media

Authors: Rocha-Gaso, M.I.; Jiménez Y. and Francis, L.

Publisher: Universitat Politècnica de València, 2013

Comparison between High Fundamental Frequency Quartz Crystal Microbalance and Love Mode Surface Acoustic Wave devices in the detection of Carbaryl pesticide

Authors: J.V. García, M.I. Rocha, C. March, P. García, L.A. Francis, A. Montoya, A. Arnau, Y. Jiménez

Event: Acoustic Sensors in analytical and Biophysical Studies, 29-30 August 2013, IMBB-FORTH, Heraklion, Crete.

 

In this work two acoustic technologies: High Fundamental Frequency Quartz Crystal Microbalance (HFF-QCM) and Love Mode Surface Acoustic Wave (LM-SAW) have been compared for the detection of Low Molecular Weight (LMW) compounds in terms of Sensitivity and LOD. The results have also been compared with those obtained with other techniques: Traditional QCM, Surface Plasmon Resonance (SPR) and Enzyme-Linked ImmunoSorbent Assay (ELISA). Carbaryl pesticide was chosen as model analyte because it had been used as a reference LMW compound by those mentioned techniques.

AWS-A10 research platform (AWSensors, Spain) was used to perform the experiments. This platform allowed for a comparison of both devices measured by the same characterization system under similar experimental conditions.

The results achieved with LM-SAW and 100Mhz HFF-QCM were in the same order of magnitude. The achieved value sensitivity (I50 value) and LOD (I90 ) were around 0.31 µ/L and 0.09 µ/L, respectively, for LM-SAW device, and around 0’66 µ/L and 0’14 µ/L, respectively, for HFF-QCM device. Sensitivities and LODs with these novel developments on acoustic technologies improve SPR and traditional QCM technologies, and approach ELISA’s ones.

Review the poster about this experiment by clicking here:

Póster about AWS-HFF sensors for detection of Carbaryl pesticide showed at Crete 2013

 

Advanced, high sensitivity QCM piezoelectric immunosensors for pesticide analysis, based on the measurement of phase changes at high fundamental frequency (HFF)

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

Event:  8th MGPR International Symposium of Pesticides in Food and the Environment in Mediterranean Countries. Cappadocia,  Turkey (2013)

 

The detection of very small mass changes by means of the Quartz Crystal Microbalance (QCM) is a very popular transduction technique in biosensor design for analytical applications. In fact, QCM biosensors for pesticide analysis in fruit and derived products have recently been reported. Despite their interesting analytical performance, these biosensors still need a thorough optimization of several essential analytical parameters. In particular, sensitivity and limit of detection should be significantly improved, so that pesticide biosensors could extend their applicability to more demanding applications, such as the analysis of drinking water. In order to overcome these limitations, a new concept of piezoelectric biosensor is proposed. Unlike classic QCM, where frequency changes are detected as the response to small mass changes, the new biosensor is based on the detection of phase changes, working at high constant frequency (high fundamental frequency: HFF). On this basis, a new 100 MHz QCM immunosensor based on monoclonal antibodies for pesticide analysis has been developed. A completely new device including a dedicated PEEK chip support to attach the HFF functionalized crystals, the automatic injection system, and the electronic characterization system, has been designed and built. Carbaryl and Thiabendazole were chosen as model pesticides to assess the immunosensor performance. Specific monoclonal antibodies were used as biorecognition molecules, working in competitive immunoassays in the conjugate-coated format. Specific hapten conjugates were covalently attached to the gold surfaces of the sensor electrodes by alkanethiol self-assembled monolayers (SAM). As compared to the previous low-frequency QCM immunosensors, the sensitivity was improved by more than a one order of magnitude (I50 values in the sub-µg I-1 range), whereas the limits of detection improved by around two orders of magnitude (LODs around 0.16 µg I-1). Immunoregent consumption was decreased by 5 times (antibody) and 1000 times (assay conjugate). The high sensitivity reached by these immunosensors allows pesticide analysis at concentrations near the European MRLs for drinking water.

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

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

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

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

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.

Development of a Mass Sensitive Quartz Crystal Microbalance (QCM)-Based DNA biosensor using a 50 MHz electronic oscillator circuit

Authors: G. García-Martínez, E. Bustabad, H. Perrot, C. Gabrielli, B. Bucur, M. Lazerges, D. Rose. L. Rodríguez-Pardo, J. Fariña, C. Compère, A. Arnau

Journal: Sensors (2011)

This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm2 in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected.

Read the full article here.

Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications

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

Journal: Review of Scientific Instruments (2011)

 

The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequency/mass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed.

Validation of a phase-mass characterization concept and interface for acoustic biosensors

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

Journal: Sensors (2011)

Acoustic wave resonator techniques are widely used in in-liquid biochemical applications. The main challenges remaining are the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The sensitivity improvement issue has been addressed by increasing the sensor frequency, using different techniques such as high fundamental frequency quartz crystal microbalances (QCMs), surface generated acoustic waves (SGAWs) and film bulk acoustic resonators (FBARs). However, this sensitivity improvement has not been completely matched in terms of limit of detection. The decrease on frequency stability due to the increase of the phase noise, particularly in oscillators, has made it impossible to increase the resolution. A new concept of sensor characterization at constant frequency has been recently proposed based on the phase/mass sensitivity equation: Δφ/Δm ≈ −1/mL, where mL is the liquid mass perturbed by the resonator. The validation of the new concept is presented in this article. An immunosensor application for the detection of a low molecular weight pollutant, the insecticide carbaryl, has been chosen as a validation model.

Read the full article here.