Tag Archive for: SAW

Publication on AWSensors technology

Portable Surface Acoustic Wave device platform coupled with a paper-based capillary fluidics for real-time biosensing applications

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Authors: Angelos Ntimtsas and Electra Gizeli

Journal: Chemical Society Sensors and Actuators A: Physical

Abstract: Surface acoustic wave (SAW) sensors have emerged as prominent real-time, label-free biosensors with diverse applications in immunoassays and nucleic acid detection. However, widespread adoption in diagnostics has been impeded by challenges such as miniaturization of instrumentation, microfluidics fabrication and high attenuation in liquid environments. In this study we address these limitations by presenting a portable platform capable of real-time monitoring of a SAW microarray chip comprising up to four sensing channels, combined with a novel paper-based capillary flow channel. For the fabrication of a portable, automated and versatile sensor platform, we integrated a microcontroller, RF components, and a micropump for flow control. Calibration procedures ensured accurate measurements for both amplitude and phase, with a low drift rate (0.72 mdB/h and 1.00 mdeg./h, respectively) and high resolution (2.10 mdB and 6.10 mdeg.), indicating stable operation with minimal interface electronics. The capillary flow channel, implemented by confining the fluid on the sensing surface using a nitrocellulose strip, facilitated laminar and continuous sample flow with minimum damping of the acoustic signal. The sensor system was evaluated with two SAW devices at 100 and 200 MHz using glycerol dilutions within the range of 1% and 70%, demonstrating real-time monitoring capabilities and linear correlations between amplitude and phase changes. To prove the biosensing and clinical validity of the SAW newly developed system, DNA adsorption on a poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) functionalized SAW-surface was demonstrated with a detection limit of 0.001 μg/mL. Our study demonstrates the feasibility of a portable SAW sensor system coupled with a low-cost and replaceable capillary flow channel for real-time monitoring and biomolecular detection.

The full article can be accessed here.

Tracking Recovery

Tracking Recovery Technology Note

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September 15th 2020: AWSensors is pleased to invite you to take a look to its new Technology Note entitled “Tracking Recovery Technology Note”.

Summary of the Note

Use of the AWSensors X1 Instrument Tracking Recover feature to monitor overtones frequency and dissipation shifts of air-to-liquid medium exchanges onto 5 MHz QCM sensors.

Tracking Recovery

Introduction

The Tracking Recovery feature included in AWSensors X1 platform allows the user to monitor large and fast frequency shifts in QCM (Quartz Crystal Microbalance) admittance spectrum. These sudden modifications in the sensor response are common is some applications where dramatical changes in the viscoelastic properties of the sensor surrounding medium take place.

This technical note illustrates the utility of tracking recovery feature to characterize an air-to-liquid medium exchange. According to Kanazawa and Gordon theory predictions [1], a complex frequency shift is expected in the sensor electromechanical response when the semi-infinite medium placed over the QCM’s top electrode is replaced by other semi-infinite medium. This shift will depend on the viscosity and density properties of the final medium. Following, Kanazawa-Gordon equation is presented for both the frequency (Eq. 1) and the half-bandwidth (Eq. 2) shifts.

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Carbaryl Biosensor based on antibody detection

Biosensor Application Note

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July 3rd 2020: AWSensors is pleased to invite you to take a look to the Biosensor Application Note entitled “Acoustic Biosensor“.

Summary of the Note

An immunosensor application for determination of carbaryl pesticide was developed by using AWS A20 research platform and AWS F20 Fluidic System. Carbaryl was chosen as the model analyte. Two kinds of acoustic sensors were employed: AWS HFF-QCM sensors (50 MHz and 100 MHz) and Love-SAW sensors with appropriate cells. The AWS A20 platform allowed monitoring phase-shift changes at constant frequency as a function of the sensor surface mass changes.

Biosensor

Introduction

Sensor functionalization: Carbaryl hapten conjugate was covalently immobilized by means of Self Assembled Monolayer (SAM).

Immunoassay format: The chosen competitive immunoassay was a binding-inhibition test based on conjugate-coated format. Carbaryl analyte competes against the immobilized hapten-conjugate for Monoclonal Antibodies.

Carbaryl detection: Samples were injected onto the sensors’ surfaces. AWS software allowed controlling sample injection and fluidics. Furthermore, the employed platform allowed performing the measurements at a constant temperature of 25°C ± 0.05°C.

Since analyte inhibits antibody binding to its respective immobilized conjugates, increasing concentrations of analyte are detected by a change in the increment of the phase-shift of the sensor. The following figures present a representative assay cycle selected from a continuous monitoring in a carbaryl determination, for 100 MHz HFF QCM and 120MHz Love Wave Sensors.

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

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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