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Biosensor

Biosensor Application Note

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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You can download the full Application Note in pdf file from this link or download it from our Applications Web Page where you can find this and the rest of our Application and Technology Notes.

QCMD

QCMD New Technology Note

June 3rd 2020: AWSensors is pleased to announce the release of its new Technology Note on Quartz Crystal Microbalance with Dissipation entitled “AWSensors QCMD“.

Summary of the Note

Advanced Wave Sensors is a company that designs, develops, and manufactures ultra-sensitive sensing systems based on the quartz crystal microbalance with dissipation (QCMD) measurement technology. In this Note the technology basics are explained.

QCM-technology

Introduction

At the core of the QCMD technology is a piezoelectric resonator, typically made of quartz, that is excited to oscillate at its resonance frequency in the thickness-shear mode by applying an alternating current through the electrodes deposited on its surface.

With the resonator oscillating in the thickness shear mode, its two surfaces move in the opposite directions, as indicated by the arrows in Figure 2. The wavelength of the shear wave, λ, is therefore twice the thickness of the sensor, ? = 2? . Because ?? = ? , where ? = √(??/??) , is the speed of shear sound in the material and ? is the frequency, the resonance frequency of such a resonator is given by ?? = ??/2? = (?/2?) √(??/??), where ?? is the shear modulus of quartz, ?? is its density, and ? is the (odd) overtone order. The same expression may be derived formally by solving the equations describing the propagation of shear waves in elastic media subject to appropriate boundary conditions, as discussed in ref. 1. Plugging in 29×109 Pa for the shear modulus of AT quartz and 2650 kg/m3 for the density, one obtains a frequency of ~ 5 MHz for a thickness of ~ 330 um at the fundamental, where n = 1.

Continue reading downloading the full Technology Note (below) …


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You can download the full Technology Note in pdf file from this link or download it from our Technology Web Page where you can find this and the rest of our Technology Notes.

SLB

Lipid Bilayers New Application Note

May 15h 2020: AWSensors is pleased to announce the release of its new Application Note on Supported Lipid Bilayers (SLB) entitled “Supported Lipid Bilayer formation followed at low- and high-fundamental frequencies“.

Summary of the Note

The process of supported lipid bilayer (SLB) formation from adsorbed liposomes is a robust biophysical system that is used in laboratories all over the world. Here, it is used to test AWSensors Quartz Crystal Microbalance with Dissipation measurement (QCMD) equipment and high fundamental frequency QCMD sensors. It is shown that the AWSensors QCMD system correctly and quantitatiely reports the frequency and dissipation changes associated with the SLB formation on high- and low-fundamental frequency SiO2-coated sensors. Some differences between the two types of sensors are highlighted. SLB

Introduction

Quartz crystal microbalance with dissipation measurement, or QCMD, has become a popular technique for research in such disparate fields as material science, biophysics, electrochemistry, and immunosensing. [1] One of the reasons for the wide range of applicability and popularity of QCMD is its ability to provide information about molecular organization (topology and geometry) at solid/liquid interfaces. Specifically, it was shown how the combination of frequency and dissipation could distinguish between different surface-immobilized lipidic assemblies: adsorbed liposomes and supported lipid bilayers (SLBs; Figure 1).[2] This allowed the process of SLB formation from liposomes on SiO2-coated QCMD sensors to be followed in situ.[2] Subsequent studies further showed how the combination of frequency and dissipation measurements on various overtones could be used to study adsorbed liposome deformation [3,4] and detect mutations through the analysis of DNA conformation and length. [5, 6]

Continue reading downloading the full Application Note (below) …


Download Full Application Note

You can download the full Application Note in pdf file from this link or download it from our Applications Web Page where you can find this and the rest of our Application and Technology Notes.