Tag Archive for: AWS-HFF sensors

Scientific publication

A low-cost microfluidic flow stabilizer for enhancing QCM measurement stability in in-liquid bio-applications

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Authors: Mohamed Adel, Ahmed Allam, Ashraf E Sayour, Hani F Ragai, Shinjiro Umezu and Ahmed M R Fath El-Bab

Journal: Eng. Res. Express

Abstract

Quartz crystal microbalance (QCM) is a powerful sensing technique widely used in various applications, including biosensing, chemical analysis, and material science. In in-liquid applications, QCM measurements are susceptible to fluctuations in fluid flow rate, which can introduce unwanted noise and compromise the accuracy and reliability of the measurements. In this work, we present an approach to enhance the stability of QCM measurements by utilizing a microfluidic flow stabilizer. The flow stabilizer is designed to minimize flow rate fluctuations, thereby reducing the impact of hydrodynamic effects on the QCM frequency response. We employ a comprehensive methodology that combines computational fluid dynamics (CFD) simulations using ANSYS Fluent software, microfabrication, and experimental testing to evaluate the effectiveness of the flow stabilizer in mitigating flow-induced fluctuations and improving the reliability of QCM measurements. For fabrication, we use direct engraving with a CO2 laser beam on polymethyl methacrylate (PMMA) material to drastically reduce the fabrication cost (to <40 cents) and fabrication time (to 35 min) of the microfluidic chip. Two different designs have been presented and tested: one with a single air reservoir and the other with two reservoirs. Two distinct setups employing a peristaltic pump and a micropump, along with a high fundamental frequency of 50 MHz QCM sensor, were utilized for comprehensive testing in this study. The experimental results demonstrated that the first and second designs of the microfluidic flow stabilizer effectively reduced the fluctuation amplitude in QCM measurements from 100% (input) to 23% and 19% (output), respectively.

You can access the full publication here.

Publication on AWSensors technology

Quartz crystal microbalance in soft and biological interfaces

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Authors: Ilya Reviakine

Journal: Biointephases (2024)

 

Abstract


Applications of quartz crystal microbalance with dissipation to studying soft and biological interfaces are reviewed. The focus is primarily on data analysis through viscoelastic modeling and a model-free approach focusing on the acoustic ratio. Current challenges and future research and development directions are discussed.

You may read the full paper here.

A liquid biopsy platform combining a high fundamental frequency QCM device with dynamic chemistry for detecting mutations in circulating DNA

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Authors: A. Grammoustianou, G. Papadakis, M. Tabraue, J.J. Díaz-Mochon, R. Fernández, J.V. García, A. Arnau, E. Gizeli. AWSensors S.L., Institute of Molecular Biology and Biotechnology- FORTH, University of Crete, Destina Genomics S.L., Centro de Investigación e Innovación en Bioingeniería – Universidad Politécnica de Valencia

Event:  5th International Conference on Bio-sensing Technology, Riva del Garda, Italy (2017)

In the past decade, the analysis of circulating tumour DNA (ctDNA) in blood has been a major breakthrough; ctDNA has been proposed as a priceless source for cancer diagnostic, prognostic and treatment monitoring through a new methodology known as “Liquid Biopsy”. This study presents a novel diagnostic method for the acoustic detection of KRAS mutations in ctDNAs based on: (1) DNA analysis by “dynamic chemistry” that utilizes aldehyde modified nucleobases (SMART) and abasic peptide nucleic acids (DGL probes) capable for the errorfree detection of nucleic acids and their mutations; and, (2) a high fundamental frequency (100 MHz) acoustic wave microsensor (AWS HFF-QCM) that allows the accurate, inexpensive, label-free and real time monitoring of the “dynamic chemistry”. Surface-immobilized DGL probes on the AWS HFF-QCM device are used to detect ctDNAs of wild type and mutated KRAS variants. Upon hybridization of the DGL probe with its target ssDNA, a duplex is formed where biotin- tagged SMART bases can lock in front of the position under interrogation; streptavidin binding detected in a follow-up step confirms the presence of the SMART bases. The use of DGL probes in combination with an isothermal DNA amplification step RPA) have allowed the sensitive and specific recognition of single mismatches in KRAS genes in less than 1 hour. This work presents a unique and novel technology that can emerge as a promising tool in the field of cancer diagnostics.

Liquid Biopsy detection protocol

Schema for complete detection protocol:

(A) Extracted DNA containing mutant (red) and wild type DNA fragments (black) are enzymatically amplified.

(B) Denatured amplicons are hybridized on surface immobilized DGL probes. Chemical locking of a specific tagged SMART base takes place only in the appropriate position.

(C) Incorporated SMART bases are recognized by streptavidin and monitored in real-time during an acoustic measurement.