Surface acoustic wave enhanced electroanalytical sensors

Kaplan, Emrah (2015) Surface acoustic wave enhanced electroanalytical sensors. PhD thesis, University of Glasgow.

Abstract

In the last decade, miniaturised “lab-on-a-chip” (LOC) devices have attracted significant interest in academia and industry. LOC sensors for electrochemical analysis now commonly reach picomolar in sensitivities, using only microliter-sized samples. One of the major drawbacks of this platform is the diffusion layer that appears as a limiting factor for the sensitivity level. In this thesis, a new technique was developed to enhance the sensitivity of electroanalytical sensors by increasing the mass transfer in the medium. The final device design was to be used for early detection of cancer diseases which causes bleeding in the digestive system. The diagnostic device was proposed to give reliable and repeatable results by additional modifications on its design.
The sensitivity enhanced-sensor model was achieved by combining the surface acoustic wave (SAW) technology with the electroanalytical sensing platform. The technique was practically tested on a diagnostic device model and a biosensing platform.
A novel, substrate (TMB) based label-free Hb sensing method is developed and tested. Moreover, the technique was further developed by changing the sensing process. Instead of forming the sensitive layer on the electrodes it was localised on polystyrene wells by a rapid one-step process.
Results showed that the use of acoustic streaming, generated by SAW, increases the current flow and improves the sensitivity of amperometric sensors by a factor of 6 while only requiring microliter scale sample volumes. The heating and streaming induced by the SAW removes the small random contributions made by the natural convection and temperature variation which complicate the measurements. Therefore, the method offers stabilised conditions for more reliable and repeatable measurements.
The label-free detection technique proved to be giving relevant data, according to the hemoglobin concentration. It has fewer steps than ELISA and has only one antibody. Therefore, it is quick and the cross-reactivity of the second antibody is eliminated from the system. The additional modifications made on the technique decreased the time to prepare the sensing platform because the passivation steps (i.e., pegylation), prior to structuring a sensitive layer were ignored. This avoidance also increased the reliability and repeatability of the measurements.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Surface Acoustic Wave, biosensor, electrochemistry, mass transport, Lab on a Chip.
• Subjects: Q Science > Q Science (General); T Technology > T Technology (General); T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Supervisor's Name: Cooper, Prof. Jonathan
• Date of Award: 2015
• Depositing User: Mr. Emrah Kaplan
• Unique ID: glathesis:2015-6557
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 20 Jul 2015 09:10
• Last Modified: 20 Jul 2018 11:09
• URI: https://theses.gla.ac.uk/id/eprint/6557