Engineering surface acoustic wave sensing and diagnostic devices

Khalid, Muhammad Arslan (2017) Engineering surface acoustic wave sensing and diagnostic devices. PhD thesis, University of Glasgow.

Abstract

Globally, over 50% of deaths occur due to the top 10 global diseases which include cardiovascular disease, cancer and infectious diseases. Low and middle-income countries (LMICs) are disproportionately affected. 80% of all deaths due to non-communicable diseases occur in low and middle income countries and with numbers on the rise. In these disadvantaged and vulnerable populations, diseases are often detected late. The treatment required is therefore increasingly extensive and expensive. Early detection, treatment and monitoring coupled with life-style changes can reduce mortality and morbidity. Many laboratory and clinical diagnostic tests have been developed. However, in order to provide healthcare in resource poor areas near the patient side (point-of-care), portable and low-cost bioanalytical assays are required. Lab-on-a-chip technology has emerged as a contender for point-of-care testing and monitoring but due to the complexity of the systems, there has been limited success in miniaturisation of fully integrated assays.
This thesis takes a new approach to make use of existing and readily available mobile technologies to engineer on-chip, integrated, portable and low-cost microfluidic platforms using surface acoustic waves (SAW). The ability of SAW to manipulate fluids has been used to develop therapeutic and sensing devices.
In the first application, SAW acoustic streaming was used to mechanically ‘clot’ or ‘solidify’ a droplet of human whole blood containing anti-coagulants in as quickly as 6 seconds. To analyse this mechanical process of a change in state, in small sample volumes, a new method which used light deflection from the surface perturbations was developed which could potentially replace clinical thromboelastography. The higher order acoustic streaming is known to be significantly influenced by a fluid’s viscosity. In a second application, as a proof of concept, it was demonstrated that the drop vibration due to SAW streaming together with the light deflection method can be used to study the relative viscosity response in samples. Furthermore, to aid the development of an integrated digital microfluidics, such as a blood monitoring device, a low cost (~$65) smart-phone based SAW platform prototype has been built using additive manufacturing technologies.
Many lab-on-chip devices rely on optical detection such as microscopes. SAW already have shown promise in fluid manipulation and can eliminate the need for external pumps in sample processing. However, optical detection remains a challenge to create truly point-of-care devices. In this thesis, integration of SAW with portable lens-free microscopy that offers a large field of view (FOV) (~30 mm2) is demonstrated. Furthermore, a new method has been proposed for label-free visualisation of waves in fluids and to study their rheological response by analysing the wave relaxation process. This method can potentially be developed into a high-throughput viscosity sensor for disease diagnostics. Finally, by coupling SAW in transmissive superstrates (a low-cost disposable chip), acoustically tuneable nanolenses were created which allowed the detection of sub-micron particles in liquids without super-resolution techniques. As an application of this technique, detection of herpes simplex virus (type I) has been shown.
In summary, this thesis presents the potential of SAW through its integration with mobile platforms such as a smartphone or lens-free microscope to engineer label-free, low-cost and high-throughput sensing and testing devices.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Surface acoustic waves, SAW, POC, point of care, diagnostics, sensing, smartphones, mobile phone, m-health, optics, acoustics, holography, image analysis, computer vision, lamb waves, ultrasounds, acoustic streaming, droplets, microfluidics, lab on a chip.
• Subjects: Q Science > QC Physics; T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Supervisor's Name: Cooper, Professor Jonathan
• Date of Award: 2017
• Embargo Date: 25 October 2021
• Depositing User: Dr. Muhammad Arslan Khalid
• Unique ID: glathesis:2017-30999
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 08 Nov 2018 16:24
• Last Modified: 07 Jan 2019 10:52
• URI: https://theses.gla.ac.uk/id/eprint/30999