Acoustic biosensing using functionalised microbubbles
type: CreativeWork
description: In this work, functionalised microbubbles are investigated as a new platform for acoustic biosensing. In medical ultrasound, encapsulated microbubbles (MBs) are injected into the body to enhance contrast between blood and surrounding tissue. Microbubbles are not only good ultrasound scatterers: when placed in an ultrasound field, they act as non-linear resonators, generating harmonic energies in the scattered acoustic signal, and this can be further exploited for biosensing. Analytical models and finite element method (FEM) simulations for the interaction between high frequency (1-300 MHz) acoustic waves and encapsulated microbubbles, show that an incident acoustic wave can set a microbubble into mechanical resonance. The resonant frequency is strongly dependent on the shell properties (thickness, elasticity, viscosity, $\textit{etc.}$), and it is affected by a layer of material attaching to its surface. Existing analytical models in the literature cannot predict the change in microbubble resonance when the material properties of the added layer differ to those of the shell. A new model describing the dynamics of encapsulated and functionalised microbubbles is developed and validated in this thesis. The new Rayleigh-Plesset-like equation accounts for the interaction between the functionalisation layer and the encapsulating shell. Complementary FEM simulations predict that the addition of a 100 nm-layer with a low shear modulus, mimicking the attachment of a biological material, to 100 nm-shell thickness silica microbubbles with radii in the range 1.96-2.33 $\mu$m, lowers the resonant frequencies by $\sim$ 10 to 6 MHz. Nearly monodispersed silica-organosilane-silica microbubbles are fabricated with radii in this range, using a core-shell technique. The synthesis method enables excellent control of size distribution and shell thickness of the microbubbles, which can be tailored for maximum resonance in a desired frequency range. An acoustic system has been designed an…
abstract: In this work, functionalised microbubbles are investigated as a new platform for acoustic biosensing. In medical ultrasound, encapsulated microbubbles (MBs) are injected into the body to enhance contrast between blood and surrounding tissue. Microbubbles are not only good ultrasound scatterers: when placed in an ultrasound field, they act as non-linear resonators, generating harmonic energies in the scattered acoustic signal, and this can be further exploited for biosensing. Analytical models and finite element method (FEM) simulations for the interaction between high frequency (1-300 MHz) acoustic waves and encapsulated microbubbles, show that an incident acoustic wave can set a microbubble into mechanical resonance. The resonant frequency is strongly dependent on the shell properties (thickness, elasticity, viscosity, $\textit{etc.}$), and it is affected by a layer of material attaching to its surface. Existing analytical models in the literature cannot predict the change in microbubble resonance when the material properties of the added layer differ to those of the shell. A new model describing the dynamics of encapsulated and functionalised microbubbles is developed and validated in this thesis. The new Rayleigh-Plesset-like equation accounts for the interaction between the functionalisation layer and the encapsulating shell. Complementary FEM simulations predict that the addition of a 100 nm-layer with a low shear modulus, mimicking the attachment of a biological material, to 100 nm-shell thickness silica microbubbles with radii in the range 1.96-2.33 $\mu$m, lowers the resonant frequencies by $\sim$ 10 to 6 MHz. Nearly monodispersed silica-organosilane-silica microbubbles are fabricated with radii in this range, using a core-shell technique. The synthesis method enables excellent control of size distribution and shell thickness of the microbubbles, which can be tailored for maximum resonance in a desired frequency range. An acoustic system has been designed an…
author: Miele, Isabella
language: en
keywords: Acoustic sensing, Microbubbles, Biosensing, Acoustic wave sensing, SAW, Ultrasound, Sensing
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/71998f06-9430-4a98-bb76-78bc98e98d8a/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2020-05-16
date modified: 2026-07-22T22:23:59Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.48889