Ultrasound Transducers for Therapeutic Applications

Lead Research Organisation: University of Glasgow
Department Name: School of Engineering

Abstract

Many trials and studies, both in-vivo and in-vitro, have demonstrated that exposing a fractured bone to Low Intensity Pulsed Ultrasound (LIPUS) accelerates the healing process. Most research involves acoustic fields of similar frequency (typically 1.5 MHz), pulse characteristics and intensities. However, recent research has identified that an ultrasonic field can stimulate cell migration in osteoblasts at both 1 MHz in conventional LIPUS arrangement, and 45 kHz in a continuous wave configuration. This provides some early evidence that it might be possible to deliver therapeutic ultrasound for healing at a frequency typically used in ultrasonic surgical devices. Ultrasonic bone cutting devices for surgery operate in the frequency range 25 kHz - 35 kHz. If LIPUS therapy is effective in this frequency range then it may be possible to incorporate therapeutic capabilities into a bone cutting device.

Although cell migration, is thought to be one of the mechanisms by which LIPUS accelerates bone repair, there is no proven direct link. One research study has established a much stronger link between LIPUS stimulation and the production of COX-2 and PGE2 - substances well known to promote bone formation. Therefore, this project will focus on measuring the concentration of PGE2 to assess potential effectiveness for healing bone.

The aim of this project is to research the potential for an ultrasonic therapeutic healing mechanism to be characterised and delivered at frequencies associated with ultrasonic surgery. Transducer systems will then be designed to operate with combined surgery and therapy capabilities.

The objectives are as follows:

1. Design a range of ultrasonic transducers and driving systems to carry out a comprehensive, direct comparison of the effects of varying the frequency, pulse characteristics and intensity on healing.

2. Demonstrate the efficacy of measuring the concentration of PEG2 in defining effective healing capability of ultrasonic therapy devices.

3. Create prototype ultrasonic devices capable of combined surgery and therapy and conduct lab demonstrations of their performance.

The novelty of the project lies in the investigation of ultrasonic fields (frequency, pulsing, intensity) beyond conventional LIPUS for effective healing especially at low ultrasonic frequencies, and the design, characterisation and demonstration of innovative transducers and prototype devices that combine capability for surgery and healing.

The project is aligned with the EPSRC healthcare technologies theme, offering advances in both ultrasonic surgery and therapy. Ultrasonic devices are being developed for a wide range of bone cutting surgeries, offering advantages of low force and high precision, often allowing surgical procedures to be carried out on an out-patient basis. The project begins the research that could ultimately reduce post-operative recovery times by simultaneously or consecutively enabling precision surgery and accelerated healing in procedures using a single ultrasonic device.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509668/1 01/10/2016 30/09/2021
1805089 Studentship EP/N509668/1 03/10/2016 03/08/2020 Jill Savva
 
Title New culture vessel - the 'biocell' - allowing growth of biological cells and enabling immersion in water tank for exposure to ultrasound without changing the acoustic field 
Description New culture vessel - the 'biocell' - allowing growth of biological cells and enabling immersion in water tank for exposure to ultrasound without changing the acoustic field. The vessel consists of a custom-designed 3D-printed frame bounded on either side by very thin mylar film (from Goodfellow, UK). Funnels on either side of the frame allow the fitting of rubber septa and injection of cells and growth media. Cells are grown on one surface, and the window created by the frame allows the ultrasonic field to pass through the cell layer with very little change to the acoustic field compared with free field conditions (unlike existing similar systems, which are designed primarily for optical transparency). 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? No  
Impact Full details of the culture vessel design will be included in a paper currently being written. It may be adopted for use in ultrasound exposures as part of the EPSRC Ultrasurge project.