Ruby Summers

Biomedical Engineering

Year of study:

5th

Looking to Nature: Designing and Manufacturing a Spider-inspired Stethoscope

Abstract

Cardiovascular Disease (CVD) is a leading factor in global mortality. In Glasgow alone 4951 people died between 2019-2021 due to these diseases. Usually, the first point of contact in detection and diagnosis of these diseases is using a traditional stethoscope. The stethoscope design remains almost identical to the device designed by René Laënnec in 1816. A large issue with the traditional stethoscope is that its output is a simple auditory sound. This makes it unsuitable for deaf or hard of hearing medical professionals and does not allow multiple people to listen simultaneously. A piezoelectric stethoscope with a synchronous digital output would provide a solution to these problems and could even be used to continuously monitor patients remotely. These stethoscopes operate by transforming sound signals from the body into an electronic output. Currently the quality of a piezoelectric stethoscope’s output is limited by factors such as environmental noise making it difficult to implement in loud settings such as in the back of an ambulance. To counteract these issues a novel piezoelectric sensor was manufactured and rigorously tested. The device mimicked the strain sensing lyriform organ of spiders. Micro-computed tomography (µCT) played an instrumental role in this project as it enabled the visualisation and dimensional measurements of the lyriform organ which was used in the sensor design. The fabrication process involved masked stereolithography (mSLA) 3D printing combined with salt leaching, with additional investigations into the incorporation of additives like Barium Titanate. Experimental results unequivocally showed that all membrane designs showed responses through the direct and indirect piezoelectric effects. Overall, this project demonstrated a novel protocol for synthesising flexible, porous sensors that displayed piezoelectric behaviours with d33 coefficients of up to 91.73 pm/V. Once refined, these sensors have the potential to aid auscultation in high noise environments.

[1] B. H. Wilson and K. K. Poh, “Addressing the Global Burden of CVD Through ‘ACCelerated’ Action,” Journal of the American College of Cardiology, vol. 81, no. 25, 2023, doi: 10.1016/j.jacc.2023.05.01.

[2] P. Deng, Y. Fu, M. Chen, D. Wang, and L. Si, “Temporal trends in inequalities of the burden of cardiovascular disease across 186 countries and territories,” Int J Equity Health, vol. 22, no. 1, 2023, doi: 10.1186/s12939-023-01988-2 [3] https://www.bhf.org.uk/what-we-do/our-research/heart-statistics/heart-statisticspublications/cardiovascular-disease-statistics-2023

Bio

Ruby Summers is a final Biomedical Engineering student at the University of Glasgow. She is from Falkirk which has a claim to 'fame' through the Kelpies, UFO sightings and the Falkirk wheel. Her external project was at the University of Strathclyde where she spent six months studying spiders, investigating various 3D printing techniques, and coming up with stethoscope designs. She has always had an interest in solving problems in a creative manner and really values the interdisciplinary nature of the LTAX talks. At her placement, her colleagues ranged from physicists, computer scientists, biologists to engineers and this provided an environment where collaboration flourished, and thinking outside the box was commonplace. Her interests lie in Biosensors and Diagnostics, as she feels strongly that prevention and early detection of disease is equally important as the cure.