Minimally invasive clinical monitoring and data transference in cardiac patients

Baczkowski, Emma 2022. Minimally invasive clinical monitoring and data transference in cardiac patients. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

'Wet' electrodes used in electrocardiography (ECG), are applied to the surface of the skin to record cardiac activity. Over time, water-based electrolytic gels between the electrodes and skin dehydrate, reducing signal quality. Microneedle-electrodes negate the need for conductive gels and potentially improve signal fidelity by circumventing the stratum corneum and contacting the underlying conductive epidermal layers. This thesis aimed to assess the wearability and functionality of microneedle-electrodes in cardiac signal acquisition. Epoxy, 500μm-length microneedles were applied to excised skin models to assess insertion performance. Increasing downward application force increased microneedle penetration efficiency from 79%±8.20 (5N) to 87%±13.32 (15N). The microneedle application technique also had an impact on penetration efficiency, with impact insertion (93%±5.75) proving more effective than manual downward force (71%±22.01). Metallised versions of the epoxy microneedles were integrated into a commercial electrode and compared to conventional wet electrodes in human volunteers. Wet electrodes recorded higher quality signals than microneedle-electrodes in healthy human participants (1.6dB difference between the electrode types). This clinical data informed the development of an in vitro laboratory skin model to assess the influence of microneedle-electrode parameters on a simulated ECG signal. Increasing microneedle length from 500μm (25.2dB±3.25) to 600μm (24.3dB±2.31) did not result in a sustained improvement in signal quality (p>0.05). Bespoke second-generation microneedle-electrodes were manufactured allowing an improved signal quality to be maintained over the recording period (17.3dB±2.11 compared to 15.0dB±1.97 for wet electrodes; p>0.05) in the laboratory model. Human participant studies assessed their wearability and functionality. At rest, the metallised epoxy (23.2dB±5.79) and bespoke (22.5dB±7.57) microneedle-electrode performance was comparable to wet electrodes (24.9dB±6.44) (p>0.05). Under active conditions, the signal-to-noise ratio declined for all electrodes and ECG traces highlighted increased motion artifacts. Participants preferred wet electrodes and highlighted seven key wearability themes. Further optimisation of microneedle-electrodes for ECG monitoring is therefore, warranted.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Pharmacy
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	24 May 2022
Last Modified:	10 Jun 2023 02:03
URI:	https://orca.cardiff.ac.uk/id/eprint/149941

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