E-Thesis 51 views 18 downloads
The Characterisation and Development of Silicon Microneedle / MEGAN MCNAMEE
Swansea University Author: MEGAN MCNAMEE
-
PDF | E-Thesis – open access
Copyright: the author, Megan Jessica McNamee, 2026. Distributed under the terms of a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).
Download (149.75MB)
DOI (Published version): 10.23889/SUThesis.71905
Abstract
Oral drug delivery is widely regarded as the ideal administration route due to its ease of manufacture, storage stability, and high patient compliance. In many clinical instances, however, it proves unsuitable due to the hepatic first pass metabolism, which significantly reduces drug bioavailability...
| Published: |
Swansea
2026
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | EngD |
| Supervisor: | Arora, H., Guy, O., and Ashraf, H. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa71905 |
| Abstract: |
Oral drug delivery is widely regarded as the ideal administration route due to its ease of manufacture, storage stability, and high patient compliance. In many clinical instances, however, it proves unsuitable due to the hepatic first pass metabolism, which significantly reduces drug bioavailability and therapeutic efficacy. In response, microneedles (MNs) have garnered increasing attention from public and research sectors, offering painless administration and dose-sparing potential.Silicon MNs were the first devices developed for minimally invasive drug delivery, and recent advances in semi-conductor processing have made their scalable production increasingly feasible. This research aimed to establish evidence for their effective and safe use by characterising their mechanical, biological, and functional performance.Devices were fabricated at 100 mm wafer scale, with process optimisation focused on improving yield and structural fidelity. Devices were produced at heights up to 600 µm with good feature fidelity and yields reaching 82 %. Insertion mechanics were evaluated using digital image correlation (DIC), enabling comparison of strain profiles between MN and hypodermic insertion - the latter served as the clinical gold standard. Over the imaged period, hypodermic needles exerted approximately fourfold greater strain than MNs, indicating the potential for reduced tissue trauma.Biocompatibility of both the silicon substrate and fabricated devices was confirmed using ISO 10993-5 compliant cytotoxicity assays, with no statistically significant impact on the viability of human immortalised keratinocytes. To assess repeatability, dye-based injections into dermal mimics were performed, demonstrating consistent bolus formation and reproducible diffusion. MN injection plumes were uniform in size and morphology, in contrast to the variability observed with hypodermic delivery.To improve compatibility with continuous industrial manufacturing, etch steps were optimised at 150 mm wafer scale, which, when combined with the redesigned layout, resulted in a 140 % increase in usable device die. This research addressed key gaps in silicon MN literature, including fabrication throughput, potential cytotoxicity, and performance benchmarking. Furthermore, this work developed a standardised methodology for device performance assessment and demonstrated feasibility for the scaled manufacture of both hollow and solid silicon MNs. |
|---|---|
| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Microneedles, silicon, semi-conductors, skin model, strain |
| College: |
Faculty of Science and Engineering |
| Funders: |
COATED M2A funding from KLA, the European Social Fund via the Welsh Government
(c80816), and the Engineering and Physical Sciences Research Council |