Transdermal drug delivery: Microfabrication insights

Iliescu, Ciprian; Chen, Bangtao; Wei, Jie; Yue, Zhilian

doi:10.1109/smicnd.2009.5336568

Cited by 2 publications

(1 citation statement)

References 34 publications

(26 reference statements)

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“…This asymmetric notch is interesting, and probably the result of the properties of a charged, angled layer [184]. Essentially the incoming ions are no longer deflected to both sides equally, but follow the existing topography of the stop layer.…”

Section: Process Integration: Bevel and Borementioning

confidence: 99%

Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures

Bolton¹

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Microneedles are an area of growing interest for applications in transdermal delivery. Small, minimally invasive medical or cosmetic devices, microneedles are intended to penetrate the skin's outer protective layer (stratum corneum) to facilitate delivery of active formulations into the skin. Delivery of solution via microneedles has the benefits associated with hypodermic injection, i.e. avoiding the first-pass metabolism systems, with the added advantages of painless delivery and dose sparing from the reduced solution volumes required.Advancements in semiconductor processing technologies and equipment have enabled the creation of devices and structures that could not have been fabricated in the past. This is also true for the fabrication of microneedles, where previous manufacturing methods have relied on hazardous chemicals such as Hydrofluoric Acid and Potassium Hydroxide to create the sharp tip of the needle, required to reduce insertion force.In this thesis, the realisation of a hollow bevelled silicon microneedle fabricated using only plasma processing techniques is presented, providing a route to scalable manufacture of high-performance, sharp-tipped microneedles. The microneedle fabrication process consists of three main etch steps in the process flow to create hollow structures. For each of the Bevel, Bore, and Shaft processes the development and optimisation is detailed. Throughout the process development, several unexpected processing issues were encountered, including depth non-uniformity, "notching", and "silicon grass". Investigations have been performed to determine the root cause of each issue and fine-tune processes to optimise the final devices. A discussion of the process hardware is also presented, with reference to the benefits for each specific application process.Following development and optimisation of each individual process, the Bevel, Bore, and Shaft processes were integrated in the manufacturing flow to create the final hollow silicon microneedle device. Issues arising from the combination of the three processes have been investigated, resolved, and optimised. This includes the conception and execution of a novel process for the plasma smoothing of an angled silicon surface, which improved the quality of lithography on the non-planar bevel surface and minimised grass formation.Preliminary testing, undertaken to assess the suitability of these devices for transdermal use, included mechanical fracture force, skin penetration, and injection testing. The microneedles were found to be strong enough to remain intact during insertion, and demonstrate successful penetration and injection through the stratum corneum and into the deeper skin layers.

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Section: Process Integration: Bevel and Borementioning

confidence: 99%

Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures

Bolton¹

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Tailoring Porous Silicon for Biomedical Applications: From Drug Delivery to Cancer Immunotherapy

et al. 2018

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In the past two decades, porous silicon (PSi) has attracted increasing attention for its potential biomedical applications. With its controllable geometry, tunable nanoporous structure, large pore volume/high specific surface area, and versatile surface chemistry, PSi shows significant advantages over conventional drug carriers. Here, an overview of recent progress in the use of PSi in drug delivery and cancer immunotherapy is presented. First, an overview of the fabrication of PSi with various geometric structures is provided, with particular focus on how the unique geometry of PSi facilitates its biomedical applications, especially for drug delivery. Second, surface chemistry and modification of PSi are discussed in relation to the strengthening of its performance in drug delivery and bioimaging. Emerging technologies for engineering PSi-based composites are then summarized. Emerging PSi advances in the context of cancer immunotherapy are also highlighted. Overall, very promising research results encourage further exploration of PSi for biomedical applications, particularly in drug delivery and cancer immunotherapy, and future translation of PSi into clinical applications.

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Transdermal drug delivery: Microfabrication insights

Cited by 2 publications

References 34 publications

Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures

Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures

Tailoring Porous Silicon for Biomedical Applications: From Drug Delivery to Cancer Immunotherapy

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