Fabrication of high‐density microneedle masters towards the commercialisation of dissolving microneedles

Abstract

Recent progress of dissolving microneedles opens up a great potential for the utilisation of microneedles in a wide range of applications. However, the commercialisation of dissolving microneedles requires mass production of microneedle masters and moulds. In this work, a simple, low-cost and high-throughput fabrication method of high-density microneedle masters is presented. The high-density microneedle masters were fabricated by first machining an aluminium workpiece to form high-density rectangular column arrays using wire-cut electrode discharge machining. Subsequently, the rectangular column arrays were subjected to a chemical etching under a mass-transport limited condition resulting in the formation of conical-shaped microneedle masters without the need of etch mask. For demonstration, the fabricated microneedle masters were used as a template for the fabrication of an inverse polymer mould and subsequently the polymer mould was used for the fabrication of silk microneedles. The proposed method offers a simple, low cost and high throughput means for the mass production of high-density microneedle masters towards the commercialisation of dissolving microneedles.

Current and Future Trends for Polymer Micro/Nanoprocessing in Industrial Applications

“…Consequently, industrial applications of these high-performance, infusible, and insoluble polymers are limited. [66,67] Micro/nano-thermoforming approach can be downsized for smaller dimensions, which is a promising method for the rapid prototyping of nanostructures into polymers. [68] Although μIM can also produce nanostructures with a high replication accuracy, the temperature variation range in thermoforming is less than that required for injection molding, leading to reduced shrinkage during cooling and less residual stress.…”

Conductive Composite Microneedle Sensors Based on Cellulose Acetate Phthalate: Investigating Performance and Biodegradability

“…The design and production of microneedles intended for electrochemical sensing applications has seen a wide variety of strategies adopted and these have been extensively reviewed [6,7]. In most cases, moulds based on PDMS tend to be the replication workhorses and offer an easy route through which to manipulate the material composition of the MN and thereby refine its properties [7][8][9][10][11], This micromoulding approach has obvious advantages for drug delivery applications -providing a simple means through which to incorporate the therapeutic agent, but it has also been shown to enable the production of MN arrays for sensing applications. The potential viability of the approach was initially demonstrated using composite palladium / polycarbonate and nanocarbon/ polystyrene MN structures [12,13].…”

Microneedle array sensors based on carbon nanoparticle composites: interfacial chemistry and electroanalytical properties

“…Microneedle (MN) patches have garnered extensive interest for the transdermal delivery of drugs and vaccines where the small dimensions of the needles penetrating the skin fail to trigger the dermal nerves and offer near painless injection [1][2][3]. A wide variety of approaches have been investigated in the design and construction of the microneedle masters but tend to revolve around the lithography/etching of resist layers on silicon wafers [4][5][6] or the CNC milling of metal blocks (typically aluminium [7][8][9][10]). Lim and colleagues have provided a critique of the approaches taken in microneedle [7,11], but, irrespective of the process taken to acquire the master, the replication workhorse templates are almost invariably produced using PDMS [4,7,8,10,12,13].…”