Sharp beveled tip hollow microneedle arrays fabricated by LIGA and 3D soft lithography with polyvinyl alcohol

Abstract

This paper describes a fabrication process of hollow microneedle arrays with a sharp beveled tip for transdermal drug delivery. A master is fabricated through a double deep x-ray lithography process. First, a polymethylmethacrylate (PMMA) sheet is exposed to produce single PMMA parts with a sawtooth profile. The tip angle of each tooth determines the final tip angle of the microneedles. The PMMA parts are assembled and glued on a conductive substrate and then exposed through a second x-ray mask containing an array of hollow triangles as absorbing structures. A metal layer is then electrodeposited around the needles in order to form the future base of the array. A polyvinyl alcohol (PVA) solution is cast on top of the master to form a negative mold of the microneedle array after a low temperature curing and peel-off steps. A liquid PMMA solution is cast on top of the PVA negative mold and after the full PMMA polymerization the PVA is dissolved in water. This fabrication method can be performed in a non-clean room environment and requires little instrumentation. It is therefore compatible with a low-cost mass-fabrication scheme.

Optimizing microneedle arrays for transdermal drug delivery: Extension to non-square distribution of microneedles

“…However, it is realized that since the first fabrication of microneedles a large variety of microneedle distribution have been proposed such as square (Ji et al, 2006;Kim and Lee, 2007), hexagonal (Matriano et al, 2002;Widera et al, 2006), triangular (Perennes et al, 2006) and rectangular (Park et 90 al., 2005). Aggarwal and Johnston (2004) investigated the influence of various patterns (e.g., square, rectangular, etc) on buckling force, bending force and bending stress.…”

Chemical and Physical Enhancers for Transdermal Drug Delivery

“…The methods that have been adopted for microneedle fabrication include wet etching, deep reactive ion etching (DRIE) (Teo et al, 2005), microinjection moulding (Sammoura et al, 2007), isotropic etching, isotropic etching in combination with deep etching and wet etching respectively, dry etching, isotropic and anisotropic, photolithography, thin film deposition (Moon & Lee, 2003), laser cutting (Martanto et al, 2004), and inclined LIGA process (Perennes et al, 2006). Studies have shown that factors such as microneedle geometry, coating depth on solid microneedle and skin thickness affect the drug delivery efficiency using microneedles (Al-Qallaf et al, 2009a;2009b).…”

Innovative Strategies for Enhancing Topical and Transdermal Drug Delivery

“…15) are manufactured based on etching methods used by the microelectronics industry to create arrays of micron-sized needles [214,215]. The majority of studies to date have used silicon or metal MNs, although devices have also been made from dextrin [216,217], glass [218], maltose [219,220], and various polymers [221][222][223][224]. MNs can be made of varying length, as short as 25 m and as long as 2000 m. In addition, base diameter of the needle and needle density can also be altered.…”