A Photolithographic Approach to Polymeric Microneedles Array Fabrication

Abstract

In this work, two procedures for fabrication of polymeric microneedles based on direct photolithography, without any etching or molding process, are reported. Polyethylene glycol (average molecular weight 250 Da), casted into a silicone vessel and exposed to ultraviolet light (365 nm) through a mask, cross-links when added by a commercial photocatalyzer. By changing the position of the microneedles support with respect to the vessel, different shapes and lengths can be achieved. Microneedles from a hundred microns up to two millimeters have been obtained just tuning the radiation dose, by changing the exposure time (5–15 s) and/or the power density (9–18 mW/cm2) during photolithography. Different microneedle shapes, such as cylindrical, conic or lancet-like, for specific applications such as micro-indentation or drug delivery, are demonstrated.

Fabrication of a Ti porous microneedle array by metal injection molding for transdermal drug delivery

“…Solid MAs can deliver the drug in three approaches, including “poke and patch”, “coat and poke” and “poke and release” [ 1 , 2 , 28 , 29 ]. Solid MAs were fabricated by various methods, such as lithography and etching [ 30 ], photolithography [ 31 , 32 ], micro molding [ 33 , 34 ], drawing lithography [ 35 , 36 ], micromachining [ 34 ], laser cutting and so on. Solid MAs can be easily mass fabricated at a relatively low cost, but they have no continuity because they can support the delivery of a limited dose of drug, even in the case of “poke and patch” due to the fast closure of the poke pores in skin.…”

Optically monitored drug delivery patch based on porous silicon and polymer microneedles

“…We recently proposed a photolithographic approach to polymeric MNs production that offered several advantages with respect to other micro-fabrication techniques, such as replica molding, laser sculpturing, surface micromachining or three-dimensional printing [ 23 ]. We demonstrated in a systematic study that this technique could allow low-cost fabrication of MNs array with very finely tunable geometric features: shape, length and diameter can be easily changed by properly adjusting the process parameters (lamp power, exposition time, and photolithographic mask) [ 22 ]. The results of the photolithographic fabrication process are summarized in Fig.…”

Polymeric Microneedle Arrays: Versatile Tools for an Innovative Approach to Drug Administration

“…[19][20][21] If the geometry of the system and few process parameters, such as the time exposure and lamp power, are changed, different shapes (cylindrical, conical, or lancet-like) and lengths (from 100 up to 2000 µm) of MNs can be achieved. PEGDA, poured into a silicone vessel and exposed to ultraviolet light (365 nm) through a mask cross-links in the presence of a commercial photocatalyzer.…”

“…based on a single‐step photolithographic process. PEGDA, poured into a silicone vessel and exposed to ultraviolet light (365 nm) through a mask cross‐links in the presence of a commercial photocatalyzer . If the geometry of the system and few process parameters, such as the time exposure and lamp power, are changed, different shapes (cylindrical, conical, or lancet‐like) and lengths (from 100 up to 2000 µm) of MNs can be achieved.…”