Porosity control of polylactic acid porous microneedles using microfluidic technology

Porous microneedle (MN) with interconnected pores inside can penetrate human skin and extract interstitial fluid (ISF) that contains various biosensing analytes such as glucose and antibodies. However, most of the conventional researches on porous MN fabrication are facing the problem of inhomogeneous pores inside the porous structure, which makes it difficult to control the porosity of MN as well as ISF extraction efficiency. In this study, we proposed a novel fabrication of porous MNs by using microfluidic technology. The porous MNs composed of homogeneous microparticles made by microfluidic technology could achieve a porosity-controlled structure inside. Microparticles with diameters ranging from 10 to 30 µm were produced separately and the coefficient of variation was 2-5%, indicating that the prepared microparticles had uniform sizes. Monodisperse PLA microparticles were bonded together with heat treatment to fabricate porous MN array. The porosity of MNs can be adjusted by changing the diameter of microparticles as the pores inside MNs are formed from the voids between bonded microparticles. It is expected that the proposed fabrication method can make a porosity-controllable MN array with homogeneous pores interconnected inside. Thus, fabrication of porous MNs with adjustable ISF extraction efficiency can be realized to fulfill various demands from different fields as well as applications.