Porous microneedles on a paper for screening test of prediabetes

Abstract

Porous microneedles are expected to have a variety of potential for applications in diagnostics owing to their ability to penetrate human skin painlessly and extract bio‐fluid by capillary action. In this paper, a ‘Porous Microneedle on a Paper substrate’ (PMP) is proposed as a novel platform for direct integration of sensors. A microneedle array with height of approximately 840 μm was prepared on a paper. The fabrication process consists of salt leaching and heat press moulding. In this method, the salt particles are utilized as porogen materials. Mixture of the biodegradable polymer and the salt was shaped into microneedles by moulding. Furthermore, the polymer penetrated the paper matrix owing to heating during the pressing process. Subsequently, the salt particles are removed to develop the porous structure. Various ratios of salt to polymer were investigated to adjust the porosity of microneedles as well as their sample absorption property. A paper‐based glucose sensor was integrated into the platform to demonstrate the absorption property of the microneedles, and showed successful sample extraction and glucose concentration analysis from agarose gel‐based skin mimic. The developed platform has the potential to integrate various paper‐based bio‐sensors to painless, disposal and fast screening and diagnostic test for patient, as well as those with prediabetes.

Recent advances in porous microneedles: materials, fabrication, and transdermal applications

“…Phase separation [81] Drug delivery / ISF sampling -Controllable pore size and mechanical strength -Difficulty in filling the MN mould due to the viscous polymer solution -Toxic and harmful organic porogen [81] Poly (lactic-co-glycolic acid) (PLGA) Emulsion and coating [32] Hot embossing [38] Porogen leaching [58] Drug delivery [32,38] ISF sampling [58] -Biocompatible and biodegradable material -Tuneable porosity by modulating porogen amount [32,58] -Limitation of the drug dosage [38] -Long time to remove the porogen [58] [58] to 60% have been reported. Moreover, the fracture force of a single needle, measured to be 3.1 ± 0.32 N, was sufficient for penetration into the skin of a rat [66].…”

“…drug-encapsulated nano-and micro-particle delivery) because of its biocompatibility and biodegradability [87][88][89]. Several approaches, such as emulsion followed by coating, hot embossing, and porogen leaching were developed to fabricate PLGA porous structures [32,38,58]. Using these methods, porosity is controllable and adjustable, resulting in pore diameters ranging from 1.9 to 15 µm; moreover, a porosity of 20.1 to 63% can be achieved.…”

“…One of its advantages in the aspect of Fig. 5 Porogen leaching process to produce continuous pores in MNs: a monomer and crosslinkers mixed with poly (ethylene glycol) porogens leached by methanol/water after irradiation with ultraviolet light (reproduced with permission [29]); b polydimethylsiloxane (PDMS) blended with salt eliminated by deionised (DI) water after curing (reproduced with permission [34]); c poly (lactic-co-glycolic acid) (PLGA)-mixed salt removed by DI water after PLGA solidification (reproduced with permission [58]) fabrication is that the pore size and porosity are both controllable based on the type and amount of used porogen.…”

“…Similar to PDMS, biodegradable porous PLGA MNs can also be produced using the salt-leaching method [58]. As depicted in Fig.…”

“…Porous MNs have interconnected micron-sized pores through which fluids can be transported because of the channel-like connected pores by capillary action, thereby transporting the collected fluid to the analysis system directly. Moreover, a wide range of biocompatible materials have been used for the fabrication of porous structures to extract skin ISF in a passive manner, enabling the collection of body fluids by detecting and analysing biomarkers using biosensors [34,58]. Although porous MNs have been researched for their various applications as well as unique characteristics, a detailed review on porous MNs has not been performed yet, as determined through our investigations so far.…”