3D-printed microneedles in biomedical applications

Abstract

Conventional needle technologies can be advanced with emerging nano-and micro-fabrication methods to fabricate microneedles. Nano-/micro-fabricated microneedles seek to mitigate penetration pain and tissue damage, as well as providing accurately controlled robust channels for administrating bioagents and collecting body fluids. Here, design and 3D printing strategies of microneedles are discussed with emerging applications in biomedical devices and healthcare technologies. 3D printing offers customization, cost-efficiency, a rapid turnaround time between design iterations, and enhanced accessibility. Increasing the printing resolution, the accuracy of the features, and the accessibility of low-cost raw printing materials have empowered 3D printing to be utilized for the fabrication of microneedle platforms. The development of 3D-printed microneedles has enabled the evolution of pain-free controlled release drug delivery systems, devices for extracting fluids from the cutaneous tissue, biosignal acquisition, and point-of-care diagnostic devices in personalized medicine.

Microneedle Arrays for Sampling and Sensing Skin Interstitial Fluid

“…3D printing is an emerging fabrication technology that has attracted significant attention, even for microfluidic applications [135]. Dabbagh et al thoroughly discussed the cutting edge advances in 3D printing technologies for MN fabrication, including stereolithography (SLA), digital light processing (DLP), continuous liquid interphase printing (CLIP), two-/multiphoton polymerisation (TPP/MPP), powder-bed-based methods, and direct energy deposition (DED) [136]. In the context of using hollow MNs for sensing applications, Wang's group recently fabricated acrylate-based polymer hollow MNs using the DLP 3D-printed technique and then treated this 3D-printed MN array with carbon and functionalised it with a catechol-agar (phosphate-buffer) solution for skin melanoma screening [133].…”

Finger-Actuated Microneedle Array for Sampling Body Fluids

“…An additional ability offered by MNs is the gradual release of substances for controlled drug delivery [72], promoting the potential applications of MNs for longer term treatments. Furthermore, microneedles can be integrated with biosignal acquisition techniques [7]. Therefore, MNs not only enable a minimally invasive injection experience, but they also can facilitate the development of wearable sensors [73] (with adherable MN patches) for continuous health monitoring, resulting in early diagnosis of disease, enhancing the success rate of therapies, decreasing healthcare costs, and ultimately promoting the wellbeing of the society.…”

“…Since their inception in 1976 as a drug delivery device [1] until 2020 where they were regarded as one of the top 10 emerging technologies [2], microneedles (MNs) have presented many advantages in injection processes, including minimizing insertion pain and reducing tissue damage and controlled drug delivery as compared to the conventional needle technologies. With different geometries and designs [3,4], such as solid, hollow, coated, or biodegradable [5] needle types in the scale of micrometers and nanometers [6], microneedle arrays (MNAs) can be fabricated with numerous methods such as 3D printing [7,8]. MNAs can be inserted into a target area, even within the depth of skin epidermis and thus they have emerging biomedical applications in drug delivery systems [9][10][11][12] with the capability of programmed deliveries of drug doses for multiple-injection therapies such as vaccination [13], sampling interstitial fluid (ISF) [14,15] biomarker detection [16], enhanced wound healing [17], fertility control [18], point-of-care (POC) setups and diagnostic tests [19,20], DNA extraction [21,22], cancer therapy [23], and force sensing [24].…”

Glioma-on-a-Chip Models

“…Since computer designs can be produced directly in this method, high expertise in micromanufacturing is not needed, enabling low-skill researchers to perform intricate design iterations/modifications with no need to third-party manufacturing companies [ 101 , 102 ]. Commonly used 3D printing techniques for microfluidic chip fabrication are extrusion-based methods (e.g., fused deposition molding (FDM, 50–200 μm resolution)), light-induced methods (e.g., stereolithography (SLA, 10 μm resolution), two-photon polymerization (MPP/TPP, 100 nm to 10 μm resolution), digital light processing (DLP, 25–100 μm resolution), polyjet methods (25 μm resolution), and powder-bed based methods with 50–250 μm resolution (selective laser sintering (SLS), and selective laser melting (SLM)) [ 103 , 104 , 105 ]. Table 2 summarizes the important features of 3D printing methods.…”