Publications

@conference{Hoang2025,

title = {Free-templated Microfabrication of Hydrogel Microneedles Using Electrohydrodynamic Technique for Transdermal Drug Delivery},

author = {T. A. Hoang, H. D. Vu, D. Ngo, N. L. Mai, C. Doan, D. K. Tran, Y. Xiao, B. Rehm, Y. K. Yong, V. T. Dau},

year  = {2025},

date = {2025-11-03},

urldate = {2025-11-03},

booktitle = {The 29th International Conference on Miniaturized Systems for Chemistry and Life Sciences -

Micro-Total Analysis Systems (uTas)},

address = {Adelaide, 2 - 6 November, 2025},

abstract = {This study presents a template-free electrostreching microfabrication method for hydrogel microneedles, targeting applications in wound healing and drug delivery. Precursor solutions of gelatin methacryloyl (GelMa) and hyaluronic acid methacryloyl (HAMA) were subjected to a high-voltage electric field, forming a hydrogel microneedle structure by undergoing UV-crosslinking and solvent evaporation. The fabricated microneedles demonstrated optimal geometries, i.e., height-to-base ratios and the ability to be grown in parallel. In vitro cytotoxicity test confirmed the biocompatibility of the microneedles, as cells were able to adhere and proliferate on their surfaces.



Traditional transdermal drug delivery approaches, including hypodermic needles, topical creams, and transdermal patches, have significant drawbacks such as slow drug absorption and the painful and discomfort injection process [1], [2], [3]. Microneedles, which are arrays of micron-scale needles arranged in a small patch, offer an effective alternative solution by combining a non-invasive method and fast onset action to enhance patient compliance and potential for self-administration. Although there are various types of microneedles, most are fabricated using template-based methods such as moulding, lithography, or top-down micromachining, which require complicated processes in cleanroom facilities and limit design flexibility. To address these limitations, we report a template-free fabrication approach using electrohydrodynamic principles to produce microneedles directly on multiple substrate materials. Building upon prior work introduced in Small Methods [4], which focused on a proof-of-concept demonstration, this study extends the application to biocompatible hydrogels and evaluates the system’s scalability and safety for transdermal drug delivery. The method enables parallel microneedle fabrication and supports cell viability, highlighting its potential for practical therapeutic applications.



An overview of microneedle fabrication is illustrated in Figure 1. A hydrogel solution containing GelMa, HAMA, and the photo-initiator LAP (Lithium phenyl-2,4,6-trimethylbenzoylphosphinate) was prepared and dispensed as a droplet onto a substrate positioned between the two high-voltage electrodes. Under the applied pulsating electric field  , the droplet was elongated and stretched into a conical shape (Taylor-cone shape). The droplet was then exposed to UV light to initiate hydrogel photo-polymerisation, which solidified the droplet’s outer layer. By the subsequent air-dry process, the solvent completely evaporates, resulting in a solid microneedle. This method enabled parallel microneedle formation, as shown in Figure 2, where five microneedles were simultaneously grown with consistent form and geometry. Figure 3 demonstrates the in-situ adaptability of the method, showcasing its ability to grow microneedles directly on various commercially available adhesive patches. GHMa-1, -2, and -3 samples exhibited desirable geometries, with height-to-base ratios from 1.90 to 3.23 (Table 1). Biocompatibility of the microneedle was validated by culturing cells (RAW 264.7) in direct contact with the microneedle, where cell adhesion and proliferation were observed (Figure 4). These findings underscore the potential of this technique for scalable and flexible fabrication of biocompatible hydrogel transdermal drug delivery platforms.},

keywords = {Electrohydrodynamics, Microneedles, Pulsed voltage},

pubstate = {published},

tppubtype = {conference}

}