Browsing by Author "Kafadenk, Abdullah"

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A high-precision method for manufacturing tunable solid microneedles using dicing saw and xenon difluoride-induced dry etching
(Elsevier BV, 2023-12-19) Eş, İsmail; Kafadenk, Abdullah; İnci, Fatih
Numerous fabrication techniques have been employed to produce solid microneedles (MNs); yet precise manufacturing of MNs with adjustable features (height, aspect ratio, and array number) remains the main limitation. Developing tunable MNs holds immense promise for personalized and efficient drug delivery systems. In this study, we utilized a combination of dicing saw and XeF2 isotropic dry etching processes to fabricate solid MNs with tunable characteristics. We herein created rectangular arrays using a dicing saw with desired geometry followed by dry etching to form MN arrays without further processing. Employing optimized parameters, the average heights of the MNs were 522 +/- 15 mu m, 614 +/- 42 mu m, and 698 +/- 22 mu m for initial pattern depths of 500 mu m, 600 mu m, and 700 mu m, respectively. Moreover, we achieved an aspect ratio as high as 3.7, a radius of curvature less than 10 mu m, and a tip angle as low as 6.4(o). The mechanical and surface properties of the MNs were enhanced through magnetron sputtering with titanium. An ex vivo penetration test conducted on porcine skin demonstrated the significant potential of these MNs for transdermal drug delivery in future investigations. Overall, a cost-effective production of a single solid MN patch, featuring 400 MN arrays per cm(2), can be achieved within a remarkably short timeframe (approximately 2 h). Investigating fundamental principles, this study addresses the persistent challenge in manufacturing solid MNs with adjustable features, such as height, aspect ratio, and array number. This presents a substantial advantage over alternative fabrication techniques.
Open Access
Manufacturing of microfluidic sensors utilizing 3d printing technologies: A production system
(Hindawi Limited, 2021-08-11) Khorsandi, D.; Nodehi, M.; Waqar, T.; Shabani, M.; Kamare, B.; Zare, E. N.; Ersoy, S.; Annabestani, M.; Çelebi, M. F.; Kafadenk, Abdullah
3D integrated microfluid devices are a group of engineered microelectromechanical systems (MEMS) whereby the feature size and operating range of the components are on a microscale. These devices or systems have the ability to detect, control, activate, and create macroscale effects. On this basis, microfluidic chips are systems that enable microliters and smaller volumes of fluids to be controlled and moved within microscale-sized (one-millionth of a meter) channels. While this small scale can be compared to microfluid chips of larger applications, such as pipes or plumbing practices, their small size is commonly useful in controlling and monitoring the flow of fluid. Through such applications, microfluidic chip technology has become a popular tool for analysis in biochemistry and bioengineering with their most recent uses for artificial organ production. For this purpose, microfluidic chips can be instantly controlled by the human body, such as pulse, blood flow, blood pressure, and transmitting data such as location and the programmed agents. Despite its vast uses, the production of microfluidic chips has been mostly dependent upon conventional practices that are costly and often time consuming. More recently, however, 3D printing technology has been incorporated in rapidly prototyping microfluid chips at microscale for major uses. This state-of-the-art review highlights the recent advancements in the field of 3D printing technology for the rapid fabrication, and therefore mass production, of the microfluid chips.
Open Access
Xenon difluoride dry etching for the microfabrication of solid microneedles as a potential strategy in transdermal drug delivery
(Wiley-VCH Verlag GmbH & Co. KGaA, 2023-07-23) Eş, İsmail; Kafadenk, Abdullah; Görmüş, M. Burak; İnci, Fatih
Although hypodermic needles are a “gold standard” for transdermal drug delivery (TDD), microneedle (MN)-mediated TDD denotes an unconventional approach in which drug compounds are delivered via micron-size needles. Herein, an isotropic XeF2 dry etching process is explored to fabricate silicon-based solid MNs. A photolithographic process, including mask writing, UV exposure, and dry etching with XeF2 is employed, and the MN fabrication is successfully customized by modifying the CAD designs, photolithographic process, and etching conditions. This study enables fabrication of a very dense MNs (up to 1452 MNs cm−2) with height varying between 80 and 300 µm. Geometrical features are also assessed using scanning electron microscopy (SEM) and 3D laser scanning microscope. Roughness of the MNs are improved from 0.71 to 0.35 µm after titanium and chromium coating. Mechanical failure test is conducted using dynamic mechanical analyzer to determine displacement and stress/strain values. The coated MNs are subjected to less displacement (≈15 µm) upon the applied force. COMSOL Multiphysics analysis indicates that MNs are safe to use in real-life applications with no fracture. This technique also enables the production of MNs with distinct shape and dimensions. The optimized process provides a wide range of solid MN types to be utilized for epidermis targeting.