• Polymer(Korea)
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• v.38 no.3
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• pp.391-396
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• 2014

Polymer microneedles can be fabricated by a micromolding method, an easy and cost-effective method. However, it is not easy to achieve uniform coating with an aqueous coating solution due to hydrophobic surface of polymer microneedles. 3-Dimensional coating polymer microneedles could deliver more than twice as much dose as in-plane metal microneedles by increasing coating area and the number of microneedles per unit area. A uniform coating was not obtained by addition of coating additives in the coating solution. The satisfied coating was achieved by treatment of surface of polymer microneedle with metal deposition and UV/ozone, and UV/ozone treatment was an ultimate surface treatment method based on biological safety. Calcein coating polymer microneedles were prepared by using UV/ozone treatment and followed dip-coating, and they delivered calcein in porcine skin successfully after 15 min of insertion.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.429-434
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• 2021

The feasibility of lecithin as a material for dissolving microneedles to improve skin permeability of drugs and the effect of the composition of lecithin on the mechanical strength, solubility, and skin permeability of rhodamine B (RhB) of the dissolving microneedles were investigated. Dissolving microneedles with needles of uniform shape and size were fabricated with the mold made using the laser-writing technique, simpler and more efficient method compared to the photolithography method, the conventional method to fabricate the microneedle mold. The composition of lecithin in the microneedle affected the mechanical strength and solubility of the needle thus, the mechanical strength of the needle increased as the composition of lecithin in the needle increased, resulting in improving the skin permeability of RhB contained in the microneedles. When comparing the microneedles containing same composition of amylopectin (AP), the skin permeability of RhB of the microneedles containing lecithin was higher. These results indicate that lecithin can be used as a material for dissolving microneedles and the skin permeability of the microneedle could be controlled by changing the composition of lecithin.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1721-1725
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• 2010

This paper reports the fabrication of geometry-controlled carbon microneedles by a backside exposure method and pyrolysis. The SU-8 microneedles are a polymer precursor in a carbonization process, which geometries such as base diameter, spacing, and aspect ratio can be controlled in a photolithography step. Using this fabrication method, highly reproducible carbon microneedles, which have high aspect ratios of more than 10 and very sharp nanotips, can be realized. The quartz surface with carbon microneedles becomes very hydrophilic and its wettability is adjusted by carrying out the silane treatment. In the carbon microneedle array ($3\;{\mu}m{\times}3\;{\mu}m$), the contact angle is extremly enhanced (${\sim}180^{\circ}$); this will be advantageous in developing low-drag microfluidics and labs-on-a-chip as well as in other bio-applications.

• Polymer(Korea)
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• v.37 no.3
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• pp.393-398
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• 2013

Two types of polymeric micro-needles with 250 and $750{\mu}m$ lengths were prepared by a micromolding process. The geometry of dissolving micro-needles with minoxidil was investigated and the mechanical property of polymer micro-needles was also evaluated. Water dissolving micro-needles containing minoxidil were successfully inserted into skin and delivered minoxidil to the skin layer after 30 min of insertion. The observed hair growth was less when the minoxidil treatment was not applied or used without the micro-needles than that the minoxidil was applied by micro-needles. Histologically, these hair follicles became bigger, and the hair papillae were totally encircled by the hair bulbs. In this feasibility test, we show the successful delivery of minoxidil, and effective treatment of hair loss can be possible by using dissolving micro-needles with minoxidil.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.4
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• pp.241-251
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• 2010

In recent years, the number of people suffering from depression due to hair loss has been increasing. The treatment methods such as clinical pathology and vanity surgery have been developed. There are therapies and materials for hair growth promotion and hair loss prevention. But the effectiveness of such therapies and materials is not fully evaluated and some side-effects have been reported. In this study, microneedle therapy using very thin and delicate needles promotes absorption of drug. During this therapy, the microneedle makes micro holes that help absorbion of drugs into the scalp. In this study, absorbion of fermented soybean were evaluated. The ingredient has antioxidant, antiandrogen, and antithrombosis effect for alopecia. The fermented soybean is more effective for complex hair loss when used with microneedle. It is because of the microneedle's excellent drug delivery system (DDS). This therapy that increases the absorption of fermented soybean is a very useful scalp care method which prevents, treats and controls alopecia. This microneedle therapy using fermented soybean is an advanced technology for scalp care.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.650-655
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• 2016

In this study, a computational simulation of the internal flow characteristics was carried out for a Urea-SCR Injector. A single hole swirl injector with a swirl disk and slanted nozzle was used in this simulation. The maximum needle lift and opening velocity were selected as the design parameters. To analyze the unsteady internal flow characteristics of the Urea-SCR injector, the moving grid technique was applied to simulate the delicate needle movement. According to the simulation results, the injected mass flow rate from the Urea-SCR injector decreased with increasing needle opening velocity and maximum needle lift. This is because the Urea-solution tends to fill the empty space that the needle previously occupied. The swirl flow is decreased as the flow goes through the injector nozzle, because of the friction with the nozzle wall. Also, during the maximum needle lift period, the swirl coefficient and mean swirl coefficient increase with increasing needle lift. The results of this study may be used as the basic design data of related injectors.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.379-384
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• 2021

A microneedle is a tool that used for drug delivery and diagnosis. Unlike general injections, the microneedle is short in length, enabling effective drug delivery while minimizing pain and risk of infection. Conventionally, microneedles have been manufactured precisely at a nanometer level based on microelectro mechanical systems (MEMS) technology, requiring expensive equipments & maintenance and complicated processes. To address the issues, 3D printing research has been conducted to fabricate microneedles simply, economically, and rapidly. Since 3D printing facilitates to manufacture prototypes and apply feedbacks, it is advantageous for the development and commercialization of microneedle for pharmaceuticals and cosmetics. Therefore, this review will introduce stereolithography (SLA), two-photon polymerization (2PP), dynamic light processing (DLP), continuous liquid interface production (CLIP), and fused deposition modeling (FDM) 3D printing technologies and also highlight research trends for microneedle production using them. Furthermore, the limitation of the current microneedle technology and the direction to be solved in the future will be discussed.

• Applied Chemistry for Engineering
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• v.35 no.5
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• pp.423-428
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• 2024

Microneedles with micron-sized needle arrays are an emerging technology for the transdermal administration of active pharmaceutical ingredients with minimally invasive pain. Over the past decade, although various additive manufacturing technologies have been employed for precise fabrication of microneedles, these methods are often limited by material compatibility and bioavailability, in addition to being time-consuming and costly. In here, we compare the resolution of Polyjet and DLP-SLA 3D printing methods for the precise fabrication of biodegradable PCLDA/PEGDA microneedles. To enhance the structural accuracy of the microneedles from both printing methods, we evaluate the 3D printing conditions, including 3D printing angle and needle height and diameter. Molds for microneedles are fabricated using optimized 3D printing methods, and subsequent replica molding processes are employed to fabricate the polymeric microneedles with sharp need tips. Finally, we use photocurable PCLDA and PEGDA for biodegradable and biocompatible microneedles, and their mechanical properties as PCLDA concentrations are analyzed to assess the strength required for skin insertion. This study has demonstrated the efficient and low-cost fabrication of high-resolution microneedles for transdermal drug delivery.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.249-252
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• 1998

니들펀칭 부직포는 구성 섬유소 집합체(web)를 바늘에 펀칭시켜 통과시킴으로써 섬유소간의 물리적인 결합력을 이용하여 제작한 섬유 구조물을 말한다. 니들펀칭 부직포의 물성에 미치는 인자는 크게 다음 세가지라고 볼 수 있다. 첫째, web을 구성하는 섬유의 물성이다.[1-4] 즉, 구성섬유의 인장성질이나 단면의 모양, 크림프의 존재유무, 섬도, 섬유길이, 마찰특성들이 부직포의 물성에 직접적인 영향을 준다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.467-470
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• 2008

추진기관용 노즐에 사용하는 대표적인 소재로는 흑연소재와 탄소/탄소 복합재료를 들 수 있다. 흑연 소재는 열충격 저항성이 취약하여 사용 중 파손의 발생가능성이 높아 현재는 열축격 저항성이 우수한 탄소/탄소 복합재료를 주로 사용하고 있다. 본 연구를 통하여 수입에 의존하였던 Quasi-3D 구조의 니들펀치(Needle Punch) 프리폼을 국산화 개발하였다. 본 연구에서는 니들펀치 프리폼의 제조 공정 및 밀도화 공정을 다루고자 한다.