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RISS 인기검색어
- 검색키워드
- 저자 : Mark R. Prausnitz (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Analysis of the Mechanical Failure of Polymer Microneedles by Axial Force
박정환,Mark R. Prausnitz 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.4
A polymeric microneedle has been developed for drug delivery applications. The ultimate goal of the polymeric microneedle is insertion into the specified region without failure for effective transdermal drug delivery. The mechanical failure of various geometries of microneedles by axial load was modeled using the Euler formula and the Johnson formula to predict the failure force of taperedcolumn microneedles. These formulas were compared with measured data to identify the mechanical behavior of microneedles by determining the critical factors, including the actual length and the end-fixed factor. The comparison of the two formulas with the data showed good agreement at an end-fixity (K) of 0.7. This value means that a microneedle column has one fixed end and one pinned end and that part of the microneedle is overloaded by an axial load. When the aspect ratio of length-to-equivalent diameter is 12:1 at Young’s modulus of 3 GPa, there is a transition from the Euler region to the Johnson region due to the decreased length and the increased base diameter of the microneedle. A polymer having a stiffness of less than 3 GPa would follow the Euler formula. A 12:1 aspect ratio of length-to-equivalent diameter of the microneedle is a mechanical indicator determining the failure mode between elastic buckling and inelastic buckling at Young’s modulus of less than 3 GPa for polymer. Microneedles with an aspect ratio of length-to-equivalent diameter below 12:1 and Young’s modulus of more than 3 GPa are recommended for reducing sudden failure by buckling and for successfully inserting a microneedle into the skin.
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Polymeric Tube-Shaped Devices with Controlled Geometry for Programmed Drug Delivery
박민,최영빈,박천권,이승호,이지은,조은빛,Mark R. Prausnitz 한국고분자학회 2012 Macromolecular Research Vol.20 No.9
We developed a modular tube-shaped device as a proof of principle to enable the programmed release of encapsulated molecules for controlled drug delivery. Each drug-delivery tube module was prepared by assembling two separate silicone tubes in a series, one filled with a model compound (sodium fluorescein) and the other with a diffusional barrier material (polyethylene oxide, PEO). We varied the length of the PEO-filled tubes to control the release from the drug-delivery tube devices. The onset times and periods of drug release increased with the length of the PEO tube. To program the drug release, therefore, we prepared devices with combinations of drug-delivery tube modules with different lengths of PEO-filled tubes. Using PEO-filled tubes with very different lengths achieved a pulsatile drug release while a continuous drug release was realized by using PEO-filled tubes with small differences in length. We concluded that the modular combination of drug-delivery tubes, each composed of a diffusionbarrier tube of different length, demonstrates good potential for applications in programmed drug delivery.
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