Photonic crystals in biology - NanoTR-VI

PPPPoster Session, Thursday, June 17Theme F686 - N11233-D Fluorescence and Colored Patterns of Polydiacetylene Supramolecules1232Oktay Yarimaga,P PSumi Lee,P PYang-Kyu ChoiP P* and UJong-Man KimUP P*1PInstitute of Nanoscience and Technology, Hanyang University, Seoul, 133-791, Korea2PDepartment of Chemical Engineering, Hanyang University, Seoul, 133-791, Korea3PDepartment of Electrical Engineering, KAIST, 305-701, KoreaAbstract-We present the results of investigation on a polydiacetylene (PDA)-based thermal imaging system, both as a thermo-fluorescencesensor and a thermochromic display. By using raplica-molding of PDA supramolecules embedded to polyvinyl alcohol and a consequentback-side irradiation, it is posssible to obtain 3-dimentional colored image and morphological patterns on free-standing elastic film. Thesimilar method is also useful to fabricate a pixel of the thermochromic display. Morphological and optical properties of the generated patternsare very promising for micro-thermal imaging applications.Polydiacetylenes (PDAs) are unique materials in terms oftheir stress induced chromatic transitions [1]. They are one ofthe thermo-fluorescent materials, i.e. thermal stress inducesnon-fluorescent to fluorescent phase switching. And moreinterestingly, the fluorescence intensity strongly depends onthe temperature of the vesicles [2]. Up to date, most of theinvestigations on PDAs have focused on the generation andpatterning of different PDA derivatives in forms of selfassembledlayers, supramolecular structures and microclusters[3], [4]. Generation of colored images on batch typefilms by UV-light irradiation through a photo-mask is anotherelegant example of patterning techniques [5]. Although thereported investigations contributed to the ongoing course ofPDA-based chemo/thermo/bio imaging system development,we have realized that utilization of the pre-patterned structuresin the desired applications have been limited due to substrateselectiveness and challenges arising from the fabricationprocess. Accordingly, we have recently reported a novelmethod to fabricate 3-dimensional (3-D) colored andfluorescence images on a free-standing composite film [6].by mixing and stirring steps, replica molding process was usedto transfer the size and shape of the mold bearings to the PDA-PVA composite solid film. A UV-light irradiation from theback-side of the mold afforded polymerization of diacetylenevesicles to PDA with a color transition to blue, selectively onthe replicated features (Figure 1).Due to size reduction factor, the dimensions of the desiredpatterns should be designed carefully. “The smaller the moldpattern, the larger the size reduction factor” is the key conceptto consider. Replicated and polymerized blue color structurespossess very attractive properties in terms of elasticity,thermo-chromism, thermo-fluorescence and 3-D morphologywhich form the bases of a thermal imaging system.A similar approach has been effectively employed also todemonstrate thermochromic information display [7]. This timemicro-pixel array of PDA-embedded PVA composite wasformed on micro-heaters using replica-molding and blue-toredcolor transition of the pixels was achieved by supplyingthermal stress from the built-in micro-heaters.We will discuss the possible effects of dimensionalshrinking on heating and cooling cycle (response time) of thedisplay system and the advantages of having 3-D pixels interms of visible color contrast and fluorescence intensity.The authors gratefully thank to National ResearchFoundation of Korea for financial support throughInternational Research & Development Program(K20901000006-09E0100-00610). This work was supportedby the ERC program grant (No. R11-2007-045-03004-0) and agrant from the National Research Laboratory (NRL) program(No. R0A-2007-000-20028-0 and 20090083161) of theKorean Science and Engineering Foundation (KOSEF), whichis funded by the Korean Ministry of Education, Science andTechnology (MEST). We would like to thank to CAFDCcenter for their support.Figure 1. (a) PDA-embedded PVA film during peeling off froma mold after replica molding process and polymerization. (b)The blue film shifts color to red with thermal stress. (c) PDA isnot fluorescent in blue phase while in red phase it fluoresces. (d)3-D morphological structure of image patterns is very attractivefor construction of elastic fluidic micro-chips.In our knowledge, the methods dealing with micro-thermalanalysis are quite complicated and expensive. Present studywill focus on the generation and integration of PDA-basedthermochromic morphological and image patterns in order toimplement a thermal monitoring system, both as a sensor anda display. After embedding the monomer diacetylene vesiclesinto a host polymer matrix such as polyvinyl alcohol (PVA)*Corresponding author: HTjmk@hanyang.ac.krTH[1] D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science261, 585 (1993).[2] R. W. Carpick, T. M. Mayer, D. Y. Sasaki, A. R. Burns,Langmuir 16, 4639 (2000).[3] J. H. Baek, H. Ahn, J. Yoon, J.-M. Kim, Macromol. RapidCommun. 29, 117 (2008).[4] T. Kim, R. M. Crooks, M. Tsen, L. Sun, J. Am. Chem. Soc. 117,3963, (1995).[5] J.-M. Kim, Y. B. Lee, S. K. Chae, D. J. Ahn, Adv. Funct. Mater.16, 2103 (2006).[6] O. Yarimaga, S. Lee, J.-M. Kim, Y.-K. Choi, Macromol. RapidComm. 31, 270 (2010).[7] O. Yarimaga, M. Im, B. Gu, T. W. Kim, Y. K. Jung, H. G. Park,Y-K. Choi, Proceedings of MEMS2008, 750-753 (2008).6th Nanoscience and Nanotechnology Conference, zmir, 2010 685