Recent advances in nanotechnology have enabled materials and devices to be fabricated at the nanoscale. One of the motivations for the miniaturization process of materials is the superior mechanical properties that nanostructured materials possess as compared to bulk materials. Nanostructured materials such as nanofibers, nanotubes and nanowires have been used for a wide range of applications including tissue engineering, filter media, reinforcement in composites and Micro/Nano-Electro-Mechanical Systems (MEMS/NEMS). Such nanostructures can be made from various materials such as polymers, carbon and semiconductors into the form of continuous nanofibers, nanofibrous networks or short nanowires and nanotubes. During the service lifetime of these nanostructures, forces exerted on them in the form of mechanical contact or thermal misfit may result in permanent deformation or even failure. For example, the mechanical properties of the nanofibers that make up the nanofibrous tissue engineering scaffold can affect cell morphology, proliferation and differentiation. Structural integrity is required for the scaffold before new tissue can be formed. Therefore, there is a need to characterize the mechanical properties of these nanostructures. Commercial mechanical testing systems have been used to test fibers as small as about 10 um in diameter. However, as the size of the fibers is further reduced, such mechanical testing systems are not suitable for testing these nanostructures. Here, we develop a suite of nanomechanical testing methodologies to conduct mechanical tests on a single nanofiber – these include the nano tensile test, nano 3-point bend test and nanoindentation. Our developed nanomechanical testing methodologies will not only allow the probing of the nanomechanical properties of nanostructures, but also allow designers of micro and nanodevices determine the structural integrity and reliability of the miniaturized components in their products. This research is done in collaboration with Asst Prof Sow Chorng Haur (Dept of Physics, NUS) and Asst Prof Vincent Tan (Dept of Mechanical Engineering, NUS).
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References
- Tan, E P S, S Y Ng, C T Lim, Effects of Crystalline Morphology on the Tensile Properties of Electrospun Polymer Nanofibers, Applied Physics Letters, 2008. (in press)
- Zhang, Y Z, B Su, C T Lim, S Ramakrishna, Chitosan nanofibres from an easily electrospinnable UHMWPEO doped chitosan solution system, Biomacromolecules, 9, 1 (2008): 136-141.
- Unnikrishnan, V U, G U Unnikrishnan, J N Reddy, C T Lim. Atomistic-mesoscale coupled mechanical analysis of polymeric nanofibers. Journal of Materials Science, 42, 21 (2007): 8844-8852.
- Chong, E J, T T Phan, I J Lim, Y Z Zhang, B H Bay, S Ramakrishna, C T Lim. Evaluation of electrospun PCL/Gelatin nanofibrous scaffold for wound healing and layered dermal reconstitution. Acta Biomaterialia, 3 (2007): 321–330.
- Tan, E P S, Y Zhu, T Yu, L Dai, C H Sow, V B C Tan, C T Lim. Crystallinity and surface effects on the Young’s modulus of CuO nanowires. Applied Physics Letters, 90, 16 (2007):163112-163115. (also in Virtual Journal of Nanoscale Science & Technology, AIP, 15, 17, 2007).
- Tan, E P S and C T Lim, Nanomechanical characterization of nanofibers – A review. Composite Science & Technology, 66, 9 (2006): 1099-1108
- Chew, S Y, T C Hufnagel, C T Lim and K W Leong, Mechanical Properties of Single Electrospun Drug-Encapsulated Nanofibres. Nanotechnology, 17 (2006):3880-3891.
- Tan, E P S and C T Lim, Characterization of bulk properties of polymer nanofibrous scaffolds from nanomechanical properties of single nanofibers. Journal of Biomedical Materials Research – Part A, 77A, 3 (2006): 526-533.
- Tan, E P S and C T Lim. Effects of annealing on the structural and mechanical properties of electrospun polymeric nanofibres. Nanotechnology, 17 (2006): 2649-2654.
- Zhang, Y Z, J Venugopal, Z-M Huang, C T Lim, S Ramakrishna, Crosslinking of the electrospun gelatin nanofibers. Polymer, 47, 8 (2006): 2911-2917.
- Zhang, Y Z, X Wang, Y Feng, J Li, C T Lim, S Ramakrishna. Coaxial electrospinning of fitcBSA encapsulated PCL nanofibers for sustained release. Biomacromolecules, 7, 4 (2006): 1049-1057.
- Zhang, Y Z, Y Feng, Z M Huang, S Ramakrishna and C T Lim, Fabrication of Porous Electrospun Nanofibers, Nanotechnology, 17 (2006): 901-908.
- Zhang, Y Z, C T Lim, S Ramakrishna and Z M Huang, Recent development of polymer nanofibers for biomedical and biotechnological applications. Journal of Materials Science - Materials in Medicine, 16, 10 (2005): 933-946.
- Song, T, Y Z Zhang, T J Zhou, C T Lim, S Ramakrishna and B Liu, Encapsulation of self-assembled FePt magnetic nanoparticles in PCL nanofibers by coaxial electrospinning. Chemical Physics Letters, 415, 4-6 (2005): 317-322
- Tan, E P S and C T Lim. Physical properties of a single polymeric nanofiber. Applied Physics Letters, 84, 9, (2004): 1603-1605. (also in Virtual Journal of Nanoscale Science & Technology, AIP, 9, 9, 8 March 2004.)
- Tan, E P S, and C T Lim. A novel approach to tensile testing of micro- and nanoscale fibers. Review of Scientific Instruments, 75(8):2581-2585, 2004. (also in Virtual Journal of Nanoscale Science & Technology, AIP, 10, 10, 6 Sep 2004.)
- Zhang, Y Z, J R Venugopal, Z M Huang, C T Lim and S Ramakrishna, Characterization of the surface biocompatibility of the electrospun PCL-collagen nanofibers using fibroblasts. Biomacromolecules, vol 6, no 5 (2005): 2583-2589.
- Zhang, Y Z, H W Ouyang, C T Lim, S Ramakrishna and Z M Huang. Electrospinning of Gelatin fibers and Gelatin/PCL composite fibrous scaffolds. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 72B, 1 (2005): 156-165.
- Tan, E P S, S Y Ng and C T Lim. Nano tensile testing of a single ultrafine polymeric nanofiber. Biomaterials, 26, 13 (2005): 1453-1456.
- Tan, E P S, C N Goh, C H Sow and C T Lim, Tensile test of a single nanofiber using an atomic force microscope tip. Applied Physics Letters, 86 (2005): 073115-073117. (also in Virtual Journal of Nanoscale Science & Technology, AIP, 11, 7, 21 Feb 2005 and Virtual Journal of Biological Physics Research, AIP & APS, 9, 4, 15 Feb 2005.)
- Tan, E P S, C T Lim, Nanoindentation study of nanofibers. Applied Physics Letters, 87 (2005):123106-123109.
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