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Dehbari N, Tavakoli J, Zhao J, Tang Y. Enhancing water swelling ability and mechanical properties of water-swellable rubber by PAA/SBS nanofiber mats. J Appl Polym Sci 2016. [DOI: 10.1002/app.44213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nazila Dehbari
- Centre for NanoScale Science & Technology and School of Computer Science, Engineering and Mathematics; Flinders University; Bedford Park SA 5042 Australia
| | - Javad Tavakoli
- Medical Device Research Institute (MDRI) and School of Computer Science, Engineering & Mathematics; Flinders University; Bedford Park SA 5042 Australia
| | - Jinchao Zhao
- School of Chemistry and Chemical Engineering, Hubei Biomass Fibres and Eco-Dyeing & Finishing Key Laboratory; Wuhan Textile University; Wuhan 430064 People's Republic of China
| | - Youhong Tang
- Centre for NanoScale Science & Technology and School of Computer Science, Engineering and Mathematics; Flinders University; Bedford Park SA 5042 Australia
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Affiliation(s)
- Jennifer C. Case
- Department of Mechanical Engineering, Purdue University, West Lafayette, Indiana
| | - Edward L. White
- Department of Mechanical Engineering, Purdue University, West Lafayette, Indiana
| | - Rebecca K. Kramer
- Department of Mechanical Engineering, Purdue University, West Lafayette, Indiana
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Microsphere-assisted fabrication of high aspect-ratio elastomeric micropillars and waveguides. Nat Commun 2015; 5:3324. [PMID: 24525627 DOI: 10.1038/ncomms4324] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/27/2014] [Indexed: 11/08/2022] Open
Abstract
High aspect-ratio micropillars are in strong demand for microtechnology, but their realization remains a difficult challenge, especially when attempted with soft materials. Here we present a direct drawing-based technique for fabricating micropillars with poly(dimethylsiloxane). Despite the material's extreme softness, our technique enables routine realization of micropillars exceeding 2,000 μm in height and 100 in aspect-ratio. It also supports in situ integration of microspheres at the tips of the micropillars. As a validation of the new structure's utility, we configure it into airflow sensors, in which the micropillars and microspheres function as flexible upright waveguides and self-aligned reflectors, respectively. High-level bending of the micropillar under an airflow and its optical read-out enables mm s(-1) scale-sensing resolution. This new scheme, which uniquely integrates high aspect-ratio elastomeric micropillars and microspheres self-aligned to them, could widen the scope of soft material-based microdevice technology.
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Lee CD, Hara SA, Yu L, Kuo JTW, Kim BJ, Hoang T, Pikov V, Meng E. Matrigel coatings for Parylene sheath neural probes. J Biomed Mater Res B Appl Biomater 2015; 104:357-68. [PMID: 25809504 DOI: 10.1002/jbm.b.33390] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/26/2014] [Accepted: 01/29/2015] [Indexed: 01/15/2023]
Abstract
The biologically derived hydrogel Matrigel (MG) was used to coat a Parylene-based sheath intracortical electrode to act as a mechanical and biological buffer as well as a matrix for delivering bioactive molecules to modulate the cellular response and improve recording quality. MG was loaded with dexamethasone to reduce the immune response together with nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) to maintain neuronal density and encourage neuronal ingrowth toward electrodes within the sheath. Coating the Parylene sheath electrode with the loaded MG significantly improved the signal-to-noise ratio for neural events recorded from the motor cortex in rat for more than 3 months. Electron microscopy showed even coverage of both the Parylene substrate and the platinum recording electrodes. Electrochemical impedance spectroscopy (EIS) of coated electrodes in 1× phosphate-buffered saline demonstrated low impedance required for recording neural signals. This result was confirmed by in vivo EIS data, showing significantly decreased impedance during the first week of recording. Dexamethasone, NGF, and BDNF loaded into MG were released within 1 day in 1× phosphate-buffered saline. Although previous studies showed that MG loaded with either the immunosuppressant or the neurotrophic factor cocktail provided modest improvement in recording quality in a 1-month in vivo study, the combination of these bioactive molecules did not improve the signal quality over coating probes with only MG in a 3-month in vivo study. The MG coating may further improve recording quality by optimizing the in vivo release profile for the bioactive molecules.
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Affiliation(s)
- Curtis D Lee
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Seth A Hara
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Lawrence Yu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Jonathan T W Kuo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Brian J Kim
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Tuan Hoang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111
| | - Victor Pikov
- Neural Engineering Program, Huntington Medical Research Institutes, Pasadena, California, 91105-3104
| | - Ellis Meng
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089-1111.,Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California, 90089-2560
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Peters C, Ergeneman O, Sotiriou GA, Choi H, Nelson BJ, Hierold C. Visible light curing of Epon SU-8 based superparamagnetic polymer composites with random and ordered particle configurations. ACS APPLIED MATERIALS & INTERFACES 2015; 7:193-200. [PMID: 25479462 DOI: 10.1021/am5056728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The performance of superparamagnetic polymer composite microdevices is highly dependent on the magnetic particle content. While high loading levels are desired for many applications, the UV absorption of these nanoparticles limits the overall thickness of the fabricated microstructures and subsequently their capability of magnetic interaction. The combination of a visible-light-sensitive photoinitiator and particle self-organization is proposed to extend the exposure depth limitation in Epon SU-8 based superparamagnetic polymer composites. While superparamagnetic iron oxide particles strongly absorb i-line radiation required to cross-link the Epon SU-8 polymer matrix, we propose the utilization of H-Nu 470 photoinitiator to expand the photosensitivity of the composite toward the visible spectrum, where the dispersed nanoparticles are more transparent. The novel photoinitiator preserves the composite's superparamagnetic properties as well as a homogeneous particle distribution. As a result, particle load or resist thickness can be more than doubled while maintaining exposure time. The self-organization of ordered magnetic structures allows for an additional increase in exposure depth of up to 40%, resulting in a 2.5-fold saturation magnetization.
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Affiliation(s)
- Christian Peters
- Micro and Nanosystems, Department of Mechanical and Process Engineering, ETH Zurich , Tannenstrasse 3, 8092 Zurich, Switzerland
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