Magnetic Resonance Signal-Enhancing Self-Assembled Coating for Endovascular Devices
✍ Scribed by B. Thierry; S. Faghihi; L. Torab; G. B. Pike; M. Tabrizian
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 379 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0935-9648
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✦ Synopsis
tor was submerged in a thermostated water bath and stirred at 250 rpm. After 20 min, the homogeneous mixture of methyl methacrylate, vinylcarbazole, the oxadiazole derivative (NDA), and the perylene was poured into the reactor and stirred vigorously. The mixture was allowed to polymerize at 70 C for 7 h. Sodium bicarbonate and sodium persulfate were dissolved in water and added to the reaction mixture. The product was filtered and washed with DDI water. A standard recipe for emulsion copolymerization is shown in Table 1.
Fabrication and Characterization of EL Devices:
The indium tin oxide (ITO)-coated glass substrates (10 X cm ±2 ) were first patterned, and then cleaned according to the RCA procedure [24] (utilizing H 2 O/H 2 O 2 /NH 3 , 10:2:0.6, 55±60 C, 75 min). A thin polymer film was formed on the patterned ITO glass plate by spin-coating 10 wt.-% of an ELC colloidal dispersion in a 1 wt.-% poly(vinyl alcohol) (PVA)/ DDI water solution followed by drying under a vacuum for 6 h. The aluminum cathode was deposited on top of the polymer layer by thermal evaporation in a bell jar under a vacuum (<10 ±6 torr). The LED was thus a sandwich of ITO/ELC/Al with an active area of approximately 0.785 mm 2 . The LED was characterized by its current±voltage (I±V) and luminescence±voltage (L±V) characteristics in a computerized set-up consisting of a Newport 818SL photodetector, Keithley 238 multimeter, and Newport 835 optical powermeter.
Surface Characterization of ELCs in LEDs: Phase imaging of the sample was performed in air by tapping-mode atomic force microscope using a Nanoscope III (Digital Instruments) equipped with a ªGº scanning head. Single-beam uncoated silicon cantilevers were used (125 nm length, type TESP, Digital Instruments). Optimal imaging conditions were achieved at drive frequencies around 270 kHz, a drive amplitude of 300 mV, and scan rate of 0.5 Hz. The EL devices for AFM observation were prepared by spin-coating several drops of ELC/DDI water dispersions onto an ITO-coated glass and drying under a vacuum for 10 h.