jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Sep 2008

Volume 104, Issue 6, Articles (06xxxx)

Return to All Sections
back to top
RSS Feeds

Single-narrow-band red upconversion fluorescence of ZnO nanocrystals codoped with Er and Yb and its achieving mechanism

Yunxin Liu, Qibin Yang, and Changfu Xu

J. Appl. Phys. 104, 064701 (2008); http://dx.doi.org/10.1063/1.2980326 (5 pages) | Cited 9 times

Online Publication Date: 24 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
ZnO nanocrystals doped with Er3+ and Yb3+ ions were synthesized by the chemical-combustion process. The single-narrow-band red fluorescence (centered at 662 nm) in ZnO:Er, Yb was observed under 115 mW excitation of a 980 nm laser diode. The full width at half maximum of the red emission band is equal to 30 nm, which is the narrowest emission band ever reported in Er3+ doped systems. This narrower emission band in ZnO:Er, Yb nanocrystal is beneficial for improving the precision and sensitivity of the indicators in fluorescent label detection. The mechanisms resulting in the single-narrow emission band were analyzed by combining X-ray diffraction, Raman spectra, fluorescence spectra, and a simple model.
Show PACS
78.55.Et II-VI semiconductors
81.05.Dz II-VI semiconductors
61.72.uj III-V and II-VI semiconductors

Simulation on binding efficiency of immunoassay for a biosensor with applying electrothermal effect

Kuan-Rong Huang, Jeng-Shian Chang, Sheng D. Chao, Kuang-Chong Wu, Chih-Kai Yang, Cheng-Yu Lai, and Shyh-Haur Chen

J. Appl. Phys. 104, 064702 (2008); http://dx.doi.org/10.1063/1.2981195 (11 pages) | Cited 3 times

Online Publication Date: 25 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The working principle of immunoassays is based on the specific binding reaction of an analyte-ligand protein pair in physiological environments. However, for a diffusion-limited protein, the diffusion boundary layer of the analyte on the reaction surface of a biosensor would hinder the binding reaction from association and dissociation. The formation of such association and dissociation layers thus limits the response time and the overall performance of a biosensor. In this work we have performed a two-dimensional full time scale finite element simulation on the binding reaction kinetics of two commonly used proteins, C-reactive protein (CRP) and immunoglobulin G (IgG). By applying a nonuniform ac electric field to the flow microchannel of the biosensor, the electrothermal force can be generated to induce a pair of vortices to stir the flow field. With the aid of the vortices and a suitable choice of the location of the biosensor, the fluids flowing over the reacting surface can be accelerated fast enough to depress efficiently the growth of the diffusion boundary layer on the reaction surface, and enhance the association or dissociation of analyte-ligand complex. The interference patterns of the flow field due to the existence of the sensor at different locations of the microchannel could cause different degrees of enhancement to the association and the dissociation. By changing the location of the sensor the largest enhancement is found at the position near the negative electrode. For the configuration of the microchannel we studied, the initial slope of the curve of the analyte-ligand complex versus time can be raised up to 5.17 for CRP and 1.93 for IgG in association, and 3.74 for CRP and 1.28 for IgG in dissociation, respectively, under the applied ac field 15 Vrms peak-to-peak and operating frequency 100 kHz. At this optimal sensor location, we also studied the effect of various settings of temperature boundary conditions on the top and bottom walls, including the two limiting cases, namely, constant temperature and thermal insulation on both walls. We show that varying the temperature boundary conditions can cause an essential effect on the enhancement of the binding reaction and can be employed to find an optimal binding enhancement. Utilizing these simulation results, an improved design incorporating a pair of electrodes and a neck region near the reaction surface is demonstrated. The sensor is fixed to locate at the middle of the bottom side. With the existence of the stirring flow field, the association rate of the 30 μm neck is 2.73 times faster than that of the original channel with no neck.
Show PACS
87.85.Ox Biomedical instrumentation and transducers, including micro-electro-mechanical systems (MEMS)
87.14.E- Proteins
87.15.R- Reactions and kinetics
87.10.Kn Finite element calculations
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close