Biomedical subjects

Yi-Yu Chen

Publications and source records attributed to Yi-Yu Chen.

3 recordsLinked to original sources

PubMed2006

Integrated polymerase chain reaction chips utilizing digital microfluidics.

This study reports an integrated microfluidic chip for polymerase chain reaction (PCR) applications utilizing digital microfluidic chip (DMC) technology. Several crucial procedures including sample transportation, mixing, and DNA amplification were performed on the integrated chip using electro-wetting-on-dielectric (EWOD) effect. An innovative concept of hydrophobic/hydrophilic structure has been successfully demonstrated to integrate the DMC chip with the on-chip PCR device. Sample droplets were generated, transported and mixed by the EWOD-actuation. Then the mixture droplets were transported to a PCR chamber by utilizing the hydrophilic/hydrophobic interface to generate required surface tension gradient. A micro temperature sensor and two micro heaters inside the PCR chamber along with a controller were used to form a micro temperature control module, which could perform precise PCR thermal cycling for DNA amplification. In order to demonstrate the performance of the integrated DMC/PCR chips, a detection gene for Dengue II virus was successfully amplified and detected. The new integrated DMC/PCR chips only required an operation voltage of 12V(RMS) at a frequency of 3 KHz for digital microfluidic actuation and 9V(DC) for thermal cycling. When compared to its large-scale counterparts for DNA amplification, the developed system consumed less sample and reagent and could reduce the detection time. The developed chips successfully demonstrated the feasibility of Lab-On-a-Chip (LOC) by utilizing EWOD-based digital microfluidics.

Dengue Virus↗

PubMed2006

Transverse vibration analysis for piezoceramic rectangular plates using Ritz's method with equivalent constants.

The transverse vibration of piezoceramic rectangular thin plates is investigated theoretically and experimentally using the Ritz's method incorporated with the defined equivalent constants. The equivalent constants are derived by comparing the characteristic equations of transverse resonant frequencies between isotropic and piezoceramic disks. By replacing the Poisson's ratio and flexural rigidity with the equivalent constants, the well-known Ritz's method can be used to investigate the transverse vibration of piezoceramic rectangular plates. Two different types of boundary conditions-clamped-free-free-free (CFFF) and clamped-free-clamped-free (CFCF)-are analyzed in this paper. For the experimental measurement, two optical techniques-amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV)-are used to validate the analytical results. Both the transverse vibration modes and resonant frequencies of piezoceramic rectangular plates are obtained by the AF-ESPI method. Numerical calculations using the finite-element method (FEM) are performed, and the results are compared with the theoretical analysis and experimental measurements. Excellent agreements are obtained for results of both resonant frequencies and mode shapes. According to the theoretical calculations with different equivalent Poisson's ratios, resonant frequency variations versus aspect ratios ranging from 0.1 to 10 also are discussed for the first several modes in the work.

Journal Article↗

PubMed2005

[Phylogeny of chinese catfishes inferred from mitochondrial cytochrome b sequences].

The mitochondrial DNA cytochrome b gene was sequenced from 27 catfish species representing 11 families and 24 genera catfishes in China. Aligning with cytochrome b sequences of eight catfish species from North America and Africa retrieved from GenBank, and selecting Astyanax mexicanu, Cyprinus carpio, and Sardinops melanostictus as outgroups, we constructed a matrix of 38 DNA sequences. The phylogenetic trees were constructed by using Bayesian method and Maximum Parsimony (MP) method. The results showed that (1) there are three base pair deletions of mitochondrial cytochrome b gene compared with Characiformes, Cypriniformes, and Clupeiformes; (2) the representatives of Chinese catfish species form a monophyletic group; and (3) the molecular phylogenetic trees constructed with both methods suggest that the families Sisoridae, Akysidae and Amblycipitidae form a monophyletic group, and the families Clariidae, Schilbidae, Ariidae, Ictaluridae, Cranoglanididae, Pangasiidae, Siluridae, Claroteidae, and Bagridae also form a monophyletic group. The families Cranoglanididae from China and Ictaluridae from North America form a sister-group relationship, and the families Clariidae, Ictaluridae, Siluridae, and Sisoridae are obviously monophyletic groups. But the position of the family Plotosidae was not resolved by Bayesian analysis and maximum parsimony inference.

Animals↗