Enhancement of microfluidic efficiency with nanocrystalline diamond interlayer in the ZnO-based surface acoustic wave device

Ultra-smooth nanocrystalline diamond (UNCD) films with high-acoustic wave velocity were introduced into ZnO-based surface acoustic wave (SAW) devices to enhance their microfluidic efficiency by reducing the acoustic energy dissipation into the silicon substrate and improving the acoustic properties of the SAW devices. Microfluidic efficiency of the ZnO-based SAW devices with and without UNCD inter layers was investigated and compared. Results showed that the pumping velocities increase with the input power and those of the ZnO/UNCD/Si devices are much larger than those of the ZnO/Si devices at the same power. The jetting efficiency of the droplet was improved by introducing the UNCD interlayer into the ZnO/Si SAW device. Improvement in the microfluidic efficiency is mainly attributed to the diamond layer, which restrains the acoustic wave to propagate in the top layer rather than dissipating into the substrate. © 2013 Springer-Verlag Berlin Heidelberg.

Multiplex detection of mutations in clinical isolates of rifampin-resistant Mycobacterium tuberculosis by short oligonucleotide Ligation assay on DNA chips

A new approach, short-oligonucleotide-ligation assay on DNA chip (SOLAC), is developed to detect mutations in rifampin-resistant Mycobacterium tuberculosis. The method needs only four common probes to detect 15 mutational variants of the rpoB gene within 12 h. Fifty-five rifampin-resistant M. tuberculosis isolates were analyzed, resulting in 87.3% accuracy and 83.6% concordance relative to DNA sequencing.

Integrated ZnO surface acoustic wave microfluidic components for biosensor

This paper describes the novel nanocrystalline film ZnO surface acoustic wave devices, which demonstrate their great potential for the portable disease diagnostic system with integrated functions of microfluidic transport, mixing and biosensing. The devices can be easily integrated with electronic control circuitry and fabricated with low temperature process on Si, glass or even polymer substrates. The liquid convection and internal streaming patterns was easily induced by acoustic wave at signal voltages. With further increase in applied voltage to above 20V, the liquid droplet was pushed forward. Immunoreaction-based bio-detection PSA/ACT, all based on SAW devices on thin film piezoelectric ZnO on Si substrate was demonstrated. © 2009 CBMS.

A Novel CMOS Color Pixel for Vision Chips

This paper presents a novel CMOS color pixel with a 2D metal-grating structure for real-time vision chips. It consists of an N-well/P-substrate diode without salicide and 2D metal-grating layers on the diode. The periods of the 2D metal structure are controlled to realize color filtering. We implemented sixteen kinds of the pixels with the different metal-grating structures in a standard 0.18 mu m CMOS process. The measured results demonstrate that the N-well/P-substrate diode without salicide and with the 2D metal-grating structures can serve as the high speed RGB color active pixel sensor for real-time vision chips well.

Measurement of 3db Bandwidth of Laser Diode Chips

An accurate technique for measuring the frequency response of semiconductor laser diode chips is proposed and experimentally demonstrated. The effects of test jig parasites can be completely removed in the measurement by a new calibration method. In theory, the measuring range of the measurement system is only determined by the measuring range of the instruments network analyzer and photo detector. Diodes' bandwidth of 7.5GHz and 10GHz is measured. The results reveal that the method is feasible and comparing with other method, it is more precise andeasier to use.

Injection by hydrostatic pressure in conjunction with electrokinetic force on a microfluidic chip

A simple method was developed for injecting a sample on a cross-form microfluidic chip by means of hydrostatic pressure combined with electrokinetic forces. The hydrostatic pressure was generated simply by adjusting the liquid level in different reservoirs without any additional driven equipment such as a pump. Two dispensing strategies using a floating injection and a gated injection, coupled with hydrostatic pressure loading, were tested. The fluorescence observation verified the feasibility of hydrostatic pressure loading in the separation of a mixture of fluorescein sodium salt and fluorescein isothiocyanate. This method was proved to be effective in leading cells to a separation channel for single cell analysis.

Determination of SARS-coronavirus by a microfluidic chip system

We have developed a new experimental system based on a microfluidic chip to determine severe acute respiratory syndrome coronavirus (SARS-Cov). The system includes a laser-induced fluorescence microfluidic chip analyzer, a glass microchip for both polymerase chain reaction (PCR) and capillary electrophoresis, a chip thermal cycler based on dual Peltier thermoelectric elements, a reverse transcription-polymerase chain reaction (RT-PCR) SARS diagnostic kit, and a DNA electrophoretic sizing kit. The system allows efficient cDNA amplification of SARS-CoV followed by electrophoretic sizing and detection on the same chip. To enhance the reliability of RT-PCR on SARS-CoV detection, duplex PCR was developed on the microchip. The assay was carried out on a home-made microfluidic chip system. The positive and the negative control were cDNA fragments of SARS-CoV and parainfluenza virus, respectively. The test results showed that 17 positive samples were obtained among 18 samples of nasopharyngeal swabs from clinically diagnosed SARS patients. However, 12 positive results from the same 18 samples were obtained by the conventional RT-PCR with agarose gel electrophoresis detection. The SARS virus species can be analyzed with high positive rate and rapidity on the microfluidic chip system.