Bingqiang Ren

Multiplexed bead-based mesofluidic system for gene diagnosis and genotyping.

We have developed a novel multiplexed bead-based mesofluidic system (MBMS) based on the specific recognition events on the surface of a series of microbeads (diameter 250 μm) arranged in polydimethylsiloxane (PDMS) microchannels (diameter 300 μm) with the predetermined order and assembled an apparatus implementing automatically the high-throughput bead-based assay and further demonstrated its feasibility and flexibility of gene diagnosis and genotyping, such as β-thalassemia mutation detection and HLA-DQA genotyping. The apparatus, consisting of bead-based mesofluidic PDMS chip, liquid-processing module, and fluorescence detection module, can integrate the procedure of automated-sampling, hybridization reactions, washing, and in situ fluorescence detection. The results revealed that MBMS is fast, has high sensitivity, and can be automated to carry out parallel and multiplexed genotyping and has the potential to open up new routes to flexible, high-throughput approaches for bioanalysis.

Design and application of fiber optic evanescent wave biosensor

A fiber-optic biosensor is developed based on the principle of evanescent wave while light propagates in optical fiber. The biosensor uses a red laser diode at 636.85 nm for exciting Cy5 fluorescent dye. Sensitivity limit of 0.01 nnmol/l is obtained from the detection of serial Cy5 solutions with various concentrations. In log-to-log plot, excellent linear response characteristic is seen in the Cy5 concentrations ranging from 0.01 nmlo/l to 100 nmol/l. And a good result of signal-to-noise ratio of 4.61 is obtained when the biosensor is used to measure Legionella pneumophila solution of 0.01 μmol/l. All the results are comparable with those that are obtained by a commercial biochip scanner GeneTAC 1000.

Design of time-resolved fluorometer based on immunochromatography

This paper introduces the design of a novel time-resolved fluorometer based on immunochromatograghy. Different from the other time-resolved fluorometers, it tests the immunochromatographic strip which is labeled with lanthanide ions and their chelates. This instrument can provide a rapid, quantitative measurement of analytes present in samples without any washing steps and it can be used to carry out point-of-care test (POCT). The immunochromatograghy-based timeresolved fluorometer is composed of a specific optical sensor, a scanning stage, a signal processing system and a computer control system. The light from UV LED is focused on the test strip by a condense lens group in the optical sensor. If the labels are present in samples, the fluorescence at 613nm will be exited (when Eu3+chelate is used for marking substance). After a delay of some microseconds, the fluorescence will be collected by the optical sensor and converted into electronic signal by a photomultiplier tube (PMT). The concentration of the sample can be calculated through the standard working curve of this instrument. By testing, the sensitivity is several ng/ml level (when Eu3+chelate is used for marking substance), test linear range is from several ng/ml to 103 ng/ml, in which correlation coefficient is 99.97%.

A miniaturized laser-diode-based optical sensor for laser particle counter

A miniature optical sensor for laser particle counter is described, and some calculated and test results are reported in this paper. A reflective spherical mirror coated with highly reflective optical film is applied as collecting element for scattered light, and a PIN photodiode with high performance is used as the photo-detector. A band-pass preamplifier is used to eliminate lower-frequency electromagnetic interference from external environment, as well as to filter high-frequency components from electronic noise. An air sampling system can provide a very constant flow rate. The smallest particle diameter of the optical sensor is 0.3 microns with a signal-to-noise ratio exceeding 2:1.

The beam delivery modeling and error sources analysis of beam stabilization system for lithography

Beam stabilization system is one of the most important units for lithography, which can accomplish displacement and pointing detection and control and includes beam measurement unit(BMU) and beam steering unit(BSU). Our group has set up a beam stabilization system and verified preliminarily beam stabilization algorithm of precise control beam position and angle. In the article, we establish beam delivery mathematic model and analyze the system inherent error. This shows that the reason why image rotation effect arises at the output plane of beam stabilization is the fast steering mirror (FSM) rotation of BSU in the process of beam stabilization. Two FSMs rotation around 45o axis of FSM make the most contribution to image rotation which rotates 1.414 mrad as two FSMs rotation angle difference changes 1 mrad. It is found that error sources include three key points: FSM accuracy; measurement noise and beam translation by passing through of beam splitters changing as the ambient temperature changing. FSM accuracy leads to the maximum 13.2μm displacement error and 24.49μrad angle error. Measurement inaccuracy as a result of 5μm measurement noise results in the maximum 0.126mm displacement error and 57.2μrad angle error. Beam translation errors can be negligible if temperature is unchanged. We have achieved beam stability of about 15.5μrad for angle and 28μm for displacement (both 1σ) after correcting 2mm initial displacement deviation and 5mrad initial angle deviation with regard to the system rebuilt due to practical requirements.

UPT-based biosensor and its application

An up-converting phosphor technology-based biosensor (UPT-based biosensor) has been developed for immunoassay using Up-converting phosphor (UCP) as the biological marker. The UPT system has realized quantitative detection and has good ability to meet the need of some emergencies. High sensitivity (nanogram/ml), good linear response characteristics and an excellent correlation (R2greater than or equal to 0.95) have been verified by quantitative detection results. The sensitivity of the UPT-based biosensor is better than that of the indirect hemagglutination test in the practical application. All the results are comparable with that obtained by Western Blot detection.

Performance test of focusing optics based on the Hartmann principle

The performance inspection of focusing optics, such as focusing lens and focusing assemblies, is of great importance in the machining of optical elements, alignment and regular maintenance of optical facilities. Currently, however the interferometric method and the knife-edge method used normally for the measurement of the large-aperture surface have limitations for the test in the large optical equipment. To solve the problems, a scanning Hartmann inspection apparatus based on the Hartmann principle for focusing optics performance test has been developed. In this paper, the experimental setup and test principle are described, experimental results and analysis are given, and the improvement plan further to obtain better test capability is briefly presented in the end.