Research On Detection Technologies Used In Suspension Biochip

The biochip technology is a cross field where many subjects are involved. It is divided into two kinds from its configuration: the slice biochip and suspension biochip. The application of the slice biochip is confined greatly by its complicated manufacture procedure and its high cost, especially blocking it off from clinic use. The particular flexibility of the suspension biochip made it possible that the suspension biochip could realize its industrialization from laboratory rapidly, especially the clinical diagnosis. The biochip experiments were based on the hybridization reaction. The test sample was tagged with the fluorescent dyes and hybridized with the structured biochip sufficiently .The hybridization reaction fluorescent signal is analyzed by detection apparatus lastly. So the detection technology is the key factor of biochip application.The existing suspension technology which was employing one dimension detection method based on the cytometry was introduced at first ,then the configuration and detection principle of the suspension biochip ,which is designed by us, is described .There are micro-fluidic system .optical system and signal processing system in the suspension biochip detection system .The novel design of two dimension micro-fluidic field and two dimension testing method were presented firstly for enhancing its analysis speed. With adopting CCD coagulate imaging method and parallel detection method, the analysis output was enhanced greatly. The cost of the suspension biochip detection apparatus was reduced by adopting brief configuration design of the fluorescence analysis system enormously.Micro-fluidic field system is composed by micro channel and sample driving device .Three kinds of methods were employed in fabricating different size micro channels: mechanical way, laser ablation and etching .The characteristics of those channels were analyzed from experiment results .The macroscopical movement character of micro-beads in fluidic field was analyzed theoretically .The states of static and moving micro-beads were observed by experiment .The conclusion of micro-beads moving stably in fluidic was obtained lastly.Optical system is composed of excitation optical system, fluorescence collection imaging system and filters .The excitation light beam was projected to the test area of micro channel by excitation optical system in order to excite fluorescent dyes tagged in the micro-beads .Thefluorescence signal came from micro-beads in the test area was collected and the test area was imaged to CCD at same time by the fluorescence imaging system .The excitation light and fluorescence were distinguished and selected by excitation and emission filters . The design demands and the conflicting relation among the parameters of the optical system were presented.The relation between the sensitivity and the each parameter of the detection system was analyzed in detail from the view of conventional fluorescence testing system configuration .The formula of sensitivity of fluorescence detection system was obtained .The system sensitivity of our suspension biochip analysis was estimated about 7.9 fluors/μm~2 and it was validated by experiment.The Optical characters of the biochip detection system is scaled by following four parameters: spatial resolution, depth of field, working distance and field of view. The conflicting relation of the four parameters were analyzed and the suspension biochip detection method was presented by using the multi-beam interferential illumination .The conclusion resulted from theoretical analysis is that the longer working distance , wider field of view and ideal depth of field was obtained ,the spatial resolution was not restricted by the NA at same time by using smaller aperture collecting lens and bigger angle of the cone of illumination beams .The flexibility of biochip analysis was enhanced greatly and it is easier to obtain the fluorescence signal as a result of higher intensity of excitation light.