Study On The Secondary Flowing Etching Method Inside Microchannels Based On The Control Of Microscale Laminar Flow

This letter presents both the interface location and the molecular diffusion as a function of the flow rates at the inlets of the channel in the simplest form of the "Y-sensor", which is widely applied in the chemical extraction and biological membrane deposit. Based on theoretical analysis, we establish the numerical model of multiple laminar streams and this model matches with the visual experiment results very well. Introduce both experimental and emulational analysis of the interface position and diffusion across the two aqueous liquids in pressure-driven flow in "Y-sensor". Under the condition of keeping the flow rate at one inlet 20ml/h and the flow rate at the other inlet 2ml/h,4ml/h,8ml/h, 12ml/h,16ml/h, 20ml/h respectively, we conducted experiments and numerical simulation on the interface location. Under the condition of that the flow rates at inlets are both 2ml/h, we conducted numerical simulation on the interface diffusion and verified the simulation results through visualized experiments. Conclusions: in "Y-sensor" the ratio of stream width and the ratio of flow rates are almost equal; the diffusion extent at the interface between two streams scales as one third power of the down stream distance.Based on the research on the laminar features, this letter presents a novel micro fabrication method based on the laminar characteristics of micro-scale flows. Therein the separator and etchant are alternatively arranged in micro channels to form multiple laminar streams, and the etchant is located at the site where the reaction is supposed to occur. This new micro fabrication process can be used for the high-aspect-ratio etching inside a microchannel on glass substrates. Furthermore, the topography of microstructure patterned by this method can be controlled by changing the flow-parameters of the separator and etchant. Experiments on the effects of flow parameters on the aspect ratio, side wall profile and etching rate were carried out on a glass substrate. The effect of flow rates on the etching rate and the micro topography was analyzed. In addition, experiments with dynamical changes of the flow rate ratio of the separator and etchant showed that the vertically of the side walls of microstructures can be significantly improved. The restricted flowing etching technique not only abates the isotropic effect in the traditional wet etching but also significantly reduces the dependence on expensive photolithographic equipment.