Abstract
The methods applied in separating sperms in microfluidic bio-chip can divide in steady laminar flow and reversing flow. Due to motile sperms can across the original laminar to the selection laminar, the motile sperms can be collected in the outlet. The disadvantage of the former way is that we can not tell the sperms motility apart. Sperms can against the flow by nature property, thus, separating the motile sperms by using reversing flow can select motile sperms. However the shearing force in the reversing flow will cripple the sperms motility. The thesis presents a novel chip that diffuser type channel will slow down the fluidic velocity in channel, the motile sperm will stay in the chamber owe to their nature property and the non-motile ones will drift to outlet with flow. By controlling the flow velocity in channel can select the motility of sperm which stayed in channel. The motility of sperm will not cripple, the classification of sperm can be determined as well. The thesis presents a novel diffuser type microfluidic chip, based on the sperm can against the fluidic. We use the forward flow instead of the reverse flow to reduce the distance which sperm swims to expanding area. The fluidic velocity in channel will decrease with the vary channel width. The channel width in 100μm increase to 1000μm and the diffuse angle is 5∘. The motile sperm can against flow and stay in the channel while non-motile sperm will drift to the outlet. The fluidic driving force can be concluded into “pressure height passive way” and “continuous steady pressure active way”. The pressure height in 2mm can generate the fluidic velocity in 240μm/s in the passive way and the sperms will stay at the specific position based on their positions. Setting the syringe pump flow rate at 0.0648ml/hr in the active way and the velocity can be calculated into 180μm/s. There are two way can be applied to take the sperm out. One way is by controlling the fluid velocity. The nonmotile sperm can be washed out at the first time while the motile sperm can be washed out at the second time. Another way is adding two branches at the expanding area and the sperm will be taken out from the branches. As the results show, the live and dead ratio in passive way reaches in 78.7% and the live sperm taken from the branches ups to 84.8%. The thesis presents a microfluidic device can separate the motile sperm but not to hurt the sperm moltility, moreover the sperm motility can be classfied. It can be considered as multi-criterion separation chip.