ABSTRACT
Objectiye To optimize the depth of the microchannel and the time point for sperm collection,and improve the efficiency of sperm screening on a microfluidic device. Methods Microchannels with four different depths of 25, 50, 100 and 200 μm were tested. Mice sperm were added to the inlet of the microchannel. The relative quantity and motility of sperm in the outlet were recorded at different collection times, i.e. ,5, 15, 30 and 60 min. Statistical method one-way ANOVA and appropriate post-hoc testing were applied to analyze differences between different groups, and further to select the best-fit depth of the microchannel and the time point for collection. Results In microchannels with depths of 25, 50, 100 and 200 μm, the sperm motilities measured in each outlet were (85.4 ± 2.3)%, (85.8 ± 5.8)%,( 87. 2 ± 2. 8 ) %, (76. 5 ± 2. 8 ) % respectively with statistical significance ( F = 5.8, P ＜ 0. 05 ). No obvious differences were found among 25-100 μm channels, however the motility dramatically decreased in the 200 μm group. The relative sperm quantities were (5.2 ±2.0)%, (7.2 ±2.5)%,(12.3 ±2.0)%,(7. 7 ± 1.1 ) % respectively with statistical significance ( F = 6. 9, P ＜ 0. 05), which increased with channel depth from 25 to 100 μm,while it decreased in the 200 μm channel Taking 2 indexes into account, 100 μmwas the most fit channel depth for sperm motility screening. The sperm motility in the outlet gradually decreased with time. At the time points of 5, 15, 30 and 60 min after adding sperm, the sperm motilities were (99. 6 ±0. 7)%, (87.2 ±2. 8)%, (79. 3 ±2. 2)% and (62. 6 ±8.0)% respectively with statistical significance ( F = 37. 3, P ＜ 0. 01 ). Yet the relative quantities of sperm in the outlet increased almost three times in this process. At the time points mentioned above, the relative quantities of sperm were (5.8±1.1)%, (10.6 ± 0.9)%, (12.1 ± 1.7)%, (17.9 ± 3.4)% respectively with statistical significance ( F = 17.8, P ＜ 0. 01 ). Thus 15-30 min was the ideal screening time. Conclusion An effective microdevice for sperm screening with optimized depth and collection time period is developed,which may contribute significantly for the screening of healthy sperm on microfluidic chips.