ABSTRACT
Until now, a swim-up or microchip-based method has been mainly utilized for separating normal sperm for use in assisted reproductive technology. However, it requires excessive sorting time due to preprocessing and collects a limited number of motile sperms. To improve this process, we propose a gravity-fed high motility sperm sorting device that utilizes the rheotaxis of sperm, which minimizes separation time and improves throughput. The device features a mesoscale microfluidic channel to maximize the throughput, and an outlet at the bottom is configured to control the fluid velocity in the channel by using gravity. To control and automate semen injection and suction of the sorted sperm, a pipette controller using a cam was fabricated. After constructing the system, a sorting experiment was performed using canine semen to confirm the separation efficiency. After injecting the semen in the channel, the delay time between injection and suction was measured and the relative improvement of the index of motility was investigated according to measured delay time. As a result of repeated experiments, it was confirmed that the highest improvement was obtained at a delay time of 80 s, and the mean velocity, %motility, MI, and motile sperm rates were improved by 8.94%, 32.58%, 35.48%, and 21.99%, respectively.
ABSTRACT
BACKGROUND: At present, the colonoscopy is the most common method of screening for colorectal cancer. However, endoscopists still encounter difficulties with intubation, primarily due to the structural diversity (e.g., path, shape, and size) and viscoelasticity of the colon. Therefore, well-trained, skillful operators are required to overcome these factors and operate colonoscopes without harming patients. OBJECTIVES: In our previous work, we presented a reel mechanism-based robotic colonoscope designed to mitigate the difficulties of conventional colonoscopies. Although we reported excellent mobile performance with respect to the robot, we did not provide an in-depth discussion concerning patient safety. Therefore, in this article, we propose a method of improving robot safety, and this is verified by investigating the static and dynamic forces acting on the colon. In addition, the maneuverability and safety of the robot in the in vitro condition are evaluated. METHODS: The safety solution is provided by covering the robot's legs with silicone. To evaluate the results, the reaction force according to leg deformation is measured. Then, the force transmitted to the colon is also measured when the robot moves through various environments. Finally, a mobility test on an excised porcine colon is performed to simultaneously verify the robot's maneuverability and safety. RESULTS: We verify that the static and dynamic force acting on the colon is less than the burst force of a human colon. In addition, the maneuverability of the robotic colonoscope shows reliable locomotion performance even with the soft material covering the legs; it has forward velocities of 9.552 ± 1.940 mm/s on a flat path. CONCLUSION: Owing to the reliable locomotion mechanism with the safety-securing silicone, the robot achieves high and reliable maneuverability without any scratches or perforations to the porcine colon.
