Assisted reproductive technology includes medical procedures that confront the problem of infertility. In some cases of male infertility, blood cells are present in the sperm containing samples and must be removed. Spiral-channel devices have been developed to perform this task, but there is a strong need to increase their throughput. In this work, the theory behind the separation is employed to optimize the device for increased throughput. An existing device that is known to separate sperm and blood cells with a rectangular cross section of 600 × 100 μm² was used as the baseline. Using its physics, theoretical models were generated to explore theoretical performances of larger-size channels. The models suggested that a channel of size 800 × 133 μm² would likely work. This geometry enabled the throughput to be increased by 50%, from 2 ml/min in the case of the baseline-size to 3 ml/min in the designed device. Experiments using the larger device resulted in a recovery of more than 90% of sperm cells while removing 89% of red blood cells (RBCs). In comparison, the reference device results in a 90% recovery of sperm cells while removing 74% of white blood cells (WBCs). The length of the channel was also reduced to reduce the pressure required to operate the chip. Literature has shown the removal of WBCs to be higher than that of RBCs due to their larger size, spherical shape, and comparatively low deformability, suggesting that the revised chip would be faster and better for the separation of sperm and all blood cells.

In-vitro spermatogenesis holds great potential in addressing male infertility, yet one of the main challenges is separating round spermatids from other germ cells in spermatogonial stem cell cultures. STA-PUT, a method based on velocity sedimentation, has been extensively tested for this application. Though somewhat effective, it requires bulky, expensive equipment and significant time. In contrast, the method of inertial microfluidics offers a compact, cost-effective, and faster alternative. In this study, we designed, fabricated, and tested a microfluidic spiral channel for isolating round spermatids and purifying spermatogenic cells. A commercially available spiral device close to the calculated specifications was tested for rapid prototyping, achieving 79% purity for non-spermatid cells in a single pass, with ability to achieve higher purity through repeated passes. However, the commercial device’s narrow outlets caused clogging, prompting the fabrication of a custom polydimethylsiloxane device matching the calculated specifications. This custom device demonstrated significant improvements, achieving 86% purity in a single pass compared to STA-PUT’s 38%, and that without any clogging issues. Further purification could be attained by repeated passes, as shown in earlier studies. This work underscores the efficacy of inertial microfluidics for efficient, high-purity cell separation, with the potential to revolutionize workflows in in-vitro spermatogenesis research.

Collecting cells from zebrafish embryos for genotyping is critical to rapid research with these model organisms. The standard collection process is manual, labor-intensive, time-consuming, and requires a skilled person to perform it. To overcome this challenge, researchers are exploring the development of automated genotyping tools for live animals, which would significantly enhance the efficiency and accuracy of genetic screening in zebrafish and other species. The focus of this research was to optimize the Zebrafish Embryo Genotyper (ZEG), an automated system used for the rapid extraction of cellular material from zebrafish embryos. This system rapidly vibrates a roughened chip containing a zebrafish embryo to collect genetic material safely and efficiently. The aim was to improve the efficiency of DNA collection from the chips used with the ZEG by identifying the key factors that contribute to the process. First, the chips were modified to resolve issues associated with loss of sample volume from the chip wells due to evaporation during processing. Second, we experimented with three critical parameters – sample volume in the wells, the vibrational frequency of the system, and the operation time – on the quantity of DNA collected. The performance was evaluated by measuring embryo survival and quantifying the DNA collected. The sensitivity (previously 90%) of the DNA collection and embryo survival (previously 95%) of the were both found to be greater than 95% after optimization. The optimized design parameters (15 µL solution volume, 2.4 V, and a 5-minute run with 5 s alternating on/off) provided a >50% increase in DNA collection compared to the previous designs and parameters. The proposed chip design and operation do not appear to cause any apparent adverse effects on the development or survival of the embryos.

A sperm racetrack device that competes sperm against each other by swimming speed. We show that the device successfully separates sperm into faster and slower aliquots using computer-aided sperm analysis.