Jiyoung Son

Non-motile sperm cell separation using a spiral channel

Microfluidic sperm sorting has historically relied on sperm motility. However, a motility-based sperm separation technology will not work when viable, non-motile sperm need to be separated from other tissues as occurs when performing testicular sperm extraction (TESE) and microdissection testicular sperm extraction (mTESE) techniques. This work demonstrates the use of inertial microfluidics technology using spiral channels to separate sperm from blood cells. The separation method, which is label-free, does not rely on sperm motility for sorting. Basic principles of spiral channel separations were used to design a specific channel and flow parameters for separating non-motile sperm from blood. The spiral channels dimensions were: initial radius, 0.7 cm; final radius, 0.899 cm; channel width, 150 μm; channel height, 50 μm; turns of spiral, 4 turns; and space between channels, 310 μm. If sperm are modeled as a 5 μm sphere, inertial microfluidics theory suggests that the sperm could be focused and separated from red blood cells (RBCs). Channels to implement these features were validated in a series of experiments. Mixed samples of RBCs and sperm were used to test the sperm separation capability of the device with the sample injection flow rate ranging from 0.1–0.52 ml min−1. After running the sample through the spiral channel, the samples were collected from four outlets and were inspected using microscopy. The best results were obtained at a 0.52 ml min−1 flow rate and generated a concentration ratio of 81%, representing the percent of sperm collected from the two outer outlets. For the same conditions, 99% of RBCs were collected from the two inner wall outlets. Using a high speed scanner, we were able to observe the focusing of the RBCs and general focusing of the sperm. As the sperm are not a uniform shape, they did not focus in a tight band, but were collected in a general region of the channel. Nevertheless, the purification ratio for these sperm was sufficient to greatly enhance the likelihood of finding rare sperm in TESE/mTESE samples containing millions of blood cells. Sequentially processing of the samples in the system proved to further improve the ratio of sperm to blood cells.

Pneumatic-less high-speed vacuum meso-pump driven by programmable hydraulics

We present the full testing and characterization results of a pneumatic-less high-speed roughing (vacuum) meso-pump that demonstrates, within our knowledge, the best near-atmosphere performance-up to date while obviating the conventional dependence on pneumatics (e.g. gas cylinders). The roughing pump operates completely all-electrically by manipulating multiple micro membranes utilizing only a single electromagnetic actuator, thus in the smallest packaged volume (22.8cc) of the same kinds while achieving a record vacuum of 206 torr within only 5 minutes. The single actuator operation is enabled by developing programmable micro hydraulics designs where multiple pump membranes were passively-controlled with designed time delays in a desired sequence. The fabricated prototype produced the maximum flow rate of 11.56 sccm at 50 Hz electromagnetic driving frequency; continually operated over 466 hours; and successfully demonstrated the timed actuation of multiple membranes utilizing only a single electromagnetic actuator.

Separation of sperm cells from samples containing high concentrations of white blood cells using a spiral channel

Microfluidic technology has potential to separate sperm cells from unwanted debris while improving the effectiveness of assisted reproductive technologies (ART). Current clinical protocol limitations regarding the separation of sperm cells from other cells/cellular debris can lead to low sperm recovery when the sample contains a low concentration of mostly low motility sperm cells and a high concentration of unwanted cells/cellular debris, such as in semen samples from patients with pyospermia [high white blood cell (WBC) semen]. This study demonstrates label-free separation of sperm cells from such semen samples using inertial microfluidics. The approach does not require any externally applied forces except the movement of the fluid sample through the instrument. Using this approach, it was possible to recover not only any motile sperm, but also viable less-motile and non-motile sperm cells with high recovery rates. Our results demonstrate the ability of inertial microfluidics to significantly reduce WBC concentration by flow focusing of target WBCs within a spiral channel flow. The estimated sample process time was more rapid (∼5 min) and autonomous than the conventional method (gradient centrifuge sperm wash; ∼1 h). A mixture of sperm/WBC was injected as the device input and 83% of sperm cells and 93% of WBCs were collected separately from two distinct outlets. The results show promise for enhancing sperm samples through inertial flow processing of WBCs and sperm cells that can provide an advantage to ART procedures such as sample preparation for intrauterine insemination.

Microfluidics: The future of microdissection TESE?

ABSTRACT Non-obstructive azoospermia (NOA) is a severe form of infertility accounting for 10% of infertile men. Microdissection testicular sperm extraction (microTESE) includes a set of clinical protocols from which viable sperm are collected from patients (suffering from NOA), for intracytoplasmic sperm injection (ICSI). Clinical protocols associated with the processing of a microTESE sample are inefficient and significantly reduce the success of obtaining a viable sperm population. In this review we highlight the sources of these inefficiencies and how these sources can possibly be removed by microfluidic technology and single-cell Raman spectroscopy.

Advances in Microfluidics and Lab-on-a-Chip Technologies

Abstract Advances in molecular biology are enabling rapid and efficient analyses for effective intervention in domains such as biology research, infectious disease management, food safety, and biodefense. The emergence of microfluidics and nanotechnologies has enabled both new capabilities and instrument sizes practical for point-of-care. It has also introduced new functionality, enhanced sensitivity, and reduced the time and cost involved in conventional molecular diagnostic techniques. This chapter reviews the application of microfluidics for molecular diagnostics methods such as nucleic acid amplification, next-generation sequencing, high-resolution melting analysis, cytogenetics, protein detection and analysis, and cell sorting. We also review microfluidic sample preparation platforms applied to molecular diagnostics and targeted to sample-in, answer-out capabilities.