Related Experiment Video
Updated: Aug 1, 2026
10:02
Two Types of Assays for Detecting Frog Sperm Chemoattraction
Published on: December 27, 2011
19.1K
Qualified sperm selection based on the rheotaxis and thigmotaxis in a microfluidic system
Nima Ahmadkhani1, Maryam Saadatmand1, Somaieh Kazemnejad2
1Department of Chemical and Petroleum Engineering, Sharif University of Technology, 11155-9465, Tehran, Iran.
Biomedical Engineering Letters
|October 24, 2023
Summary
This study developed a microfluidic system for sperm separation, mimicking the female reproductive tract. Sinusoidal geometry enhanced sperm quality for assisted reproductive technology by utilizing rheotaxis and thigmotaxis.
Area of Science:
- Biomedical Engineering
- Reproductive Biology
- Microfluidics
Background:
- Assisted reproductive technology (ART) requires high-quality sperm.
- Current sperm separation methods face limitations.
- Microfluidic systems offer a promising approach to mimic the female reproductive tract (FRT) for improved sperm selection.
Purpose of the Study:
- To design and fabricate a microfluidic system for passive sperm separation.
- To investigate the combined effects of rheotaxis and thigmotaxis on sperm quality.
- To identify optimal microchannel geometry for enhanced sperm separation.
Main Methods:
- Fabrication of a PDMS-based microfluidic system with four geometries: linear, square, zigzag, and sinusoidal.
- Utilizing rheotaxis (flow-induced movement) and thigmotaxis (wall-following behavior) for passive separation.
- Evaluation of sperm functionality using sperm tracking (ImageJ), motility assay (CASA software), and morphology assay (Papanicolaou ultrafast staining).
Main Results:
- All tested microchannel geometries yielded 100% motile sperm.
- Non-linear geometries (sinusoidal, zigzag, square) were more effective than linear geometry in separating progressive, high-quality sperm.
- The sinusoidal geometry demonstrated the highest enhancement, resulting in separated sperm with 34.7% normal morphology, 100% motility, and 100% viability.
- Dead zones in square and zigzag geometries hindered sperm progression towards the outlet.
Conclusions:
- Periodic changes in sperm position, influenced by wall interactions and flow, are crucial for high-quality sperm separation.
- The sinusoidal microchannel geometry is the most effective design for sperm separation, significantly improving morphological quality.
- Microfluidic systems mimicking FRT features, particularly sinusoidal designs, represent a significant advancement for assisted reproductive technology.
Related Concept Videos
01:09Radiation Pressure: Problem Solving
The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave's momentum also gets transferred to the surface when an electromagnetic wave is entirely absorbed by it. The rate at which momentum is transmitted to an absorbing surface perpendicular to the propagation direction equals the force on the surface.
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
01:18Drag Force and Terminal Speed
An interesting force in everyday life is the force of drag on an object when it is moving in a fluid. Like friction, the drag force always opposes the motion of an object. Unlike simple friction, the drag force is proportional to some function of the velocity of the object in that fluid. This functionality is complicated and depends upon the shape of the object, its size, its velocity, and the fluid it is in. For most large objects, such as cyclists, cars, and baseballs, that are not moving too...
01:18Newtonian Fluid: Problem Solving
Newtonian fluids exhibit a constant viscosity, meaning their shear stress and shear strain rate are directly proportional. This property ensures a predictable and stable response to applied forces, maintaining a linear relationship between force and flow. Examples include water, air, and light oils, consistently demonstrating this proportional behavior regardless of external conditions.
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
01:30Typical Model Studies
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.
01:26General External Flow Characteristics
The study of external flow is essential for creating structures and objects that interact efficiently and safely with moving fluids, such as air or water. When a body is immersed in a flowing fluid, it experiences two primary forces: drag, which opposes motion along the flow direction, and lift, which acts perpendicular to the flow. The shape, size, and orientation of the object influence these forces.Streamlined and Blunt Bodies in External FlowObjects in fluid flow are classified as...
01:23Drag
Drag is a resistive force opposing an object’s motion through a fluid, resulting from surface pressure and shear forces. It comprises two components: a perpendicular one from pressure and a tangential one from shear stress. Accurate drag calculations use pressure and wall shear stress distributions, often determined through Computational Fluid Dynamics (CFD) or wind tunnel testing. The drag coefficient, a dimensionless measure, depends on factors like shape, Reynolds number, Mach number, Froude...