Micromanipulation of sperm by a laser generated optical trap

Area of Science:

• Biophysics
• Reproductive Biology
• Microfluidics

Background:

• Optical traps utilize laser radiation pressure to create forces capable of manipulating microscopic objects.
• Spermatozoa manipulation is crucial for assisted reproductive technologies and andrological research.
• Understanding the impact of external forces on sperm motility is essential for evaluating reproductive potential.

Purpose of the Study:

• To investigate the effects of optical trapping on sperm motility.
• To assess the feasibility of using optical tweezers for sperm micromanipulation.
• To determine the threshold for detrimental effects of optical traps on sperm function.

Main Methods:

• A low-power Nd:YAG laser was integrated with a microscope to generate an optical trap.
• Spermatozoa were captured and manipulated using a joystick-controlled motorized stage within the optical trap.
• Computerized image processing analyzed sperm velocity and movement patterns after varying exposure times.

Main Results:

• Minor changes in sperm velocity were observed for exposure periods of 30 seconds or less.
• A gradual decrease in mean linear velocity was noted after 45 seconds of optical trap exposure.
• The optical micromanipulator demonstrated capability for precise sperm handling.

Conclusions:

• Optical traps can be used for sperm manipulation with minimal short-term effects on motility.
• Prolonged optical trap exposure negatively impacts sperm velocity, indicating a potential stressor.
• This technique offers a valuable tool for studying single sperm mechanics and drug-induced motility changes.