•  3
    High-throughput sorting and analysis of human sperm with a ring-shaped laser trap
    with B. Shao, L. Z. Shi, E. L. Botvinick, M. Ozkan, M. W. Berns, and S. C. Esener
    Sperm motility is an important concept in fertility research. To this end, single spot laser tweezers have been used to quantitatively analyze the motility of individual sperm. However, this method is limited with throughput, lacks the ability of in-situ sorting based on motility and chemotaxis, requires high laser power and can not be used to dynamically monitor changes in sperm swimming behavior under the influence of a laser beam. Here, we report a continuous 3-D ring-shaped laser trap which …Read more
  •  2
    Chemosensory Ca 2+ dynamics correlate with diverse behavioral phenotypes in human sperm
    with T. Veitinger, Riffell Jr, S. Veitinger, A. Triller, C. Chandsawangbhuwana, K. Schwane, A. Geerts, F. Wunder, M. W. Berns, E. M. Neuhaus, R. K. Zimmer, M. Spehr, and H. Hatt
    In the female reproductive tract, mammalian sperm undergo a regulated sequence of prefusion changes that "prime" sperm for fertilization. Among the least understood of these complex processes are the molecular mechanisms that underlie sperm guidance by environmental chemical cues. A "hard-wired" Ca2+ signaling strategy that orchestrates specific motility patterns according to given functional requirements is an emerging concept for regulation of sperm swimming behavior. The molecular players inv…Read more
  •  2
    Dynamically adjustable annular laser trapping based on axicons
    with B. Shao, S. C. Esener, E. L. Botvinick, and M. W. Berns
    To study the chemotactic response of sperm to an egg and to characterize sperm motility, an annular laser trap based on axicons is designed, simulated with the ray-tracing tool, and implemented. The diameter of the trapping ring can be adjusted dynamically for a range of over 400 μm by simply translating one axicon along the optical axis. Trapping experiments with microspheres and dog sperm demonstrate the feasibility of the system, and the power requirement agrees with theoretical expectation. …Read more
  •  2
    The combination of laser tweezers, fluorescent imaging, and real-time automated tracking and trapping can measure sperm swimming speed and swimming force simultaneously with mitochondrial membrane potential. This approach is used to study the roles of two sources of ATP in sperm motility: oxidative phosphorylation, which occurs in the mitochondria located in the sperm midpiece and glycolysis, which occurs along the length of the sperm tail. The relationships between swimming speed and MMP and sw…Read more
  • Real-time automated tracking and trapping system for sperm
    with L. Z. Shi, C. Chandsawangbhuwana, M. W. Berns, and E. L. Botvinick
    We have developed a microscope system for real-time single sperm tracking with an automated laser tweezers escape power assay. Phase contrast images of swimming sperm are digitized to the computer at video rate. The custom algorithm creates a region of interest centered about a sperm in response to a mouse click and performs all subsequent tasks autonomously. Microscope stage movement responds to feedback from video analysis of swimming sperm to center the sperm with respect to the field of view…Read more
  • The use of optical tweezers to study sperm competition and motility in primates
    with L. Z. Shi, S. Meyers, P. Gagneux, N. M. Loskutoff, E. L. Botvinick, and M. W. Berns
    Optical trapping is a non-invasive biophysical tool which has been widely applied to study physiological and biomechanical properties of cells. Using laser 'tweezers' in combination with custom-designed computer tracking algorithms, the swimming speeds and the relative swimming forces of individual sperm can be measured in real time. This combination of physical and engineering tools has been used to examine the evolutionary effect of sperm competition in primates. The results demonstrate a corr…Read more