title: Optical levitation and manipulation of stuck particles with pulsed optical tweezers.
abstract: We report on optical levitation and manipulation of microscopic particles that are stuck on a glass surface with pulsed optical tweezers. An infrared pulse laser at 1.06 microm was used to generate a large gradient force (up to 10(-9) N) within a short duration (approximately 45 micros) that overcomes the adhesive interaction between the particles and the glass surface. Then a low-power continuous-wave diode laser at 785 nm was used to capture and manipulate the levitated particle. We have demonstrated that both stuck dielectric and biological micrometer-sized particles, including polystyrene beads, yeast cells, and Bacillus cereus bacteria, can be levitated and manipulated with this technique. We measured the single-pulse levitation efficiency for 2.0 microm polystyrene beads as a function of the pulse energy and of the axial displacement from the stuck particle to the pulsed laser focus, which was as high as 88%.
authors.affiliation: Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353, USA.
authors.forename: Amol Ashok
authors.initials: AA
authors.lastname: Ambardekar
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Li
mesh_terms: D000268:Adhesiveness; D001409:Bacillus cereus / Q000166:cytology* / Q000502:physiology*; D002448:Cell Adhesion; D002465:Cell Movement / Q000502:physiology; D002469:Cell Separation / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D008846:Micromanipulation / Q000295:instrumentation* / Q000379:methods; D008863:Microspheres; D010316:Particle Size; D010812:Physical Stimulation / Q000379:methods