Incoherent Optical Tweezers on Black Titanium

Abstract

Optical tweezers enable the manipulation of micro- and nanodielectric particles through entrapment using a tightly focused laser. Generally, optical trapping of submicron size particles requires high-intensity light in the order of MW/cm2. Here, we demonstrate a technique of stable optical trapping of submicron polymeric beads on nanostructured titanium surfaces (black-Ti) without the use of lasers. Fluorescent polystyrene beads with a diameter d = 20–500 nm were successfully trapped on black-Ti by low-intensity focused illumination of incoherent light at λ = 370 m from a Hg lamp. Light intensity was 5.5 W/cm2, corresponding to a reduced light intensity of 6 orders of magnitude. Upon switching off illumination, trapped particles were released from the illuminated area, indicating that trapping was optically driven and reversible. Such trapping behavior was not observed on nonstructured Ti surfaces or on nanostructured silicon surfaces. Thus, the Ti nanostructures were demonstrated to play a key role.

Bactericidal Anisotropic Nanostructures on Titanium Fabricated by Maskless Dry Etching

“…20,21,23,24 However, studies on such nanotopographies on titanium, despite its widespread use as biomaterial, are currently scarce, and they often report on only one recipe, provide few details of the fabrication process, and focus almost exclusively on antibacterial activity and biocompatibility. 20,21,24,25 Table S1 compiles a list of patterned etching studies of titanium, performed using various gases. Studies of chlorine-based maskless etching of titanium and further exploration for biomedical and other applications are listed in Table S2.…”

“…Therefore, a low-cost and high-fidelity fabrication method for generating nanostructures on titanium is highly desirable, and plasma etching is a possible answer to this problem. RIE has been shown to be capable of generating erect arrays of vertical nanopillars, similar to those found on the wings of cicadas and dragonflies, and NSSs spanning several cm 2 can be produced rapidly. ,,, However, studies on such nanotopographies on titanium, despite its widespread use as biomaterial, are currently scarce, and they often report on only one recipe, provide few details of the fabrication process, and focus almost exclusively on antibacterial activity and biocompatibility. ,,, Table S1 compiles a list of patterned etching studies of titanium, performed using various gases. Studies of chlorine-based maskless etching of titanium and further exploration for biomedical and other applications are listed in Table S2.…”

Generation of Ultralong Liposome Tubes by Membrane Fusion beneath a Laser-Induced Microbubble on Gold Surfaces

“… 17 − 19 Our home-made optical tweezers were used to focus a laser onto the sample. 20 − 22 The sample was irradiated with continuous wave laser light (λ = 808 nm) through an objective lens to resonantly excite gap-mode localized surface plasmons.…”

“…These contain a fluorescent dye (rhodamine B), and the average size ( d ) was evaluated to be 150 nm. An aqueous solution containing the liposomes was brought into contact with a plasmonic nanostructure comprising a gold nanopyramidal dimer array on a glass cell. − Our home-made optical tweezers were used to focus a laser onto the sample. − The sample was irradiated with continuous wave laser light (λ = 808 nm) through an objective lens to resonantly excite gap-mode localized surface plasmons.…”

Numerical Simulations of Double-Well Optical Potentials in All-Dielectric Nanostructures for Manipulation of Small Nanoparticles in Aqueous Media

“…Attempts to overcome the latter drawback involve strongly enhanced and localized plasmonic fields in nanostructured metallic surfaces. − These plasmonic fields are electromagnetic hotspots tightly confined to the nanometer-scale subdiffraction regions and excited through resonant coupling of light to charge density oscillations at metal surfaces . Using plasmonic fields is also limited because the intrinsic Joule heating of metals induces unstable trapping due to thermophoresis and fluid convection, and may cause conformational changes in biomolecules. ,,, …”