Serial Raman spectroscopy of particles trapped on a waveguide

Løvhaugen, Pål; Ahluwalia, Balpreet Singh; Huser, Thomas; Hellesø, Olav Gaute

doi:10.1364/oe.21.002964

Cited by 23 publications

(19 citation statements)

References 16 publications

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“…The radiation pressure continuously push the particles forward. Raman-spectroscopy has been used to characterize particles propelled along a waveguide [9]. Lifting the particles up would avoid recording the Raman-spectra of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Optical transport, lifting and trapping of micro-particles by planar waveguides

Helle¹,

Ahluwalia²,

Hellesø³

2015

Opt. Express

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Optical waveguides can be used to trap and transport microparticles. The particles are held close to the waveguide surface by the evanescent field and propelled forward. We propose a new technique to lift and trap particles above the surface of the waveguides. This is made possible by a gap between two opposing, planar waveguides. The field emitted from each of the waveguide ends diverge fast, away from the substrate and into the cover-medium. By combining two fields propagating at an angle upwards and coming from opposite sides of a gap, particles can be stably lifted and trapped at the crossing of the two fields. Thus, particles are transported by waveguides leading to a gap, where they are lifted away from the substrate and trapped. The experiments are supported by numerical simulations of the forces on the micro-particles. Fluorescence imaging is used to track the particles in 3D with a precision of 50 nm.

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Section: Introductionmentioning

confidence: 99%

Optical transport, lifting and trapping of micro-particles by planar waveguides

Helle¹,

Ahluwalia²,

Hellesø³

2015

Opt. Express

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“…[1][2][3][4][5][6][7][8][9][10][11][12] Optical waveguides have an evanescent field that stretches about 250 nm from their surfaces. They are thus attractive devices for on-chip manipulation, detection and sorting of particles.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the particles are pulled down to the waveguide surface and propelled forward by the strong gradient and radiation forces, respectively. 8 In order to have a lab-on-chip system, it is advantageous if on-chip methods can also be used to detect and characterize the trapped particles. 1 In addition to propulsion of various types of particles, several optical functions have been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

On-chip phase measurement for microparticles trapped on a waveguide

Dullo

Hellesø

2015

Lab Chip

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Polystyrene microparticles are trapped on a waveguide Young interferometer and the phase change caused by the trapped particles is measured. This is a novel, on-chip method that can be used to count and characterize trapped particles. The trapping of single particles is clearly identified. Simulations show that the phase change increases with the diameter up to 7 μm, while for larger particles, morphology-dependent resonances appear. For 7 μm particles, a phase change of -0.13 rad is measured, while the simulated value is -0.28 rad. Extensive simulations are carried out regarding the phase change, waveguide transmission and the forces on the particles, and also regarding sources of the discrepancy between simulations and measurements.

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“…Dual-beam optical traps have recently been further developed [13][14][15][16]. High quality fibrebased traps have been demonstrated, applying fibres solely for trapping [13], and for trapping, Raman excitation and signal collection [14].…”

Section: Introductionmentioning

confidence: 99%

“…However, in view of the delicate mounting of the fibres, this approach does not permit widespread use. The trap reported in [15,16] is based on microfabricated Ta 2 O 5 waveguides. Although this is a very important step forward in view of the fabrication procedure, the research material Ta 2 O 5 is not likely to give rise to a general waveguiding platform for sensing.…”

Section: Introductionmentioning

confidence: 99%

On-chip optical trapping and Raman spectroscopy using a TripleX dual-waveguide trap

Boerkamp¹,

Leest²,

Heldens³

et al. 2014

Opt. Express

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We present a new approach to the dual-beam geometry for onchip optical trapping and Raman spectroscopy, using waveguides microfabricated in TripleX technology. Such waveguides are box shaped and consist of SiO 2 and Si 3 N 4 , so as to provide a low index contrast with respect to the SiO 2 claddings and low loss, while retaining the advantages of Si 3 N 4 . The waveguides enable both the trapping and Raman functionality with the same dual beams. Polystyrene beads of 1 µm diameter can be easily trapped with the device. In the axial direction discrete trapping positions occur, owing to the intensity pattern of the interfering beams. Trapping events are interpreted on the basis of simulated optical fields and calculated optical forces. The average transverse trap stiffness is 0.8 pN/nm/W, indicating that a strong trap is formed by the beams emitted by the waveguides. Finally, we measure Raman spectra of trapped beads for short integration times (down to 0.25 s), which is very promising for Raman spectroscopy of microbiological cells.

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Serial Raman spectroscopy of particles trapped on a waveguide

Cited by 23 publications

References 16 publications

Optical transport, lifting and trapping of micro-particles by planar waveguides

Optical transport, lifting and trapping of micro-particles by planar waveguides

On-chip phase measurement for microparticles trapped on a waveguide

On-chip optical trapping and Raman spectroscopy using a TripleX dual-waveguide trap

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