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Meistverkauft in Ingenieurwissenschaften
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- KurzbeschreibungOptical trapping and manipulation by laser beams offers the unique possibility to handle<br>single micrometer-sized particles such as living cells without any mechanical contact,<br>damage or contamination. A second hot topic in biology is microfluidics, where the examination<br>of biological samples in channel structures with widths below 100 µm reduces<br>the used sample volume significantly. While the combination of both techniques results in<br>attractive lab-on-a-chip structures for particle sorting and analysis, the commonly bulky<br>trapping setup is contradictory to the miniaturized concept. Here, the use of vertical-cavity<br>surface-emitting lasers (VCSELs) as light sources in optical trapping systems allows a strong<br>reduction of the setup complexity owing to the small dimensions, low cost and high beam<br>quality of these devices.<br>This thesis gives a detailed study on optical manipulation systems based on vertically<br>emitting laser diodes. A standard optical tweezers setup as well as a novel, miniaturized<br>system, the so-called integrated optical trap are investigated. The latter aims for particle<br>separation and sorting in microfluidics resulting in low-cost, portable modules.<br>A classical optical tweezers system based on a high numerical aperture objective in combination<br>with a VCSEL light source is investigated. Standard multi-mode as well as single-mode<br>surface relief VCSELs are used as laser source. With both kinds of VCSELs, optical trapping<br>of polystyrene particles of sizes ranging from 4 to 15µm is demonstrated with some<br>milliwatts of optical power at the sample stage. A maximum trapping force of 4.4 pN for<br>15 µm particles is achieved with the multi-mode laser, proving the suitability of multi-mode<br>lasers for optical manipulation despite their inferior beam profile.<br>By using two-dimensional VCSEL arrays instead of solitary lasers, the system is extended<br>to a multiple optical tweezers setup in a straightforward manner. To avoid any additional<br>optics, densely packed VCSEL arrangements with a device spacing of less than 25 µm are<br>used, where a novel fabrication process allows the seamless integration of the inverted surface<br>relief technique for enhanced beam quality. By electrical switching between individual<br>devices of the array, non-mechanical particle translation with velocities of up to 12 µm/s is<br>achieved. With a tilted linear VCSEL array, an optical lattice is generated in the optical<br>tweezers setup, and continuous deflection of particles is realized
- AutorAndrea Kroner
- Ausgabe1. Auflage
- VerlagCuvillier Verlag
- Seiten164 Seiten
- Gewicht220 g
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