Sample interview questions: Can you discuss your knowledge of the principles behind optical tweezers and their uses in biological research?
Sample answer:
Principles of Optical Tweezers
Optical tweezers utilize highly focused laser beams to trap and manipulate microscopic particles by exerting optical forces. These forces arise from the transfer of photon momentum to the particles, which are typically beads or cells.
- Gradient Force: The intensity gradient of the laser beam creates a force that attracts particles towards the region of highest intensity.
- Scattering Force: The scattering of photons off the particles generates a force that opposes the gradient force.
- Refractive Index Mismatch: When the refractive index of the particle differs from the surrounding medium, the laser beam experiences refraction and reflection, resulting in an additional force.
Uses in Biological Research
Optical tweezers enable precise manipulation and interrogation of biological specimens at the micro- and nanoscale, offering unique advantages:
- Non-Invasive Manipulation: Optical tweezers allow for contactless handling of biological samples, preserving their integrity and viability.
- Submicron Precision: The extremely small focal point enables fine-scale manipulation of cells and their components.
- Selective Trapping: The wavelength and polarization o… Read full answer