Developing a self-calibrating system for volume measurement of spheroidal particles using two acoustically levitated droplets.

Acoustically levitated droplets in the nanoliter to microliter range are studied in various fields. The volume measurements of these are conventionally done using image analysis. A precision-produced calibration sphere is often used to calibrate the recording equipment, which is time-consuming and expensive.

Report on fluorescence lifetime imaging using multiphoton laser scanning microscopy targeting sentinel lymph node diagnostics.

Significance: Sentinel lymph node (SLN) biopsy is an important method for metastasis staging in, e.g., patients with malignant melanoma.

Safe Experimentation in Optical Levitation of Charged Droplets Using Remote Labs.

The work presents an experiment that allows the study of many fundamental physical processes, such as photon pressure, diffraction of light or the motion of charged particles in electrical fields. In this experiment, a focused laser beam pointing upwards levitate liquid droplets. The droplets are levitated by the photon pressure of the focused laser beam which balances the gravitational force.

A microfluidic system in combination with optical tweezers for analyzing rapid and reversible cytological alterations in single cells upon environmental changes.

We report on the development of an experimental platform where epi-fluorescence microscopy and optical tweezers are combined with a microfluidic system to enable the analysis of rapid cytological responses in single cells. The microfluidic system allows two different media to be merged in a Y-shaped channel. Microscale channel dimensions ensure purely laminar flow and, as a result, an environmental gradient can be created between the two media.

A microfluidic system enabling Raman measurements of the oxygenation cycle in single optically trapped red blood cells.

Using a lab-on-a-chip approach we demonstrate the possibility of selecting a single cell with certain properties and following its dynamics after an environmental stimulation in real time using Raman spectroscopy. This is accomplished by combining a micro Raman set-up with optical tweezers and a microfluidic system. The latter gives full control over the media surrounding the cell, and it consists of a pattern of channels and reservoirs defined by electron beam lithography that is moulded into rubber silicon (PDMS).

Optical manipulation in combination with multiphoton microscopy for single-cell studies.

We demonstrate how optical tweezers can be incorporated into a multiphoton microscope to achieve three-dimensional imaging of trapped cells. The optical tweezers, formed by a cw 1064 nm Nd:YVO4 laser, were used to trap live yeast cells in suspension while the 4',6-diamidino-2-phenylindole-stained nucleus was imaged in three dimensions by use of a pulsed femtosecond laser. The trapped cell was moved in the axial direction by changing the position of an external lens, which was used to control the divergence of the trapping laser beam.

Resonance Raman spectroscopy of optically trapped functional erythrocytes.

We introduce a novel setup combining a micro-Raman spectrometer with external optical tweezers, suitable for resonance Raman studies of single functional trapped cells. The system differs from earlier setups in that two separate laser beams used for trapping and Raman excitation are combined in a double-microscope configuration. This has the advantage that the wavelength and power of the trapping and probe beam can be adjusted individually to optimize the functionality of the setup and to enable the recording of resonance Raman profiles from a single trapped cell.

Optical tweezers applied to a microfluidic system.

We will demonstrate how optical tweezers can be combined with a microfluidic system to create a versatile microlaboratory. Cells are moved between reservoirs filled with different media by means of optical tweezers. We show that the cells, on a timescale of a few seconds, can be moved from one reservoir to another without the media being dragged along with them.