I presented one slide and a 3 minute video as a case-study during the keynote presentation at Helsinki NIDays 2009 this morning.
Here a DNA-molecule is being stretched between two optically trapped polystyrene micron-sized beads. We're using an FPGA-based real-time controller for steering the upper trap. It's programmed with a PI-loop which aims to keep the force acting on the lower bead constant. Around 10s into the video we switch on the feedback-loop and we see the [...]
A ~48 000 base-pair long (ca 16 um) piece of DNA is stretched between two optically trapped ca 2 um diameter polystyrene beads. Bright-field real-time view through a 100x microscope. Scale-bar in microns on the right.
Tuesday, January 27, 2009
Were stretching a 13 kb DNA-construct between two optically trapped beads. This isn't a video of the experiment itself, but of some entangled beads we found in an old sample. The beads are 3 or 2 micron in diameter, and we hold on to the middle big bead with the optical trap while moving around [...]
Tuesday, October 28, 2008
Life is simple at Reynolds numbers much below 0.1 Four 200 x 50 um inlet channels join into one 800 x 50 um main channel. The blue and clear liquids mix only by diffusion. See also here.
Monday, September 29, 2008
We got a new Ocean Optics spectrometer to the lab today and naturally I had to play around with it a bit in the evening. Compared to our 20+ year old Jobin Yvon rotating-grating thing this one is a very small tidy box, with data transmission and power over USB, and an SMA-connector for light [...]
Sunday, September 21, 2008
I'm fitting some more equipment around a Nikon TE-2000 microscope, and the stock objective turret is in the way. Machined this objective holder in steel yesterday.
I follow a number of scientific journals through their RSS feed of new articles. Google-reader makes it easy to stay on top of the 20 or so most interesting journals that each publish maybe 10 papers per week. But now AIP and their website provider Scitation are messing it all up. They've decided to expand [...]
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In an attempt to image the acoustic fields emerging from ultrasound transducers we've built a small Schlieren setup with stroboscopic LED illumination. There's a 10-cycle 7.5 MHz sound-wave coming in from the top at a velocity of around 1500 m/s, and if you illuminate it at just the right time with a 500 ns pulse [...]
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