AlgoMantra, b. 2005

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Tuesday, January 22, 2008
microTetris: another glass-bead game from the future

Just so you can appreciate what is going on in the video here, you have glass beads which are one million times smaller than a meter (micro-spheres) which are being manipulated using 'optical tweezers' to play a game of Tetris in a real physical field under a f-ing microscope! I pay homage to thee, powerful geek overlords!

To accomplish microTetris, we use the technique of optical trapping (explained elsewhere on our group's webpage) to hold the glass beads in place. In short, an optical trap is a laser beam which is focused to a very tiny spot (1 micrometer = about 1/1000th of a millimeter) by a strong lens, usually a microscope's objective lens. This focus appears to act as an attractor point, in which small particles like our 1-micrometer glass beads (but also cells or bacteria) can be sucked and from which they cannot escape. This tool, also more figuratively referred to as 'optical tweezers' is nowadays indispensable in biophysical research. It is being used to push cells together to monitor their elastic properties, or to stretch single molecules of DNA until the DNA helix unwinds or breaks, or to measure the forces of the 'motor' that propells bacteria through their surroundings. In fact, we could add a lot more things to this list without being complete.

In our Tetris case, a device called an acousto-optic deflector (AOD) was used to computer-steer the trapping laser light very swiftly across the 42 bead positions as seen in the video—pretty much like the way a monitor steers its electron beam across the pixels on the screen. This was done fast enough for a bead to stay at its location while the laser was scanning the other positions. (At the end of the video, you can observe what happens if we suddenly switch off the laser light: the beads are no longer confined to their traps and can diffuse away easily.)


Now how the hell am I going to make an AOD? Experiments begin soon at 'the lab' under an old microscope, a few laser pointers and .....well, microsound?
Tuesday, January 15, 2008
Morchang - 1

DJ Fadereu with his wife.
Thursday, January 10, 2008
Low Tech Hacking in 2008
You can't know everything all at once, but you can know how to know anything when the opportunity arises. What good is an electronics expert who has never enjoyed Shakespeare? At AlgoMantra, the year 2007 was spent in making software that enabled human-computer interaction in innovative ways.

Towards the tail end of December I did a rather frustrating course on basic interfacing between circuits and computers, but I also realised that the answers I was looking for did not lie in knowing all the fundamentals of electronic engineering. I just wanted to hack cheap Chinese toys and make new stuff, but I think my instructors were trying to teach me the value of patience and perseverance. So if you're in a similar situation, I reccommend the following guide:

for artists and architects

by Usman Haque [] and Adam Somlai-Fischer []

The PDF is a great introduction to circuitbending philosophy, with the only problem that the first chapter mentions something called a CAT, which is actually explained a little later in the document. Who said it was a linear book anyway? I think it's a very useful thing to have lying around though. Also have a look at Doctronics for very clearly explained sensors like the LDR (light-dependant-resistor).

And when you start making your own low-tech sensors and actuators, you might want to contribute to the wiki they've setup. I think that the small PDF is a great idea, but one could have a gigantic repository of this stuff. Most DIY websites just don't explain things clearly to noobs, engaging in the same kind of vainglorious attitude that has allowed the consumer electronics market to become such a fucking pain in the arse.

Thank you, Usman & Adam.