From GaudiLabs (http://www.gaudi.ch/GaudiLabs/) a very interesting project of low cost laser tweezer (optical trap).
“Optical Tweezers are scientific instruments to manipulate objects of microscopic size. These can be small plastic beads or biological material like cells. The trapping is achieved by focusing a laser beam on the dielectric particles that are then attracted to the region of strongest electric field, which is the center of the beam. The fact that samples under a microscope can be manipulated gives new possibilities to explore. The force applied on the object depends linearly on its displacement from the trap center just as with a simple spring system. Micro-beads can thus be used as handles and forces can be determined though the interaction.“
“The main component of an optical tweezer are a microscope to see the sample, a laser beam focused on the sample to manipulate, special filter and lenses and a movable stage. The sum of this equipment as used in regular laboratories are usually big and quite expensive.”
To reduce the cost, the Gaudilabs team turned to recycling, using parts from DVD drive and used an Arduino board to control the device.
A video of the working instrument may be downloaded at https://youtu.be/BT6NgV5XQqQ
The original article on which the project was based is:
Kasukurti A., Potcoava M., Desai S. A., Eggleton C., Marr D. W. M., “Single-cell isolation using a DVD optical pickup,” Opt. Express 19(11), 10377–10386 (2011).10.1364/OE.19.010377