Optimum path: tracking fluorescent nanoparticles using laser

August 30, 2012

(Phys.org)—NIST Center for Nanoscale Science and Technology researchers Gregg Gallatin and Andrew Berglund (now at Quantifind in Palo Alto, CA) have determined the optimum path in which to scan a laser beam in order to track a fluorescing nanoparticle as the particle moves inside a fluid or gas in two or three dimensions. 

The ability to accurately track is extremely useful in biology, in at the nanoscale, and in nanotechnology generally.  In biology, for example, if one or more fluorescing nanoparticles are attached to a protein inside a cell then the position and orientation of that protein can be tracked as it performs its functions inside the cell.  In nanofabrication, many techniques involve nanoparticles or nanostructures coalescing to form useful materials or devices and optimizing these processes requires accurate data on how these nanostructures move.  The path derived by the researchers is considered optimal because it yields the most accurate possible data on the nanoparticle's position as a function of time. 

The researchers developed a simple formula for determining the overall positional accuracy as a function of various standard parameters such as beam intensity and beam size.  The formula for the optimum path was derived using a classical , the calculus of variations, and the resulting solution was verified by showing that it satisfies the conditions of global optimality (i.e. it is the best solution among all possible solutions) using the theory of optimal experimental design.  The positional accuracy was determined using classical statistical methods.  Interestingly, although the path can be smooth in two dimensions, in the beam needs to hop to achieve optimality. 

While the accuracy formula was derived for the most common laser beam shape, a Gaussian, the researchers are expanding the work to show how changing the laser beam's shape can further improve the tracking accuracy.

Explore further: Scientists shed light on molecules in living cells

More information: Optimal laser scan path for localizing a fluorescent particle in two or three dimensions, G. M. Gallatin and A. J. Berglund, Optics Express 20, 16381–16393 (2012). www.opticsinfobase.org/abstract.cfm?uri=oe-20-15-16381

Related Stories

Scientists shed light on molecules in living cells

August 21, 2007

Clemson University chemists have developed a method to dramatically improve the longevity of fluorescent nanoparticles that may someday help researchers track the motion of a single molecule as it travels through a living ...

Light touch keeps a grip on delicate nanoparticles

May 3, 2012

(Phys.org) -- Using a refined technique for trapping and manipulating nanoparticles, researchers at the National Institute of Standards and Technology (NIST) have extended the trapped particles' useful life more than tenfold. ...

Photonics: Beam me up

May 24, 2012

'Tractor beams' of light that pull objects towards them are no longer science fiction. Haifeng Wang at the A*STAR Data Storage Institute and co-workers have now demonstrated how a tractor beam can in fact be realized on a ...

Researchers track nanoparticle dynamics in three dimensions

August 3, 2012

(Phys.org) -- Researchers from the NIST Center for Nanoscale Science and Technology have used three-dimensional single-particle tracking to measure the dynamic behavior of individual nanoparticles adsorbed at the surface ...

Recommended for you

An engineered surface unsticks sticky water droplets

August 31, 2015

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets ...

Electrical circuit made of gel can repair itself

August 25, 2015

(Phys.org)—Scientists have fabricated a flexible electrical circuit that, when cut into two pieces, can repair itself and fully restore its original conductivity. The circuit is made of a new gel that possesses a combination ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.