Difference between detection and tracking of nanoparticles

<p>Detecting a nanoparticle means knowing whether it is present or not. This is a point (in time) measurement and yields a binary result. For instance, a <a class="wikilink" href="/flow_cytometer/">flow cytometer</a> registers a signal that crosses a threshold if a particle is in the observation area (see: <a class="wikilink" href="/effects_of_swarm_of_particles_in_flow_cytometers/">Effects of swarm of particles in flow cytometers</a>). This can be extended if one looks at the intensity of the signal and tries to extract more information, such as the particle size (or mass). </p> <p>Tracking, on the other hand, implies connecting several time-point measurements. It means knowing the position of <em>the same particle</em> at different time-stamps. This is what the NTA technique uses (see: <a class="wikilink" href="/nanoparticle_tracking_analysis/">nanoparticle tracking analysis</a>). In order for the tracking to be able to provide information on the particles, the time resolution should be higher than the characteristic diffusion or advection<sup id="fnref:1"><a class="footnote-ref" href="#fn:1">1</a></sup> time. </p> <p>References: [<a class="litnote tooltip" href="/literature/@Faez2015">@Faez2015<span class="tooltiptext">Fast, Label-Free Tracking of Single Viruses and Weakly Scattering Nanoparticles in a Nanofluidic Optical Fiber</span></a>]</p> <p>See further: <a class="wikilink" href="/limitations_of_nanoparticle_tracking_analysis/">limitations of nanoparticle tracking analysis</a></p> <div class="footnote"> <hr /> <ol> <li id="fn:1"> <p>Advection is the transport of a substance or quantity by bulk motion. <a href="https://en.wikipedia.org/wiki/Advection">Wikipedia</a>&#160;<a class="footnote-backref" href="#fnref:1" title="Jump back to footnote 1 in the text">&#8617;</a></p> </li> </ol> </div>