| CPC B01L 3/502715 (2013.01) [B01L 3/502776 (2013.01); G01N 15/1459 (2013.01); G01N 33/54366 (2013.01); B01L 2200/0636 (2013.01); B01L 2200/0647 (2013.01); B82Y 35/00 (2013.01); G01N 2015/1006 (2013.01); G01N 2015/1493 (2013.01)] | 18 Claims |

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1. A method for determining the size of a biological nanoparticle in a fluid sample, the method comprising:
providing a planar microfluidic chip comprising at least one microfluidic channel, wherein the at least one microfluidic channel comprises at least one constriction comprising a detection region;
introducing the fluid sample into the planar microfluidic chip, the fluid sample comprising a plurality of biological nanoparticles;
flowing a portion of the plurality of biological nanoparticles through the at least one microfluidic channel;
illuminating in the detection region of the at least one microfluidic channel at least one biological nanoparticle from the portion of the plurality of biological nanoparticles on a particle-by-particle basis, wherein the illuminating of the at least one biological nanoparticle comprises using an illumination source having a beam width of less than 2 μm within the at least one microfluidic channel, and wherein the illumination source illuminates the detection region within the at least one microfluidic channel comprising a cross sectional area of less than 10 μm2;
detecting epifluorescent light intensity emitted from the at least one biological nanoparticle; and
assigning a size value to the at least one illuminated biological nanoparticle based on the detected epifluorescent light intensity, wherein a biological nanoparticle with a larger hydrodynamic radius emits a higher intensity of light compared to a biological nanoparticle with a smaller hydrodynamic radius, and wherein the biological nanoparticle has a hydrodynamic diameter of less than 1 μm.
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