Method for determining the size of nanoparticles in a colloid

Abstract

The system includes an adjustable light source constructed to direct a beam of electromagnetic radiation at a specimen chamber that allows a portion of the beam to scatter when illuminating particles within the chamber. The scattered portion of the beam is directed to a sensor, the sensor having a frame rate and a time period between frames. The system may have a processor connected to the sensor and light source, the processor may perform the following steps: activate the light source and obtain images from sensor; if the images from the sensor show that particles are blinking then reduce the frame rate, set the exposure time to at least 60% of the time between frames and reduce the illumination. Then the processor obtains additional images and processes those images to mitigate blurring. The processor determines the Brownian motion of the particles from the processed images and determines the sizes of the particles based on the motion.

1 . A method for determining the size of particles for use in a system that comprises a light source constructed to direct a beam of electromagnetic radiation at a specimen chamber that allows a portion of the beam to scatter when illuminating particles within the chamber, wherein the scattered portion is directed to a sensor the sensor having an image plane, the system further comprises electrodes constructed to produce an electric field within the image plane and across in the specimen chamber, the method comprising:
 A. activating the light source;   B. obtaining images from sensor while actuating the electrodes to produce the electric field;   C. determining the Brownian motion of the particles from the images of step (B);   D. decomposing the motion into a first component that is substantially parallel to the electric field and a second component that is substantially orthogonal to the electric field;   E. for each component, determining the sizes of the particles.   
     
     
         2 . The method of  claim 1 , further comprising:
 prior to step (B):
 (1) obtaining images from sensor; 
 (2) determining the Brownian motion of the particles from the images; 
 (3) determining the sizes of the particles based on the Brownian motion; 
 (4) determining a particle size distribution (PSD) function based on the determined sizes; 
 (5) from the PSD determining whether the particles are elongated; 
 (6) if the particles are elongated, continue to steps (B)-(E). 
   
     
     
         3 . A system for determining the particle size distribution of a colloid, the system comprising:
 A light source constructed to direct a beam of electromagnetic radiation at a specimen chamber, the chamber constructed to allow a portion of the beam to scatter when illuminating particles within the chamber;   a sensor position to detect the scatter of the beam, the sensor having an image plane;   electrodes constructed to produce an electric field within the image plane and across the specimen chamber;   a processor connected to the light source, sensor and electrodes; the processor configured to perform the following steps:
 A. activating the light source; 
 B. obtaining images from sensor while actuating the electrodes to produce the electric field; 
 C. determining the Brownian motion of the particles from the images of step (B); 
 D. decomposing the motion into a first component that is substantially parallel to the electric field and a second component that is substantially orthogonal to the electric field; 
 E. for each component, determining the sizes of the particles. 
   
     
     
         4 . The system of  claim 3 , wherein the processor performs the following steps before step (B):
 (1) obtaining images from sensor;   (2) determining the Brownian motion of the particles from the images;   (3) determining the sizes of the particles based on the Brownian motion;   (4) determining a particle size distribution (PSD) function based on the determined sizes;   (5) from the PSD determining whether the particles are elongated;   (6) if the particles are elongated, continue to steps (B)-(E).