Automated extraction and purification of samples using optical tweezers

Abstract

An apparatus and method for purifying a forensic sample using an automated extraction and purification system includes optical tweezers; an input channel through which the sample is introduced; a chamber which receives the sample from the input channel; a collection channel through which selected particles of the sample are removed; and an output through which unselected particles of the sample are removed. At least one buffer input channel is provided. The input channel may allow sedimentation of the sample into the chamber by gravity. In another arrangement, the system includes an optical trapping system; a first channel through which the sample is introduced; a second channel through which buffer is introduced; wherein the optical tweezers are used to move selected particles of the sample from the first channel to the second channel. The selected particles may be sperm. The optical tweezers preferably utilize holographic optical trapping.

1 . A method of purifying a forensic sample in an automated extraction and purification system which uses optical tweezers, comprising:
 introducing the forensic sample along with a fluid, into an input channel;   flowing the sample through said input channel into a chamber;   using the optical tweezers to separate selected particles of the sample in the chamber;   removing the separated selected particles through a collection channel; and   removing the unselected particles through an output.   
     
     
         2 . The method according to  claim 1 , wherein the fluid is a buffer. 
     
     
         3 . The method according to  claim 2 , wherein the input channel is primed first with said buffer. 
     
     
         4 . The method according to  claim 2 , wherein the buffer is introduced in a separate input channel. 
     
     
         5 . The method according to  claim 2 , where the sample is rehydrated with buffer prior to introducing the sample into the input channel. 
     
     
         6 . The method according to  claim 1 , wherein the sample is sedimented to the bottom of the chamber by gravity. 
     
     
         7 . The method according to  claim 1 , wherein the fluid is pumped through the chamber. 
     
     
         8 . The method according to  claim 1 , wherein the chamber incorporates a window for imaging by a machine vision system. 
     
     
         9 . The method according to  claim 8 , further comprising: scanning the chamber for the selected particles of the sample. 
     
     
         10 . The method according to  claim 9 , further comprising: identifying the selected particles by image processing using the machine vision system. 
     
     
         11 . The method according to  claim 10 , wherein the sperm are lifted above the surface and are manipulated in three dimensions. 
     
     
         12 . The method according to  claim 10 , wherein the selected particles are collected in a separate and sealed container. 
     
     
         13 . The method according to  claim 12 , wherein the container is removed via a sterile snap-off connection. 
     
     
         14 . The method according to  claim 1 , further comprising: removing the unselected particles using optical tweezers through the output. 
     
     
         15 . The method according to  claim 1 , further comprising: providing a purging flow to remove the unselected particles through the output. 
     
     
         16 . The method according to  claim 1 , further comprising: cleaning the chamber using a purging flow. 
     
     
         17 . The method according to  claim 10 , wherein imaging of the particles using the machine vision system, is automated, and a visual record can be maintained. 
     
     
         18 . The method according to  claim 1 , wherein the optical tweezers utilize holographic optical trapping. 
     
     
         19 . The method according to  claim 1 , wherein the optical tweezers utilize non-holographic optical trapping. 
     
     
         20 . The method according to  claim 17 , wherein a report is automatically generated to provide information on the selected particles. 
     
     
         21 . The method according to  claim 19 , wherein non-diffraction limited optical traps generated by the optical trapping system, may be used to tweeze only the selected particles. 
     
     
         22 . The method according to  claim 1 , wherein optical tweezers are white light optical tweezers. 
     
     
         23 . The method according to  claim 18 , wherein a holographic optical trapping system is used with a stage for mounting of its components, and the stage is movable. 
     
     
         24 . The method according to  claim 23 , wherein optical traps generated by the holographic optical trapping system, are blinked to lose the unselected particles. 
     
     
         25 . The method according to  claim 1 , wherein the sample includes a plurality of biological cells and at least one biological cell is killed by one of ultraviolet light and a chemical addition to the sample. 
     
     
         26 . The method according to  claim 1 , further comprising: coating walls of the input channel, the chamber, the collection channel, and the output, to prevent sticking. 
     
     
         27 . The method according to  claim 1 , wherein a flow through the system is one of static, dynamic, and batch flow. 
     
     
         28 . The method according to  claim 1 , wherein separation of the sample into selected particles and unselected particles is performed using flow switching. 
     
     
         29 . The method of  claim 18 , wherein lasers of the holographic optical trapping system can be used as particle probes. 
     
     
         30 . The method according to  claim 1 , wherein the selected particles are at least one of sperm and epithelial cells. 
     
     
         31 . The method according to  claim 1 , wherein said output comprises a plurality of output channels directed to each of the selected particles. 
     
     
         32 . The method according to  claim 18 , wherein the system is user controlled.