Abstract: Methods and apparatus for analyzing surface properties of particles are provided. A method for analyzing the surface properties of the particle includes a associating a first particle with a first capture zone having a specific binding affinity for a first chemical species, applying an optical force to the first particle, sensing a response of the first particle to the optical force, and using the sensed response to determine the presence, absence or quantity of the first chemical species on the first particle surface. This process may be repeated in parallel to test multiple particles. In addition to directly testing the surface properties of the particles, the method can be used in direct, indirect and competitive assays to determine the presence, absence or quantity of free or immobilized analytes. A fluidic cartridge with capture zones having avidities that are tuned for the use of optical forces is provided. A software routine for performing the method is also provided.

Abstract: Methods and apparatus for analyzing surface properties of particles are provided. A method for analyzing the surface properties of the particle includes a associating a first particle with a first capture zone having a specific binding affinity for a first chemical species, applying an optical force to the first particle, sensing a response of the first particle to the optical force, and using the sensed response to determine the presence, absence or quantity of the first chemical species on the first particle surface. This process may be repeated in parallel to test multiple particles. In addition to directly testing the surface properties of the particles, the method can be used in direct, indirect and competitive assays to determine the presence, absence or quantity of free or immobilized analytes. A fluidic cartridge with capture zones having avidities that are tuned for the use of optical forces is provided. A software routine for performing the method is also provided.

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.