Methods and apparatus for use of optical forces for identification, characterization and/or sorting of particles

Abstract

Apparatus and methods are provided for interacting light with particles, including but not limited to biological matter such as cells, in unique and highly useful ways. Optophoresis consists of subjecting particles to various optical forces, especially optical gradient forces, and more particularly moving optical gradient forces, so as to obtain useful results. In biology, this technology represents a practical approach to probing the inner workings of a living cell, preferably without any dyes, labels or other markers. In one aspect, a particle may be characterized by determining its optophoretic constant or signature. For example, a diseased cell has a different optophoretic constant from a healthy cell, thereby providing information, or the basis for sorting. In the event of physical sorting, various forces may be used for separation, including fluidic forces, such as through the use of laminar flow, or optical forces, or mechanical forces, such as through adhesion. Various techniques for measuring the dielectric constant of particles are provided.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 09 / 845,245, filed Apr. 27, 2001, entitled “Methods and Apparatus for Use of Optical Forces for Identification, Characterization and / or Sorting of Particles”, and is related to application Ser. No. 09 / 843,902, filed on Apr. 27, 2001, entitled “System and Method for Separating Micro-Particles”, with named inventor Osman Kibar, which claims priority from provisional Application Ser. No. 60 / 248,451, entitled “Method and Apparatus for Sorting Cells or Particles”, filed Nov. 13, 2000. Those applications are incorporated herein by reference as if fully set forth herein.FIELD OF THE INVENTION [0002] This invention relates to methods and apparatus for the selection, identification, characterization, and / or sorting of materials utilizing at least optical or photonic forces. More particularly, the inventions find utility in biological systems, generally considered to be the use of optical forces for int...

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Benefits of technology

[0022] This technology represents a practical approach to probing the inner workings of a particle, such as a living cell, preferably without any dyes, labels or other markers. The “Optophoretic Constant” of a cell uniquely reflects the physiological state of the cell at the exact moment in which it is being analyzed, and permits investigation of the inner workings of cells. These techniques allow simple and efficient gathering of a wide spectrum of information, from screening new drugs, to studying the expression of novel genes, to creating new diagnostic products, and even to monitoring cancer patients. This technology permits the simultaneous analysis and isolation of specific cells based on this unique optophoretic parameter. Stated otherwise, this technology is capable of simultaneously analyzing and isolating specific particles, e.g. cells, based on their differences at the atomic level. Used alone or in combination with modern molecular techniques, the technology provides a useful way to link the intricate mechanisms involving the living cell's overall activity with uniquely identifiable parameters.

[0027] Yet other methods permit the sorting of particles according to their size. One method includes the steps of subjecting the particles to a optical fringe pattern, moving the fringes relative to the particles, wherein the improvement comprises selecting the period of the fringes to have a differential effect on differently sized particles. An allied method sorts or otherwise separates particles based upon the particles flexibility when subject to a optical force. One set of exemplary steps includes: subjecting the particles to an optical pattern having fringes, the fringe spacing being less than the size of the particle in an uncompressed state, moving the fringes relative to the medium containing the particles, and whereby particles having relatively higher flexibility are separated from those with relatively lower flexibility.

[0029] Various techniques are described for enhancing the sensitivity and discrimination of the system. For example, a sensitive arrangement may be provided by separating the particles in a medium having a dielectric constant chosen to enhance the sensitivity of the discrimination between the particles, and changing the medium to one having a dielectric constant which causes faster separation between the particles. One option for enhancing the sensitivity is to choose the dielectric constant of the medium to be close to the dielectric constant of the particles.

[0033] Yet another object of this invention is to provide a system in which particles may be manipulated remotely, thereby reducing the contamination to the system under study.

Problems solved by technology

Existing technologies cannot efficiently and comprehensively address the enormous complexity of this information.

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