Method and apparatus for magnetically separating biological particles from a mixture

A system for collecting a selected quantity of biological particles from a fluid medium, said system comprising

• tag means for dispersing in the fluid medium and comprising a magnetically responsive material having at least one substance immobilized upon an exterior surface for coupling to said biological particles,
• magnetic field source means for generating within said fluid medium a magnetic field to establish a flow of biological particles coupled to said tag means toward said magnetic field source,
• plate means having a surface positioned within said flow of biological particles for collecting said particles thereon,
• means for measuring a parameter responsive to the collection of particles against said surface wherein the value of said parameter changes according to the quantity of particles collected thereon, and
• transfer means for removing said particles collected against said surface from said fluid medium, for transfer to an optical element, in response to a selected change in the value of said measured parameter.

A method for collecting biological particles from a fluid medium for image analysis, comprising the steps of

• providing tag means comprising a magnetically responsive material having at least one substance immobilized upon an exterior surface for coupling to said biological particles, said tag means being dispersed within said fluid medium,
• applying a magnetic field to said fluid medium to establish a flow of biological particles coupled to said tag means,
• disposing plate means having a surface positioned within said flow of biological particles to collect said particles thereon, and
• transferring said particles from said surface to a receiver element with a spatial distribution of particles substantially similar to the distribution of said particles collected on said surface.

A method for collecting a selected quantity of biological particles from a fluid medium, comprising the steps of

• providing tag means comprising a magnetically responsive material having at least one substance immobilized upon an exterior surface for coupling to said biological particles, said tag means being dispersed within said fluid medium,
• applying g magnetic field to said fluid medium to establish a flow of biological particles coupled to said tag means,
• disposing plate means having a surface positioned within said flow of biological particles to collect said particles thereon,
• measuring a parameter responsive to the collection of particles against said surface, wherein the value of said parameter changes according to the quantity of particles collected thereon,
• withdrawing said plate means with said biological particles collected thereon from the fluid medium in response to a selected change in the value of said measured parameter, and
• transferring said particles collected on said surface to an optical element for image analysis.

A system for collecting, for image analysis, biological particles from a fluid medium, said system comprising

• tag means for dispersing in the fluid medium and comprising magnetically responsive material having a selectable magnetic state and having at least one substance immobilized upon an exterior surface with specific affinity for an epitope on said biological particles,
• magnetic field source means for generating within said fluid medium a magnetic field to select said magnetic state of said tag elements coupled to said biological particles, and for establishing a flow of biological particles within said fluid medium,
• plate means having a surface for positioning within said flow for collecting biological particles thereon, and
• transfer means, coupled to said plate means, for removing said surface with said collected biological particles from said fluid medium.