# US 9,435,722 B2 · Filtering particles from blood or other media > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,722 B2 - Document ID: US9435722B2 - Status: Granted - Kind: B2 - Application number: 14/353,512 - Filed: 2012-10-24 - Published: 2014-10-09 - Granted: 2016-09-06 - Earliest claimed: 2011-10-25 - Assignees: Koninklijke Philips N.V. - Applicants: Koninklijke Philips N.V. - Inventors: Reinhold Wimberger-Friedl; Anja Van De Stolpe; Freek Van Hemert - Web page: https://patentgrep.com/patent/US9435722B2 ## CPC - G01N 1/4077: {by other techniques involving separation of suspended solids} - G01N 33/54326: {Magnetic particles} - G01N 33/5759: {involving compounds localised on the membrane of tumour or cancer cells} - G01N 2001/4088: {filtration} - Y10T 436/25375: Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.] - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A filter element and method for retaining particles of a medium, for example rare cells of blood. The filter element includes at least one opening that has an elongate cross section and/or a cross section that decreases in a flow direction. The filter element may be bordered by a transparent wall. The filter element may be provided with a plurality of elongate openings of a stepwise decreasing cross section that are arranged on a common transparent slide. The filter element permits high flow rates to be realized throughout the filtering process and the retained particles are immediately ready for visual inspection without a need for a further transfer. ## Claims ### Claim 1 A filter element for retaining components of a medium flowing in a flow direction through at least one opening, wherein said opening is a bottleneck in a flow path of the medium wherein the flow path is wider in front and behind the bottleneck; has an elongate cross section, measured perpendicular to the flow direction, that decreases along an extended length of the opening in the flow direction; and is bordered by a transparent wall. ### Claim 2 (depends on 1) The filter element according to claim 1, wherein said opening has an elongate cross section with a ratio between a maximal diameter and a minimal diameter of said cross section being larger than 2:1. ### Claim 3 (depends on 1) The filter element according to claim 1, wherein said opening has a cross section with a minimal diameter that decreases in flow direction by more than about 20%. ### Claim 4 (depends on 1) The filter element according to claim 1, wherein at least two openings are arranged in parallel. ### Claim 5 (depends on 1) The filter element according to claim 1, wherein minimal diameter of the cross section of the opening decreases in at least one step. ### Claim 6 (depends on 1) The filter element according to claim 1, wherein at least one valve is provided for selectively forwarding the medium leaving the opening to different destinations. ### Claim 7 (depends on 1) The filter element according to claim 1, wherein a fluidic system is provided for supplying reagents to the filter element that mix with the medium and/or that are needed for a further processing of retained particles. ### Claim 8 (depends on 1) A filter system comprising a filter element according to claim 1, an objective lens and/or an image sensor is provided adjacent to the opening of the filter element. ### Claim 9 (depends on 1) A filter system comprising a filter element according to claim 1, wherein a magnet is provided for actuating magnetic particles of the medium in the filter element. ### Claim 10 (depends on 9) The filter system of claim 9, wherein a magnet is used for attracting magnetic particles of the medium at least transiently to a wall of the opening. ### Claim 11 (depends on 1) The filter element according to claim 1, wherein the opening or a part thereof, or a part within associated flow channels, or at least one magnetic particle of the medium comprises specific binding sites for components of the medium. ### Claim 12 (depends on 1) A method for filtering a medium in a filter element according to claim 1, wherein: a) the medium is passed in a flow direction through the at least one opening such that particles of the medium are retained in said opening, wherein said opening is a bottleneck in a flow path of the medium wherein the flow path is wider in front and behind the bottleneck, said opening having an elongate cross section, measured perpendicular to the flow direction, that decreases along an extended length of the opening in the flow direction; b) a preparation medium is passed through the at least one opening for treating the retained particles; c) treated particles are imaged and/or moved into a separate compartment for further analysis. ### Claim 13 (depends on 1) A method for cell-based diagnostics and/or for the isolation of cells comprising the steps of filtering a medium by using the filter element according to claim 1; and performing at least one diagnostic procedure on cells from the medium that are retained on the filter element and/or isolating the cells from the medium that are retained on the filter element. ### Claim 14 A method for filtering particles out of a medium by retaining them in at least one opening through which said medium passes in a flow direction, wherein said opening is a bottleneck in a flow path of the medium in which the flow path is wider in front and behind the bottleneck, said opening having an elongate cross section, measured perpendicular to the flow direction, that decreases along an extended length of the opening in the flow direction; wherein the particles are retained at different positions in the flow direction which correspond to a property of said particles. ### Claim 15 (depends on 14) The method according to claim 14, wherein said at least one opening is optically inspected from a direction substantially perpendicular to the flow direction of the medium.