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US006752961B2
(12) United States Patent ao) Patent No.: us 6,752,961 B2
Kopf-Sill et al. (45) Date of Patent: Jun. 22,2004
(54) MODIFIED SIPHONS FOR IMPROVING METERING PRECISION
(75) Inventors: Anne R. Kopf-Sill, Portola Valley, CA (US); Carol T. Schembri, San Mateo, CA (US)
(73) Assignee: Abaxis, Inc., Union City, CA (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) bydays.days.
(21) Appl. No.: 09/834,300
(22) Filed: Apr. 12, 2001
(65) Prior Publication Data
US 2003/0207457 Al Nov. 6, 2003
Related U.S. Application Data
(63) Continuation of application No. 08/562,327, filed on Nov. 22, 1995, now Pat. No. 6,235,531, which is a continuation of application No. 08/254,406, filed on Jun. 6, 1994, now abandoned, which is a continuation-in-part of application No. 08/115,162, filed on Sep. 1, 1993, now Pat. No. 5,591, 643.
(51) Int. C I. G01N 9/30
(52) U.S. CI 422/72; 422/100; 422/102;
436/45; 436/180
(58) Field of Search 422/72, 100, 102;
436/45, 180
(56) References Cited
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OTHER PUBLICATIONS
Tech Update, "Blood Rotor Test Magic," Popular Mechanics, Feb. 1993.
Schembri, C. Abstract, "Centrifligation and Capillary Inte-
grated into a Multiple Analyte Whole Blood Analyzer,"
Abaxis, Inc., Feb. 1993.
Marketing Brochure, Abaxis, Inc., Aug. 1993.
* cited by examiner
Primary Examiner—-Jan M. Ludlow
(74) Attorney, Agent, or Firm—Gray, Cary, Ware & Freidenrich LLP
(57) ABSTRACT
The present invention provides centrifugal rotors for delivering a premeasured volume of liquid to a chamber in the rotor. In particular the rotors comprise siphons for delivering a premeasured volume of liquid between a first and a second chamber in the rotor. The siphons of the invention are designed such that the inlet of the siphon on the first chamber is radially outward of the siphon outlet on the second chamber. The first chamber is emptied to a level equivalent to the radial position of the siphon outlet.
6 Claims, 6 Drawing Sheets
