Lawrence R Erickson

US Patent:

20130144538, Jun 6, 2013

Filed:

Dec 6, 2012

Appl. No.:

13/706453

Inventors:

Lawrence Erickson - Brooklyn Park MN, US
Trevor Huang - Maple Grove MN, US
Tessy Kanayinkal - Brooklyn Park MN, US
Craig Petersen - Brooklyn Park MN, US
Charlene Yuan - Woodbury MN, US

Assignee:

MEDTRONIC, INC. - Minneapolis MN

International Classification:

G01N 33/49

US Classification:

702 19

Abstract:

Activated clotting time (ACT) tests detect blood clotting time based on the viscosity changes of a test sample, using a ferromagnetic washer lifted to the top of a test chamber and then dropped from the top via gravity; a drop time greater than a preset threshold value indicates clotting of the test sample. Blood samples which have high levels of heparin usually produce very weak clots that may easily be destroyed by the lifting movement of the washer. But if the clot threshold is set low to detect the weak clots, false detections occur during early testing cycles when activators are not fully suspended during the mixing cycle. Improved algorithms for lifting the washer and adjusting over time enable accurate detection of weak clots.

US Patent:

D2447908, Jun 21, 1977

Filed:

Sep 16, 1975

Appl. No.:

5/613968

Inventors:

Phillip H. Carlson - Minneapolis MN
Lawrence E. Erickson - Edina MN

Assignee:

International Telephone and Telegraph Corporation - New York NY

International Classification:

D2102

US Classification:

D34 5BC

US Patent:

20160238621, Aug 18, 2016

Filed:

Apr 21, 2016

Appl. No.:

15/135327

Inventors:

- Minneapolis MN, US
Lawrence Erickson - Brooklyn Park MN, US
Trevor Huang - Maple Grove MN, US
Tessy Kanayinkal - Brooklyn Park MN, US
Craig Petersen - Brooklyn Park MN, US
Charlene Yuan - Woodbury MN, US

International Classification:

G01N 33/86

Abstract:

Activated clotting time (ACT) tests detect blood clotting time based on the viscosity changes of a test sample, using a ferromagnetic washer lifted to the top of a test chamber and then dropped from the top via gravity; a drop time greater than a preset threshold value indicates clotting of the test sample. Blood samples which have high levels of heparin usually produce very weak clots that may easily be destroyed by the lifting movement of the washer. But if the clot threshold is set low to detect the weak clots, false detections occur during early testing cycles when activators are not fully suspended during the mixing cycle. Improved algorithms for lifting the washer and adjusting over time enable accurate detection of weak clots.