The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 21, 1999
Filed:
Apr. 04, 1997
Craig S Chamberlain, Woodbury, MN (US);
Dean E Feyma, Sandstone, MN (US);
Steven J Heilig, St. Paul, MN (US);
Elaine M Yorkgitis, St. Paul, MN (US);
3M Innovative Properties Company, St. Paul, MN (US);
Abstract
A method for measuring the level of stress in a polymeric or pre-polymeric composition within a given volume that includes combining the polymeric or pre-polymeric composition with a plurality of microparticles having a non-ferromagnetic or non-ferrimagnetic core provided with a coating that is ferromagnetic or ferrimagnetic to form an admixture in which the microparticles are substantially uniformly dispersed throughout the composition. The microparticles have a detectable magnetic characteristic which correlates with level of stress in the composition within a given volume. The change in the magnetic characteristic of the microparticles is then measured to determine the level of stress in the composition within a given volume.