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:
Mar. 01, 1994
Filed:
Jul. 14, 1992
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method of making a capillary tube for providing increased control of electroosmotic flow in electrophoretic separation. A resistive coating solution is formed so that a tube coating having a high electrical resistivity may be achieved. An electrically conductive material, such as carbon black, is homogeneously mixed with a polymer, such as polyimide, in a solvent. The content by weight of the electrically conductive material is less than 20 percent and is preferably within 7 percent to 8 percent, relative to the content by weight of the polymer. The resistive coating solution is applied to the exterior of the tube until a thickness is reached which achieves a desired resistance across the coated exterior surface. Typically, a multi-layered coating is formed. The coating solution may be applied while rotating the capillary tube or, alternatively, while the capillary tube is drawn past an applicator.