Controlling nanofiber sheet width

Abstract

Techniques are described for controlling widths of nanofiber sheets drawn from a nanofiber forest. Nanofiber sheet width can be controlled by dividing or sectioning the nanofiber sheet in its as-drawn state into sub-sheets as the sheet is being drawn. A width of a sub-sheet can be controlled or selected so as to contain regions of uniform nanofiber density within a sub-sheet (thereby improving nanofiber yarn consistency) or to isolate an inhomogeneity (whether a discontinuity is the sheet (e.g., a tear) or a variation in density) within a sub-sheet. Techniques for dividing a nanofiber sheet into sub-sheets includes mechanical, corona, and electrical arc techniques.

What is claimed is: 
     
         1 . A method for dividing a nanofiber sheet, the method comprising:
 configuring a structure to have at least one salient feature comprising an edge, and at least one reverse salient feature;   contacting the nanofiber sheet with an edge of the at least one salient feature; and   drawing the nanofiber sheet past the at least one salient feature while maintaining contact therebetween, the drawing causing the nanofiber sheet to be dividing into sub-sheets.   
     
     
         2 . The method of  claim 1 , wherein a width of the at least one salient feature is at least 1 μm. 
     
     
         3 . The method of  claim 1 , wherein a height of the at least one salient feature is at least 1 μm. 
     
     
         4 . The method of  claim 1 , further comprising identifying an inhomogeneity in the nanofiber sheet, and wherein dividing the nanofiber sheet comprises dividing the nanofiber sheet into at least a first sub-sheet and a second sub-sheet, the inhomogeneity disposed entirely within the first sub-sheet. 
     
     
         5 . The method of  claim 4 , wherein the inhomogeneity is a tear in the nanofiber sheet or a variation in a number of nanofibers per unit volume of the nanofiber sheet. 
     
     
         6 . The method of  claim 4 , wherein at least one of the first or second sub-sheets is less than 5 μm in width. 
     
     
         7 . The method of  claim 6 , further comprising spinning a nanofiber less than 1 μm in diameter from the sub-sheet less than 5 μm in width.