Features..... | .....The growth technology

 

The transfer technology

After the nanofibers have been grown, they have to be transferred from mica to another storage medium for further handling. The most promising storage medium is thin (50 micrometer) polyester (PE) foil. Immediately after growth, the nanofiber on mica sample is placed in a high humidity atmosphere. Small water drops in the air will release the nanofibers from the mica surface. The PE foil is placed on top of the mica sample and the PE foil is then conformed to the mica/nanofiber surface by applying air pressure to the back side of the PE foil. The PE foil is removed and the nanofibers are now sticking to the PE foil. After this a new transfer can be made and the foil with nanofibers can be rolled up (like an old-fashioned typewriter band) for easy storage. The nanofibers are released from the foil by pressing the foil towards the substrate one wants the nanofibers transferred to. For the latter process no humidity is needed.

Advantages

  • The technique is very simple to handle and the polyester foil is very cheap.
  • Polyester is a flexible storage medium, which can be implemented in various production lines especially in the security label business where handling of thin foils already is well implemented.
  • The nanofiber on foil is a replica of the nanofiber on mica, i.e. a rectangle (25x75 mm) on foil is produced where all the nanofibers are pointing in the same direction (if they did this on the original growth substrate).

Disadvantages

  • Although on a naked-eye level no damage is visible, on a microscopic level the nanofibers might be damaged or misaligned at some instances during the transfer process. Also, there are some limits for hot embossing processes in terms of temperature resistance of the foil. Details about this subject are available.