Liquid repellent fibrillar dry adhesive material and a method of producing the same

A method of producing a fibrillary dry adhesive material having a plurality of fibrils, the fibrils having a tip and a body, the tip having a larger outer dimension than the body, wherein the fibril tip comprises a double re-entrant tip geometry, which comprises a mushroom shape with an undercut remote from a top surface of the fibril tip, the method comprising the following sequence of steps:

• a) providing a negative mold having a surface and comprising cavities having a shape corresponding to an outer shape of the fibrils to be produced, wherein the mold is formed of a first material, either
• b1) activating said surface and said cavities of said mold and then passivating the first material by providing a silane another chemical treatment to the activated first material;
• or
• b2) providing a polymer coating to said surface and said cavities;
• and then
• c) applying vacuum to remove air out of the cavities;
• d) filling the cavities with a second material;
• e) curing the second material to produce at least the fibrils optionally keeping some of the second material as a backing substrate to hold the fibrils together;
• and optionally
• f) demolding the first material from the second material to obtain said fibrils at said second material.