Fabrication of dry-patching superhydrophobic flexible platform for HySiF (hybrid system in flexible) applications

As the performance of flexible devices including HySiF (hybrid system in flexible) applications has been increased with maintaining its mechanical flexibility, the concept for HySiF is considered as the next generation technology which can possibly open a huge/various/new market. Since HySiF applications can target for various areas such as wearable devices, flexible sensors, flexible display, etc., we think there should be a strong need for the platform of the flexible substrate that can be utilized to any kind of HySiF applications. In order to provide the flexible platform, we focused on the fabrication of a dry-patching superhydrophobic (contact angle >150°) flexible substrate using a solution based polymer casting method by adapting a stamping method for future mass production. While there are two different patching types such as wet-patching and dry-patching, we chose to utilize the dry-patching way because it lasts the patching performance very long without any further or extra treatment (longer than a month). In addition, to create the superhydrophobic characteristic of the substrate, we used a solution based transparent polyimide and fabricated pillar structures (pillar height=30um) which play a crucial role to change the surface condition from Wenzel state to Cassie-Baxter state (contact angle >150°) by creating the air pocket effect between the pillars. With those work, we also achieved a very low hysteresis contact angle (<10°) providing a self-cleaning effect on the surface the can also be a critical factor for a long term use and reliability. With achieving the superhydrophobicity, we also maximized the transparency of the platform substrate by controlling the gap of the pillars (10∼90 um). Finally, we expect that our platform work can help the HySiF target product to commercialize in the near future.