Structural Deformation using Metal Deposition for Bio-Adhesive Patch

Recently, adhesive patches have been studied for medical treatment. Depending on their characteristics, these can be applied in various situations such as wound healing, drug delivery, and biosensor attachment. Given that the body is a moist environment, current research focuses on incorporating chemical adhesives or utilizing structural properties for surface attachment such as suction effects. Additionally, liquid-repellency is essential to prevent the risk of detachment caused by wetting. We adopted structural adhesives to avoid allergic reaction due to toxicity of chemical adhesives. This research presents a method of structural deformation through different metal deposition on hyperbola structure to achieve new properties such as wet adhesion (Au) or liquid-repellency (Al). Hyperbola structures were fabricated by wrapping liquid prepolymer around micropillars driven by capillary force. Due to its flexible edges, the metal, deposited on top surface, caused structural deformation depending on its residual stress. In the case of Au, tensile stress of Au thin film made edges shrink inward, created an empty space inside for adhesive behavior. Conversely, in the case of Al, edges expanded outward because of compressive stress of Al thin film caused by oxidation. So, this structure had more liquid-repellency characteristics. These novel structures can be easily replicated and mass-produced using soft lithography, offering the advantage of non-allergic reactions as no additional adhesives are required. Furthermore, deformation can be easily controlled by adjusting the deposition thickness and Young's modulus of the structure's material. This technology is expected to contribute to the medical industry as for skin/organ-attachable patches.