Free-floating hydrogel-based rafts supporting a microarray of functional entities at fluid interfaces

In the present paper, we report a method for fabricating a macroscopic, free-floating device that supports a microarray of molecular functional entities. Therefore, the fabrication process developed by us combines bottom-up and top-down microfabrication strategies for a spatially controllable integration of molecular entities into the macroscopic device. For application, the generated device is transferred to fluid interfaces. Through a combined experimental and theoretical study, we demonstrate that the microscopic cavities of the intrinsically hydrophilic comb-shaped mesh structure enable the flotation of the device at a water-air interface of a sessile droplet due to surface tension effects. The design of the functionalized and free-floating device affords a long-term stable approach with respect to a chemical patterning of this fluid interface without loss of the lateral arrangement of the functional entities over time.