Pattern formation of a thin film is characteristically sensitive to chemical stimuli

The surface structure of a soy milk skin, as a simple artificial film, was found to be characteristically sensitive to chemical stimuli. The surface structure of the film was imaged by AFM and the shape and size of concavities on the film were analyzed to characterize the chemical response. This characteristic pattern formation of the soy milk skin is discussed in relation to the surface aggregation, electronic charge and solubility of soy protein molecules around the air/water interface. We believe that the investigation of such an artificial film prepared under nonequilibrium conditions could lead to the creation of a novel artificial film that can variously form the spatial structure to the chemical environment.