A plant leaf is a highly hierarchical and complex structure essential for plants to perform photosynthesis and to develop. It is also through the leaf and in particular through their stomata, openings used by the plant for gas exchange, that pathogenic fungus after germination penetrate the leaf and infect the plant. At the University of Manchester, we are developing a multi-material and multi-functional biosensor, with biological detecting elements, mimicking the structure of a plant leaf in terms of structure and topography and able to detect the presence of specific pathogens (e.g yellow rust, brown rust). This biosensor has been designed based on the concept of biomimicry to obtain an exact replica of the leaf structure as it sensing surface. A critical aspect is the fabrication of the upper layer, with a layer thickness ranging between 50 and 80 ?m, presenting stomata structures able to open and close depending on external stimuli (e.g. temperature). This paper describes the combined use of additive manufacturing (3D Printing) and shape memory materials (4D printing) to create such kind of layer. Different shape memory polymers (polyethylene terephthalate glycol, polyurethane), and their performance in terms of fabrication, shape changes, recovery and the ability to promote fungus germination is evaluated.