A device for the microstructured grafting of several proteins onto a substrate, comprising: a substrate, a layer of polyethylene glycol placed on the substrate, a matrix for propagating the light in a first structured pattern and comprising optical means for replacing the first structured pattern with a second structured pattern, a light source adapted for illuminating the matrix, microscope objective for forming, on the layer, a first microstructured image of the first pattern, a first container for receiving a first aqueous solution comprising a benzophenone and a first protein, a second container for receiving a second aqueous solution comprising benzophenone and a second protein, and a microfluidic circuit adapted for containing the first aqueous solution, comprising an opening for bringing the first solution into contact with the layer at the opening, wherein: the microfluidic circuit is adapted to be filled with the first aqueous solution so as to bring the first aqueous solution and the layer into contact, the first microstructured image of the first structured pattern being formed on the layer by means of the light source in order to photoprint the first protein on the layer, the microfluidic circuit comprises microfluidic means for replacing the first aqueous solution with the second aqueous solution so as to bring the second aqueous solution and the layer into contact, the first structured pattern being replaced by the second pattern in order to photoprint the second protein on the layer, and the matrix is a plane matrix of micromirrors propagating the light by reflection. a substrate, a layer of polyethylene glycol placed on the substrate, a matrix for propagating the light in a first structured pattern and comprising optical means for replacing the first structured pattern with a second structured pattern, a light source adapted for illuminating the matrix, microscope objective for forming, on the layer, a first microstructured image of the first pattern, a first container for receiving a first aqueous solution comprising a benzophenone and a first protein, a second container for receiving a second aqueous solution comprising benzophenone and a second protein, and a microfluidic circuit adapted for containing the first aqueous solution, comprising an opening for bringing the first solution into contact with the layer at the opening, wherein: the microfluidic circuit is adapted to be filled with the first aqueous solution so as to bring the first aqueous solution and the layer into contact, the first microstructured image of the first structured pattern being formed on the layer by means of the light source in order to photoprint the first protein on the layer, the microfluidic circuit comprises microfluidic means for replacing the first aqueous solution with the second aqueous solution so as to bring the second aqueous solution and the layer into contact, the first structured pattern being replaced by the second pattern in order to photoprint the second protein on the layer, and the matrix is a plane matrix of micromirrors propagating the light by reflection. the microfluidic circuit is adapted to be filled with the first aqueous solution so as to bring the first aqueous solution and the layer into contact, the first microstructured image of the first structured pattern being formed on the layer by means of the light source in order to photoprint the first protein on the layer, the microfluidic circuit comprises microfluidic means for replacing the first aqueous solution with the second aqueous solution so as to bring the second aqueous solution and the layer into contact, the first structured pattern being replaced by the second pattern in order to photoprint the second protein on the layer, and the matrix is a plane matrix of micromirrors propagating the light by reflection.