A cartridge includes a fluidically conductive floor element, a cover, and a film disposed between the elements. The cover or the floor element and the film include a filling opening for filling microfluidic channels in one of the elements having sample fluid. Pins engage in corresponding holes in the film and the associated element. By way of deforming a pin, a friction fit is produced with the wall of a hole, and a head contacting the associated substrate in a form-fitting manner is formed. A press tool is placed on a head end of a pin at a predetermined pressure, and heat transfer into the pin takes place during a weld time. The pin material is brought to above the glass transition temperature and/or the melting point, and a friction fit between the pin and the wall of the hole is formed by flowing the pin material in the hole.