NOVELTY - A method (M1) for applying material onto a substrate using a droplet printing technique and a gas stream guiding system, involves (A) releasing a gas stream comprising a carrier gas and droplets of a suspension of the material its precursor into the direction of the substrate; (B) maintaining a steady flow of the gas stream over a first period of time; (C) converting the steady flow of the droplets in the gas stream into a converging flow; and (D) contacting the resulting droplets of the suspension of the material or its precursor with the substrate.    USE - For filling vias which are present in an electronic device useful in the production of conductors for use in a printed circuit boards or a solar cells (claimed). Also useful in two-dimensional and three-dimensional bodies, electrical insulators, semiconductors, functioning prototypes, molds, tools and a large variety of articles such as custom jewelry, conductive tracks for printed circuit boards, solar cells, custom made medical implants, and small complex engineering parts such as pump rotors.    ADVANTAGE - The method provides a droplet printing technique which displays an improved focusing accuracy, despite the fact that the droplets are transported over a relatively long distance. The method allows a high aerodynamic focusing accuracy of the droplets resulting in products of high precision when compared to known products made by conventional droplet printing techniques.    DETAILED DESCRIPTION - Applying a material onto a substrate using a droplet printing technique and a gas stream guiding system, involves    (A) releasing a gas stream comprising a carrier gas and droplets of a suspension of the material its precursor into the direction of the substrate, where the droplets are produced using the droplet printing technique;    (B) maintaining a steady flow of the gas stream over a first period of time, where the Stokes number of the droplets in the gas stream is less than 1 during the first period of time;    (C) converting the steady flow of the droplets in the gas stream into a converging flow and maintaining the converging flow of the droplets over a second period of time, where the Stokes number of the droplets in the gas stream increases up to a value higher than 10 during the second period of time; and    (D) contacting the resulting droplets of the suspension of the material or its precursor with the substrate.    An INDEPENDENT CLAIM is included for an apparatus for carrying out a method comprising a reservoir for a suspension of the material or a solution of a precursor of the material; a printing head for releasing droplets of the suspension or the solution, which printing head is connected to the reservoir; a gas stream guiding system which comprises a first part having essentially the same diameter over essentially its entire length, and a second part having with a converging diameter over essentially its entire length.    DESCRIPTION OF DRAWING(S) - The figure shows schematic lay-out used for carrying the method (M1) for applying material onto a substrate using the droplet printing technique method.