Abstract: The invention relates to a method of the dosed application of a liquid onto to selected portion of the surface of a substrate (A) by means of spraying under the influence of an electric current. According to the invention the liquid is fed at a flow rate between 0.01 pl/s and 1 ml/s to a distal tip (3) of a capillary (1) having an inside diameter of less than 150 ?m, wherein the distance between the distal tip and the surface (A) is less than 2 mm. Surprisingly it has been shown that it is possible in this manner to apply liquid to a restricted surface of a defined size.

Abstract: The invention relates to a method of filling a well (including a channel) in a substrate. In accordance with the invention liquid is applied on a substrate comprising a well on a position that does not coincide with the well, and the well after filling is sealed with a cover means, wherein liquid is applied on a position between the front of the cover means and the well that is not covered by the cover means, and with the aid of the cover means the liquid is pushed into the well.

Abstract: The invention relates to device for carrying out a reaction, which device comprises a substrate (2) provided with a well (4) for carrying out the reaction, and a cover means (3). According to the invention the cover means (3) is provided with an aperture (5), which in a first position does not overlap the well (4), while in a second position overlapping the well at least partly. Such a device can be filled in a simple manner and evaporation of liquid from the well (4) is to a large extent prevented. The invention also relates to a method for carrying out a reaction in a device according to the invention.