A method of treating an isolated area of a sample with a liquid is disclosed. The method has the steps of generating an isolated area of a sample by a first fluid reservoir where the first fluid reservoir enclosing a distal end of a second fluid reservoir and the isolated area of the sample being sealed towards the remaining area of the sample, bringing the isolated area of the sample into fluid connection with the second fluid reservoir, dispensing a fluid from the second fluid reservoir into the first fluid reservoir thereby generating a fluid flow on the sample at the isolated area in a first direction, and aspirating the fluid from the first fluid reservoir into the second fluid reservoir thereby generating a fluid flow on the sample at the isolated area in a second direction.