A method for washing particles includes obtaining an array plate that includes an array of hydrophilic areas surrounded by one or more hydrophobic areas. A respective solution containing a sample is located on a respective hydrophilic area of the array of hydrophilic areas. The respective hydrophilic area includes one or more indentations from a respective surrounding hydrophobic area of the one or more hydrophobic areas. The respective hydrophilic area includes a first indented surface that is offset from a reference surface defined by the respective surrounding hydrophobic area. The method also includes placing an aspirator nozzle above the respective hydrophilic area at a predefined distance from the first indented surface, and aspirating the solution with the aspirator nozzle while the aspirator nozzle is located at the predefined distance from the first indented surface.
