Tip overlay for continuous flow spotting apparatus

A method of depositing at least one substance from a carrier fluid on a deposition surface, the method comprising:

• a) loading a carrier fluid having at least one substance into a first well of a spotter apparatus, wherein the spotter apparatus comprises:
• i) a loading surface including the first well and a second well;
• ii) an outlet surface, different than the loading surface, including a first opening and a second opening;
• iii) a first microconduit fluidly coupling the first well with the first opening;
• iv) a second microconduit fluidly coupling the second well with the second opening;
• and
• v) an overlay positioned on the outlet surface and penetrated by a deposition channel, wherein the deposition channel is situated to communicate carrier fluid among the first opening, the second opening, and a deposition surface when the overlay is pressed against the deposition surface, and
• b) flowing the carrier fluid in series from the first well, through the first microconduit to the deposition channel, through the second microconduit and into the second well, wherein the deposition channel directs at least one substance from the carrier fluid onto the deposition surface.