Apparatus and method for transfering small volumes of substances

An apparatus for spotting a reagent onto one or more substrates, comprising:

• a conveyor belt comprising a plurality of substrate-support regions separated from one another by intervening open regions therebetween;
• a base located beneath the conveyor belt for supporting one or more reagent reservoirs;
• a transfer head, disposed above said base and said conveyor belt, which has a reagent spotting tip mounted for movement between (1) a raised position above the conveyor belt, (2) a reagent dispensing position for depositing reagent on a substrate carried by one of said substrate-support regions, and (3) an extended position below the conveyor belt which is achieved by passing the tip through one of said open regions;
• means for moving the conveyor belt along a transport pathway such that the substrate-support regions pass between said base and said transfer head;
• means for shifting the spotting tip between said extended, reagent dispensing, and raised positions;
• and
• one or more controllers operatively connected to the moving means and shifting means effective to (i) shift the spotting tip from its raised position to its extended position by traversing a selected open region in said conveyor belt, for withdrawing reagent from a reservoir supported by the base, (ii) raise the spotting tip after step (i) to a position above the conveyor belt, (iii) move the conveyor belt so that a selected substrate is positioned below the raised spotting tip, (iv) move the spotting tip to a reagent dispensing position so that reagent is deposited onto a selected region of the selected substrate, (v) after reagent deposition, raise the spotting tip to its raised position, (vi) move the conveyor belt so that the spotting tip is positioned above another open region, and (vii) repeat steps (i) through (vi) a selected number of times.

An apparatus for spotting a reagent on one or more substrates, comprising in operative condition:

• a base adapted to hold such a reagent;
• a conveyor having a surface defining (i) a plurality of spaced, tandemly-arranged substrate regions, and (ii) an opening between each adjacent pair of substrate regions;
• said conveyor being operable to advance such regions along a transport pathway over said base;
• a transfer head having a spotting tip, said tip being mounted for movement along an axis, toward and away from a raised position at which the tip is disposed above the conveyor surface;
• an actuator operatively connected to said tip for moving the same along said axis;
• and
• a control unit operatively connected to the conveyor and actuator, operative, for one or more selected substrate regions defined by the conveyor surface, to (i) shift said tip away from its raised position through a selected opening in said conveyor surface to contact reagent in said base, (ii) withdraw said tip from the reagent and through the opening by shifting the tip toward its raised position, and (iii) shift said tip away from its raised position toward a selected substrate region upstream of the selected opening, to transfer a selected amount of reagent from said tip to a selected site of the selected substrate region.

A method for spotting a reagent on one or more substrates, comprising the steps of:

• (i) advancing a plurality of spaced, tandemly-arranged substrates along a transport pathway extending over a reagent-supply location;
• (ii) from a position over said reagent-supply location and said pathway,
• (a) extending a reagent-transfer instrument through an intervening region separating an adjacent pair of advancing substrates to contact reagent held at said reagent-supply location,
• (b) withdrawing the reagent-transfer instrument, along with a portion of such reagent, through said intervening region to a position above said transport pathway, and
• (c) transferring a selected amount of reagent from said reagent-transfer instrument onto a selected region of a selected substrate upstream of said intervening region.