Multi-directional deposition in array fabrication

An apparatus for fabricating multiple chemical arrays on a substrate, each array having multiple rows of feature locations with arrays of different sets being arranged in a sideways orientation with respect to the rows, comprising:

• (a) a head with a drop dispenser;
• (b) a transport system to move the head relative to the substrate while maintaining a gap therebetween;
• (c) a processor which causes the head to dispense drops while relatively moving the head along a path which comprises:
• (i) moving in a direction along the rows of a first array set then moving in an opposite direction along the rows of a second array set, without intervening movement of the head in the opposite direction over all of the first array set;
• and
• (ii) repeating (i) with the second array set of an earlier cycle being the first array set of a later cycle.

A computer program product for use with an apparatus for fabricating multiple chemical arrays on a substrate, each array having multiple rows of feature locations with arrays of different sets being arranged in a sideways orientation with respect to the rows, the apparatus having:

• a head with a drop dispenser;
• a transport system to move the head relative to the substrate while maintaining a gap therebetween;
• and
• a processor which controls the head and transport system;
• the computer program product comprising a computer readable storage medium having a computer program stored thereon which, when loaded into the processor, performs the steps of dispensing drops from the head while relatively moving the head along a path which comprises:
• (i) moving in a direction along the rows of a first array set then moving in an opposite direction along the rows of a second array set without intervening movement of the head in the opposite direction over all of the first array set;
• and
• (ii) repeating (i) with the second array set of an earlier cycle being the first array set of a later cycle.