Microfluidic flow-through elements and methods of manufacture of same

A process for forming a microfluidic nozzle tip, the process comprising:

• providing a polymeric base substrate having a conical flow path surface converging from an upstream end toward a closed end wall at a downstream end, the closed end wall having an upstream surface, a downstream surface, and an end wall dimension defined between opposing conical surfaces;
• aligning a laser beam relative to the polymeric base substrate;
• focusing the laser beam in a focal plane that is downstream or upstream of the closed end wall;
• impinging the laser beam onto the upstream surface or the downstream surface of the closed end wall, the laser beam having a corresponding impinging cross-sectional beam dimension that is larger than the end wall dimension;
• and
• forming an orifice extending from the upstream surface to the downstream surface of the end wall with the laser beam, the orifice having an upstream orifice portion that converges in a downstream direction and smoothly merges with the conical flow path surface at a transition region, the orifice having a downstream orifice portion that is non-converging.

A process for forming a microfluidic nozzle tip, the process comprising:

• providing a polymeric base substrate having a flow path converging toward a closed end wall having an upstream surface and a downstream surface;
• aligning a laser relative to the polymeric base substrate;
• directing a beam from the laser in the flow-path direction;
• and
• impinging the beam from the laser onto the upstream surface of the closed wall of the polymeric base substrate to form an orifice extending from the upstream surface to the downstream surface of the end wall of the polymeric base substrate, the beam from the laser removing material from the upstream surface of the flow path relative to the end wall, the orifice having a converging upstream orifice portion and a downstream orifice portion, and the upstream orifice portion smoothly merges with the flow path at a transition region between the flow path and the upstream orifice portion.