Multilayer hydrodynamic sheath flow structure

A sheath flow structure for suspending a particle in a sheath fluid, comprising:

• a primary sheath flow channel for conveying a sheath fluid;
• a sample inlet for injecting a particle into the sheath fluid conveyed through the primary sheath flow channel;
• a primary focusing region for focusing the sheath fluid around the particle in at least a first direction away from a first side wall, a second side wall and a third side wall of the primary sheath flow channel;
• and
• a secondary focusing region provided downstream of the primary focusing region for focusing the sheath fluid around the particle in at least a second direction away from a fourth side wall of the primary sheath flow channel.

A sheath flow structure for suspending a particle in a sheath fluid, comprising:

• a primary sheath flow channel for conveying a sheath fluid;
• a sample inlet for injecting a particle into the sheath fluid conveyed through the primary sheath flow channel;
• a primary focusing region for focusing the sheath fluid around the particle in at least a first direction, wherein the primary focusing region is formed by tapering the primary sheath flow channel from a relatively wide portion to a relatively narrow portion in a direction along which fluid flows therethrough;
• and
• a secondary focusing region provided downstream of the primary focusing region for focusing the sheath fluid around the particle in at least a second direction different from the first direction,
• wherein the sample inlet intersects the primary sheath flow channel at the relatively wide portion, and wherein the secondary focusing region is disposed along the relatively narrow portion of the primary sheath flow channel.