Method and system for microfluidic particle orientation and/or sorting

A microfluidic system for sexing sperm comprising:

• at least one channel suitable for fluid flow within the channel comprising at least one input source and at least two output sources, and a plurality of stages arranged along the channel;
• an orientation stage following, and in fluid communication with, the at least one input source, the orientation stage comprising at least one optical waveguide arranged and configured to expose sperm to radiation pressure to cause at least a majority of the sperm to adopt a particular orientation in the fluid flow;
• a detection stage following, and in fluid communication with, the orientation stage, the detection stage comprising an optical detector configured to discriminate between male and female sperm in the fluid flow past the detection stage, and
• a switching stage comprising a plurality of optical waveguides arranged such that sperm flow past each optical waveguide in the plurality, said optical waveguides arranged and configured to expose sperm to radiation pressure to cause a change in direction of movement of selected male or selected female sperm in the fluid flow to sort the selected male or selected female sperm into one of the at least two output sources based on input from the detection stage, and a controller.