Abstract: A method of producing a microfluidic chip for use in flow cytometry, the method comprising the steps of providing an opaque substrate, a first surface of which is optically smooth for visible light providing a continuous transparent layer across said first surface by vapour deposition so as to provide conformal contact between the continuous transparent layer and the first surface of the substrate providing a flow channel bounded on a first side by the continuous transparent layer and etching an aperture in a second surface of the substrate extending to the first surface of the substrate so as to provide an optical path between said second surface and the flow channel wherein the continuous transparent layer is less reactive to the etching than the substrate.

Abstract: A single junction sorter for a microfluidic particle sorter, the single-junction sorter comprising: an input channel, configured to receive a fluid containing particles; an output sort channel and an output waste channel, each connected to the input channel for receiving the fluid therefrom; a bubble generator, operable to selectively displace the fluid around a particle to be sorted and thereby to create a transient flow of the fluid in the input channel; and a vortex element, configured to cause a vortex in the transient flow in order to direct the particle to be sorted into the output sort channel.

Abstract: A method of selecting a type of particle for use in standardisation and/or calibration of a flow cytometer. The method includes determining the location of two or more particle focal points of particles flowing through a cross section of a channel in the flow cytometer; for each type of particle, determining for each particle focal point, for a beam of light directed at a type of particle at said particle focal point from a first direction, the total intensity of light scattered along a second direction; determining the difference between the highest and lowest determined light intensities of the light intensities determined at the two or more particle focal points; and selecting a type of particle for which the difference between the highest and lowest determined light intensities at the two or more particle focal points is below a predetermined threshold.

Abstract: A single junction sorter for a microfluidic particle sorter, the single-junction sorter comprising: an input channel, configured to receive a fluid containing particles; an output sort channel and an output waste channel, each connected to the input channel for receiving the fluid therefrom; a bubble generator, operable to selectively displace the fluid around a particle to be sorted and thereby to create a transient flow of the fluid in the input channel; and a vortex element, configured to cause a vortex in the transient flow in order to direct the particle to be sorted into the output sort channel.