Abstract: A method for monitoring the production of a material such as graphene in a liquid dispersion in real time, comprises supplying the liquid dispersion to a fluid gap defined between a first layer and an opposed second layer, wherein the first layer is light-transmissive and wherein the second layer has a diffusely reflective surface facing the first layer. The diffusely reflective surface is illuminated with light from a light source and light reflected from the diffusely reflective surface is detected at an associated photodetector. A light path from the light source to the photodetector comprises the light passing through the transmissive layer towards the diffusely reflective surface through the fluid gap, reflecting off the diffusely reflective surface and passing back through the fluid gap towards and onwards through the transmissive layer. The concentration of the material in the liquid dispersion can be determined from the detected reflected light.

Abstract: The invention provides an apparatus for fluidic exfoliation of a layered material comprising: a housing of circular cross-section defined by a housing wall; a hollow rotor of circular cross-section having a first end and a second end and a wall positioned therebetween arranged concentrically within the housing, wherein the wall of the hollow rotor defines an inner chamber and the space in between the wall of the hollow rotor and the housing wall defines an outer chamber, and wherein a fluid flow path is provided between the inner chamber and the outer chamber; a fluid inlet in fluid communication with the inner chamber or the outer chamber; and a fluid outlet in fluid communication with the other of the inner chamber or the outer chamber; wherein the outer chamber has a width such that on passage of a fluid comprising the layered material from the inlet to the outlet through the outer chamber, a shear rate sufficient to exfoliate the layered material may be applied to the fluid comprising the layered material