A method for fabricating an apparatus comprising at least one microfluidic channel within an anisotropic composite material structure comprising multiple electrically and thermally conductive pathways, the method comprising providing an electrode within a composite material, the electrode positioned in a desired location for a microfluidic channel applying an electric field across at least a portion of the composite material using the electrode whereby to define the pathways and curing the composite material whereby to fix the pathways in position in the composite material.