We introduce the integration of organic, polarised light-emitting electrospun nanofibers and lab-on-a-chip microchannel geometries. The alignment and spinning electric field leads to ordered mesoscopic active areas, up to many mm(2), which exhibit polarised light emission and are fully compatible with microlithographies and microfluidics. We utilise the nanofibers demonstrating the photo-excitation of flowing dye chromophores in microchannels. This leads to easy decoupling the excitation and sample emission by polarisation analysers, thus remarkably increasing the imaging signal to background noise ratio.