Suitable wall shear stress (WSS) measurements are important due to the wall being the point of many chemical interactions. This applies particularly to the vascular system where WSS is known to affect endothelial surface reactions. Measuring the near WSS is particularly difficult in the circulation, even with bulk flow approximations, due to the particulate nature of blood and the 3-dimensional nature of the system. Here a novel methodology using the M13 filamentous bacteriophage virus (BPV) is presented as a possible solution to this problem. The BPV is a 1μm long cylinder but with a diameter of around 7nm. In this case, the BPVs are cultured by incubation with E. coli and separated with polyethylene glycol, then purified using a caesium chloride gradient, has been fluorescently tagged along its length using fluorescein Isothiocyanate (FITC) or tetramethylrhodamine-6-isothiocyanate (TRITC, Invitrogen). The BPV has 2700 possible binding sites for FITC or TRITC and so is trivial to detect in a fluorescent wide-field microscope even with as little as 5% binding efficiently. Free dye was removed with a salt trap (PD10, GE Healthcare) or dialysis. Linear dichroism was used to determine alignment with shear rate in bulk solution. Additionally anti-collagen IV antibody was attached using a maleimide-cysteine reaction to one end of the BPVs prior to TRITC binding. This would enable the BPV to bind from one end to collagen coated glass flow sides and the other to align along the flow direction. Preliminary analysis and results are presented. Optical and Electron microscopy were used to observe the additional affect of the TRITC- BPVs to form longer nano-rope, assemblies more suited to low resolution visualisation techniques (Figure 1). In conclusion suitably bound fluorescent BPVs has the potential to detect wall shear direction suitable for microfluidic devices and the circulation including 3D capillary beds such as the glomerulus.