Pore imprinted polymer (PIPS) method. A section of thermoplastic polyurethane (PU; Delstar EU40, 36 m in thickness, obtained from SWM) was mounted onto a sheet of aluminium foil. The membrane was then placed on top of a hotplate and a weighed tungsten needle (from Agar Scientific) positioned on top of the membrane. A temperature of 50 o C softened the membrane sufficiently to pierce with the tungsten needle without changing the membrane's physical characteristics. A higher temperature of 55 o C caused the membrane to discolour, with bubbles beginning to form. At 60 o C, the membrane became very malleable and was too difficult to handle. Two methods were evaluated to prepare the pores. The first was the aforementioned approach, where a weighted needle was placed on top of the membrane during the heating process. The second investigated if the pores would shrink or reseal upon heating. This involved heating a previously prepared pore back to the fabrication temperature, with the pore's size and shape recorded before and after heating.