An alternative approach to nanopore fabrication is to puncture sheets of polyurethane (PU) with needles. Here we attempted a similar process to produce polymer imprinted pores (PIPs) as described in the experimental methods vide supra. Examples of pores produced by this method are shown in figures S4c,d. Table summarises the large range in diameters, from 5 to 50 µm, for the PIPs produced. While reproducibly controlling their size and shape was not possible using the current set-up, the PIPs were easily wet with electrolyte solution and data was collected for the detection of particles as small as 2 m in diameter using 11 m diameter pores (figure ). Thus, with PIPs, pores may be produced easily within a limited set-up but with the trade-off of significantly reduced reproducibility.