In eq. 2, rL is the radius of the liposome, rPS,avg is the average PS radius, %ΔiPS,avg is the average percent resistive pulse blockage current of the PS nanoparticles, and %ΔiL is the percent resistive pulse blockage current of a liposome. Use of eq. 2 assume that the liposomes are spherical and that their lipid membrane presents an infinite resistance to ion fluxes. As shown in Figure , 90 nm radius PS nanoparticles produced an average blockage current of 1.52 ± 0.02% for a 111 ± 8 nm radius nanopipette orifice.