Fabrication of perforated polyethylene microfiltration membranes for circulating tumor cells separation by thermal nanoimprint method

Size-based filtration has been proved an efficient and quick approach to separate circulating tumor cells (CTCs) from other blood cells for cancer diagnosis and therapy monitoring. In this work, we proposed a simple, cost efficient and scalable approach to fabricate microporous polyethylene (PE) membranes for CTC filtration by thermal nanoimprint method. PE was selected as the material for the membrane due to its commercially available films with a thickness as thin as 10 mu m, which is matched well with the size of the micropores for CTCs and critical to a successful nanoimprint with a low and uniform residual layer. A thermal imprint process with a nickel mold was applied to fabricate periodic microporous PE membranes with a pitch of 20 mu m and diameter of 10 mu m. The perforated micropores were obtained by a short time O-2 plasma-etching to remove the imprint residual layer. This PE membrane microfilter achieved 84% average capture efficiency for lung cancer cells spiked in blood samples.