Active hydrogel composite membranes for the analysis of cell size distributions

摘要

Active membranes with switchable pores that are based on hydrogels can be used to measure the cell sizedistribution in blood samples. The system investigated in the present research is based on a polyethyleneterephthalate (PET) membrane that is surface polymerized with poly(N-isopropyl acrylamide) (PNiPAAm) toform active pores of arbitrary geometry. The PET membrane provides the functionality of a backbone formechanical rigidity, while the soft PNiPAAm hydrogel forms the active pores. Modeling and simulation of theactive hydrogel behavior proved to adequately predict the opening and closing of the pores under applicationof an activating stimulus, e.g. temperature. The applied model is called Temperature-Expansion-Model anduses the analogy of thermal expansion to model the volume swelling of hydrogels. The Normalized ExtendedTemperature-Expansion-Model can englobe arbitrary hydrogels and large geometric displacements. Studies ofpore opening - performed by using commercial finite element tools - show good agreement of the experimentallymeasured shape change of active pores. Based on these studies, the particulate uid ow through the switchablepores is analyzed. Through application of a membrane process, i.e. a given variation of applied pressure andswitching stimulus for the hydrogel, the size prole of the blocking particles can be measured directly usingthe ux diu000berence under constant pressure. This allows the measurement of the cell size distribution in bloodsamples, e.g. to detect circulating tumor cells or anomalies in the distribution that hint to anemia.