Understanding how nanoparticles interact with lipid bilayers will potentially have high impact on the development of new drug delivery systems, and on the investigation of their cytotoxicity. If nanoparticles could be designed to change shape, size and softness once they reach the biomembranes or by external parameters like temperature, the delivery efficiency could be controlled. Here we will study the interaction of PNIPAM based microgel particles with lipid bilayers. Previous experiments, using confocal microscopy, QCM-D and ellipsometry, show that the mode of interaction changes depending on microgel conformation, i.e., whether they are expanded or collapsed. We propose to use neutron reflectometry to reveal the degree of penetration as a function of temperature. Off-specular reflection will allow us to probe possible organisation as suggested in the confocal images.