Beyond the on/off chip trade-off: A reversibly sealed microfluidic platform for 3D tumor microtissue analysis

•A reversibly sealed microfluidic platform for 3D tumor microtissue formation and analysis is developed.•After the assay, the resealable chip allows selective spheroid retrieval for in-depth analysis.•On and off-chip characterization of 3D microtissue is carried out.•Cytotoxicity effect of drug was analyzed by using three different methods (optical, fluorescence and scanning electron microscopy).•We analyzed the SEM images to study the morphology parameters of spheroids subjected to drug treatments.