Reports have recently been published on ultrathin biofluid barriers, which enable the long-term measurement of biological signals and exhibit conformability on nonlinear surfaces such as skin and organs. However, inorganic- and organic-based barriers have process incompatibility and high water permeability, respectively. Siloxane- (inorganic) based fluorinated epoxy (organic) hybrid materials (FEH) are demonstrated for bio-fluidic barrier and the biocompatibility and barrier performance for flexible electronic systems as solution-processed oxide thin-film transistors (TFTs) on 1.2 mu m thick polyimide (PI) thin film substrate is confirmed. FEH thin film can be patterned as small as 10 mu m through conventional photolithography. The fabricated solution-processed indium oxide TFTs with FEH barriers exhibit durable performance over 16 h with no dramatic change of transfer characteristics in phosphate-buffered saline (PBS) environment. Furthermore, to realize FEH barriers for flexible systems, the solution-processed indium oxide TFTs with FEH barriers on ultrathin PI substrate are demonstrated subjected to compression test and successfully measure the electrical properties with no irreversible degradation during 1000 cycles of mechanical testing in PBS.