One of the major obstacles preventing the development of implantable biosensors, artificial kidneys, and other “active” medical devices requiring a controlled implant-tissue interface has been the reduction in device function after implantation. The major difficulty in creating implantable active medical devices that function for long periods of time is poor control over materials-tissue interaction. Several materials have previously been considered for reducing protein adsorption, promoting integration of the medical device with the surrounding tissues, and maintaining transport of biological molecules between the device and the surrounding tissues over an extended period of time. The surfaces of these materials must be sufficiently thin and porous in order to allow the devices to rapidly respond to variations in biological molecule concentration. Unfortunately, hydrogels, phospholipids, surfactants, and flow-based systems have not generally been successful in maintaining a selectively permeable in vivo tissue-material interface. On the other hand, nanoporous ceramics such as anodized aluminum oxide are similar in structure to natural filters within the human body (e.g., glomerular basement membrane in the kidney). Unlike polymers, ceramics generally demonstrate corrosion resistance, wear resistance, and biologically inert behavior for long periods of time. Roger Narayan at the University of North Carolina (UNC) at Chapel Hill in collaboration with Jeffrey Elam and Michael Pellin at Argonne National Laboratory [Narayan, et al., Biomed. Mater. (2008) 3, 034107] have used atomic or pulsed layer deposition to modify the surfaces of these nanoporous membranes. The atomic layer deposition process is particularly attractive as it allows one to reduce the pore diameter while retaining a narrow pore size distribution. The UNC-Argonne group has developed several nanoporous ceramic membranes for use in active medical devices. For example, membranes have been functionalized with diamond-like carbon or poly(ethylene) glycol in order to minimize protein adsorption. The group is also looking into the possibility of integrating smart capabilities into functionalized nanoporous ceramic membranes, such as the incorporation of biomimetic technologies to further control nanopore diffusion characteristics.