Robust\nAnticorrosive\nPolymer Thin Film for Reliable\nProtection of Ingestible Devices

Ingestible\ndevices (ID) provide a safe and noninvasive\nmethod for\nmonitoring, diagnosing, and delivering drugs to specific sites in\nthe human body, particularly within the gastrointestinal (GI) tract.\nHowever, the GI environment is highly acidic and humid, which can\ncause IDs to fail, and their corrosion in the acidic environment can\ncause leaching of toxic metal ions, thereby substantially limiting\ntheir long-term use. Thus, an efficient method is required to protect\nIDs, especially in the chemically and mechanically harsh GI environment.\nHowever, an anticorrosive polymer coating that can safeguard IDs in\nthe GI environment without delamination or performance degradation\nhas not been developed to date. The protective layer must satisfy\nseveral critical requirements, e.g., high biocompatibility, mechanical\ndurability, and superior anticorrosion performance. This paper reports\na highly cross-linked but submicron-thick siloxane-based anticorrosive\npolymer thin film that can be deposited directly onto IDs without\ndamaging them. The 500 nm-thick cross-linked polymer coating demonstrates\nexceptional corrosion resistance and chemical and mechanical stability\nin the GI environment without cytotoxicity. A printed circuit board\n(PCB) coated with the developed ultrathin protective film sustained\nperformance after exposure to a pH 1.00 phosphate buffered saline\nsolution at 37 °C for 72 h without leaching of metal ions. The\nID continued to operate effectively under such challenging conditions;\nthus, the developed film is suitable for applications that require\nprolonged functionality, e.g., diagnostics, drug delivery, and continuous\nhealth monitoring in the GI tract.