Air-channel fabrication for microelectromechanical systems via sacrificial photosensitive polycarbonates

This research involves the fabrication of encapsulated air-channels via acid-catalyzed degradation of photosensitive polycarbonates (PCs). There is a need for lower-temperature, degradable polymeric materials to fabricate buried air-channels for microelectromechanical systems (MEMS), microfluidic devices, and micro-reactors. Some polycarbonates undergo thermolytic degradation in the temperature range of 200 to 350°C. These polycarbonates are also known to undergo acid-catalyzed decomposition in the presence of catalytic amounts of acid. A small percentage of an acid in the polycarbonate formulation can greatly reduce the onset of decomposition temperature to the 100 to 180°C temperature range. The photoacid and thermal acid induced degradation behavior of PCs and its use as a sacrificial material for the formation of air-gaps have been studied in this work. The decomposition of several polycarbonates with the aid of in situ generated photo-acid has been demonstrated and applied to the fabrication of micro air-channels. Based on FT-IR, mass spectrometry, and thermogravimetric analysis (TGA), a degradation mechanism was proposed.