Laser processing of polymer thin films for chemical sensor applications

Contemporary and next-generation commercial and defense-related platforms offer countless applications for thin-film polymer coatings, including the areas of microelectronics, optoelectronics, and miniature chemical and biological sensors. In many cases, the compositional and structural complexity, and the anisotropy of the material properties preclude the processing of many of these polymers by conventional physical or chemical vapor deposition methods. The Naval Research Laboratory has developed several advanced laser-based processing techniques for depositing polymer thin films for a variety of structures and devices. The two techniques detailed in this work, matrix-assisted pulsed laser evaporation (MAPLE) and MAPLE direct-write (MAPLE DW), are based on the concept of laser absorption by a matrix solution consisting of a solvent and the desired polymer. MAPLE is a physical vapor deposition process that takes place inside a vacuum chamber, while MAPLE DW is a laser forward-transfer process that is carried out under atmospheric conditions. Both processes have been successfully used in the fabrication of thin films and structures of a range of organic materials and systems. Examples of their use in the fabrication of two types of chemical sensors, together with a comparison of the performance of these laser-processed sensors and that of similar sensors made by traditional techniques are provided. (C) 2002 Elsevier Science B.V. All rights reserved.