Fabrication of polymers and composites containing embedded sensors

Freeform fabrication is a family of techniques for preparing solid objects from a 3D computer- based design. The best known method is stereolithography. To date, freedom fabrication has been mainly applied to making prototypes and molds. Similar techniques can be applied to make functional parts of a range materials, including metals and ceramics as well as polymers. In collaboration with Advanced Ceramics Research Corp. of Tucson, Arizona, we have been developing a reactive extrusion method where a part is built up by extrusion of a material stream through a fine needle. A curing reaction at the deposition site allows solid components to be formed. This approach can be readily modified to deposit several materials in the same part and hence to fabricate intelligent materials containing embedded sensors and actuators. This paper describes the application of this method to an epoxy part containing an optical fiber sensor and the response of embedded polyvinylidenefluoride piezoelectric films.