Ultrafast laser micromachining and patterning of thermal spray multilayers for thermopile fabrication

This work presents a conformal direct-write technique for rapid prototyping and manufacturing of high-density thermopiles. The technique combines thermal spray, which, as an additive process, produces blanket depositions of films and coatings, with ultrafast laser micromachining, a subtractive process to produce functional patterns. NiCr/CuNi-based (E-type) thermopiles with 19, 40 and 81 junctions have been fabricated and characterized. The electrical and thermal behavior is discussed as a function of load resistance and maximum power produced. Being made using thermal spray, these thermopiles are particularly well suited for high temperature and harsh environments.