Encapsulated Copper Wire and Copper Mesh Capacitive Sensing for 3-D Printing Applications

Advances in the field of extrusion based 3-D printing have recently allowed the incorporation of embedded electronics and interconnects, in order to increase the functionality of these structures. This paper builds on previous work in the area of fine-pitch copper mesh and embedded copper wire capacitive sensors encapsulated within a 3-D printed structure. Three varieties of sensors were fabricated and tested, including a small area wire sensor (320-μm width), a large area mesh sensor (2 cm²), and a fully embedded demonstration model. In order to test and characterize these sensors, three distinct tests were explored. Specifically, the capacitive sensors were able to distinguish between three metallic materials and distinguish salt water from distilled water. These capacitive sensors have many potential sensing applications, such as biomedical sensing, human interface devices, material sensing, electronics characterization, and environmental sensing. As such, this paper also characterizes the capacitive sensors for an active microfluidic mixer.