Fabrication of wireless sensor platform on transparent flexible film using screen printing and via interconnect

We present a wireless sensor platform that is fabricated on transparent flexible substrate by means of screen printing. The platform is battery free with data and power transmission functions. The smart sensor, fabricated on polyethylene terephtalate (PET) film, is designed based on RFID technology. Using an additive patterning process known as screen printing, metallization on the polymer substrates is created. Both sides of the polymer substrate are printed with metallic patterns and connected with micro vias filled with a conductive paste. One side of the substrate consists of printed electrical traces for components like resistors, capacitors, transistors that would be mounted onto it; the other side consists of a printed inductive coil used for wireless data and power transmission. The micro vias, which have a diameter of 120 μm, are formed by mechanical punching and filled with conductive silver paste. The size of one sensor unit is approximately 2 cm × 1.5 cm; an array of 4×7 sensor units are printed over an area of 15 cm × 15 cm on a PET film. The advantages of using polymer substrate are weight reduction and its ability to flex. This paper presents the details of manufacturing processes, component assembly and functionality test.