Dynamic phase control with printing and fluidic materials' interaction by inkjet printing an RF sensor directly on a stereolithographic 3D printed microfluidic structure.

Abstract

Stereolithographic (SL) three-dimensional (3D) printing of microfluidic channels and inkjet printing of radio frequency (RF) electronics are promising lab-on-a-chip technologies. However, the effective integration of the two techniques has been challenging since the fabricated parts need to be combined <i>via</i> an additional bonding process, such as plasma bonding. This study proposes combining RF electronics with SL printed microfluidic structures by directly inkjet printing onto a 3D printed mould. This allows the inkjet printing of RF electronics with high conductivity (8 × 10⁶ S m^-1) and high resolution (50 μm) as a surface modification of the 3D printed mould. This process combines the three-dimensional printing of microfluidic parts and the inkjet printing of RF sensors into a single process. The proposed approach increases the interaction between a printed RF part and a fluid material by adjusting the distance between them, and it can be applied to various resins and 3D printing methods. Furthermore, the proposed fabrication process was applied to a dynamic phase advanced and delayed transmission line (TL) operating at 3.8 GHz as a fluidic sensor. Consequently, using the same pattern, a higher phase shift range per microliter of 10° was obtained than the 1° for conventional phase shift TLs.