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 via 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.