Design and optimization of a microfluidic-based inductor used as a multifunction-sensor

A planar miniaturized inductor has been designed in order to realize some transduction functions linked to the presence of fluids. Its electrical behavior has been studied for two liquids: Galinstan (an alloy of GALium INdium STANum) and salted water. Their presence between metallic armatures modifies the inductance value at a nominal frequency, chosen at 2GHz. By using a FEM software, the spatial distributions of magnetic field and surface current density in the entire device have been modelized for six arbitrary positions of these liquids in inductor microchannels. The geometrical aspects of the device have been studied and their influence examined for each liquid. We show that the inductor performances are influenced by the spiral width variations and the inter-turn distances of the coil. Considering the device as a sensor, we have evaluated the variations of two parameters: inductance and quality factors, which can respectively attain 664% (for Galinstan) and 175% (for salted water) from their nominal values.