Inductive Sensor with Contactless Interrogation for Conductive Target Detection
Marco Zini, Marco Baù, Alessandro Nastro, Marco Ferrari, Vittorio Domenico Ferrari · 2024
The contactless interrogation of an inductive sensor (IS) for conductive target detection is presented. The IS comprises a solenoidal coil of copper wire wrapped around a plastic pipe which is connected to a series capacitor to form an LC circuit resonating at the frequency fr. A conductive target placed at different positions inside the pipe modifies the inductance of the coil, and in turn, fr. An external interrogation coil (IC) electromagnetically coupled to the IS allows the fr to be read through a contactless interrogation technique. The approach has been tested by varying both the position of a lead sphere adopted as the target and the interrogation distance d between the IS and IC. Without the sphere, the LC circuit has fr0 = 2.51 MHz. The target sphere has been detected at up to |x| = 7.5 mm from the center of the IS coil with a frequency variation ∆ fr = 180 kHz at x = 0.