Printed coil sensors for monitoring fluid condition

A system for monitoring one or more properties of a fluid in a mechanical device, the system comprising:

• a printed circuit board (PCB)-based inductive sensor for detecting one or more metallic particles in the fluid, the PCB-based inductive sensor comprising:
• a first PCB, a second PCB and a third PCB, the first PCB comprising a first field coil trace printed on one or more layers of the first PCB, the second PCB comprising a sense coil trace printed on one or more layers of the second PCB and the third PCB comprising a second field coil trace printed on one or more layers of the third PCB, and
• a mesh structure, wherein the first PCB, the second PCB and the third PCB comprise one or more apertures, the one or more apertures being aligned and allowing the fluid to pass through, wherein the first field coil trace, the sense coil trace and the second field coil trace are wound around each aperture,
• wherein the first field coil trace and the second field coil trace generate a magnetic field when electrically driven and the sense coil trace detects a change in the magnetic field produced by the one or more metallic particles in the fluid.