Ion sensing with three-dimensional inductors with vertical winding

A method, comprising:

• sensing an ionized fluid via a first sensing membrane interacting with a first planar spiral inductor;
• charging the first planar spiral inductor via the first sensing membrane based on the sensing an ionized fluid, wherein the first planar spiral inductor comprises a planar spiral inductor comprising at least two metal layers of a metal stack connected to a semiconductor chip comprising a substrate and an integrated circuit, wherein the semiconductor chip defines a semiconductor plane having a semiconductor plane normal vector and the first planar spiral inductor defines a first inductor plane having a first inductor plane normal vector, wherein an angle between the semiconductor plane normal vector and the first inductor plane normal vector is between 1 and 90 degrees;
• measuring a change in quality factor or inductance of the first planar spiral inductor;
• and
• outputting a fluid property signal corresponding to the measured change in quality factor or inductance of the first planar spiral inductor.

A fluid property sensor semiconductor device comprising a planar spiral inductor in a metal stack, and made by a process, the process comprising:

• forming a metal stack on a semiconductor chip, wherein the metal stack comprises a plurality of metal layers, wherein the semiconductor chip comprising a substrate and an integrated circuit;
• forming a first planar spiral inductor in the metal stack, wherein the first planar spiral inductor comprises at least two metal layers of the metal stack, wherein the semiconductor chip defines a semiconductor plane having a semiconductor plane normal vector and the first planar spiral inductor defines a first inductor plane having a first inductor plane normal vector, wherein an angle between the semiconductor plane normal vector and the first inductor plane normal vector is between 1 and 90 degrees;
• configuring a sensing membrane to electrically communicate with the first planar spiral inductor when exposed to an ionized fluid;
• and
• configuring a fluid property measurement circuit to measure a quality factor or inductance of the first planar spiral inductor and output a fluid property signal.