Ion sensing inductors with biased deep trench

A method, comprising:

• sensing an ionized fluid via a sense electrode;
• charging a first deep trench isolation varactor via the sense electrode based on the sensing an ionized fluid, wherein the first deep trench isolation varactor comprises a conductor in a dielectric in a deep trench in a substrate, the conductor biased to create a depletion region in the substrate proximate the deep trench;
• inducing a change in a quality factor of an inductor via charging the first deep trench isolation varactor;
• measuring a quality factor of the inductor;
• and
• outputting a fluid property signal corresponding to the measured quality factor of the inductor.

A fluid property sensor made by a process comprising:

• etching a first deep trench in a substrate, the substrate doped to form a well;
• filling the first deep trench with a dielectric;
• placing a first conductor within the dielectric, the conductor biased to create a first depletion region proximate the first deep trench, wherein the first conductor and the first depletion region form a first deep trench isolation varactor;
• connecting a sense electrode to the first deep trench isolation varactor, wherein the sense electrode is operable to be electrically charged when interacting with an ionized fluid, wherein the sense electrode is operable to electrically charge the first deep trench isolation varactor;
• positioning an inductor proximate the first deep trench isolation varactor, wherein the inductor has a quality factor;
• and
• providing a fluid property measurement circuit operable to determine a change in the quality factor of the inductor and output a fluid property signal.