Single electrode capacitance sensor for measurement of liquid level, liquid volume, permittivity, and liquid flow

A system for measuring a capacitance of a first liquid, the system comprising:

• a first container configured to hold the first liquid;
• a reference container configured to hold a reference liquid, wherein there is a container separation distance between the first container and the reference container;
• a measurement circuit, comprising:
• a first sensor disposed on a first side of the first container, wherein there is a first separation distance between the first sensor and the first container, the first sensor comprising:
• a first electrode applied with a positive potential;
• a first composite substrate comprising a first template material, wherein the first template material comprises:
• a first plurality of insulating fibers;
• and
• a first plurality of carbon nanotubes bonded to the first insulating fibers forming a first nanotube coating on the first insulating fibers;
• wherein one edge of the first composite substrate is torn, wherein the first plurality of insulating fibers align along the tensile force and expand in an out-of-plane direction at the site of the tear;
• wherein the first electrode is coupled to the first nanotube coating at the site of the tear, such that an electrical signal passes through the plurality of junctions at the site of the tear;
• and wherein self-capacitance is formed between the single electrode and an environmental ground with a fringing field;
• and
• a reference sensor disposed on a first side of the reference container, wherein there is a second separation distance between the reference sensor and the reference container, the reference sensor comprising:
• a reference electrode;
• a capacitance to digital chip convertor configured to generate an excitation frequency;
• and
• a microprocessor configured to measure a capacitance change,
• wherein the measurement circuit is configured to measure a differential capacitance measurement between the first electrode and the reference electrode.

A liquid dispenser comprising:

• a first reservoir configured to hold a first liquid;
• a first sensor, disposed on a first side of the first reservoir, wherein there is a first separation distance between the first sensor and the first reservoir, and wherein the first sensor comprises:
• a first electrode applied with a positive potential;
• a first composite substrate comprising a first template material, wherein the first template material comprises:
• a first plurality of insulating fibers;
• and
• a first plurality of carbon nanotubes bonded to the first insulating fibers forming a first nanotube coating on the first insulating fibers;
• wherein one edge of the first composite substrate is torn, wherein the first plurality of insulating fibers align along the tensile force and expand in an out-of-plane direction at the site of the tear;
• wherein the first electrode is coupled to the first nanotube coating at the site of the tear, such that an electrical signal passes through the plurality of junctions at the site of the tear;
• and wherein self-capacitance is formed between the single electrode and an environmental ground with a fringing field;
• a first tubing fluidly coupled to the first reservoir;
• a second sensor coupled to the first tubing;
• a reference reservoir configured to hold a reference liquid;
• a first reference sensor, disposed on a first side of the reference reservoir, wherein there is a second separation distance between the first reference sensor and the reference reservoir,
• a reference tubing fluidly coupled to the reference reservoir;
• and
• a second reference sensor coupled to the reference tubing,
• wherein the first sensor is configured to measure a change in volume of the first liquid in the first reservoir, the second sensor is configured to measure an amount of first liquid that passes through the first tubing, the first reference sensor is configured to measure a change in volume of the reference liquid in the reference reservoir, and the second reference electrode is configured to measure an amount of reference liquid that passes through the reference tubing.