Optical E-Liquid Fill Sensing for Aerosol Cartridges

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Solution Overview

Problem

Aerosol-generating systems face challenges in determining the fill level of e-liquid in cartridges, as the liquid is not visible and excess heating can occur when depleted, leading to undesired compound generation and user inconvenience.

Innovation Solution

An aerosol-generating system with a light source and detector positioned adjacent to the e-liquid storage compartment, emitting light that is absorbed and detected to determine the fill level, allowing for accurate monitoring of e-liquid levels and preventing excessive heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a sensor is placed in contact with the e-liquid to monitor fill level, then measurement accuracy is improved, but the sensor may be degraded by the e-liquid and contamination occurs

Engineering Contradiction:
Improvefill level measurement accuracyVSAvoidsensor durability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent uses light as an intermediary substance to transfer information about the e-liquid fill level without the sensor needing to contact the liquid. The light source emits light through the cartridge wall, and the detector receives the light on the other side, with the e-liquid absorbing some light. This optical intermediary allows measurement while keeping the sensor components outside the e-liquid, preventing degradation and contamination.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the cartridge is made separate and removable from the device, then ease of replacement is improved, but the cartridge cannot have its own power supply and electrical components

Engineering Contradiction:
Improvecartridge replacement convenienceVSAvoidelectrical connection complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the power supply and control electronics from the removable cartridge and places them only in the main device. The cartridge contains only passive components (light source and detector that can be passively activated), allowing the cartridge to be easily replaced without complex electrical connections. The electrical complexity is taken out and centralized in the main device.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If the e-liquid volume in the cartridge is made small to reduce device size, then portability is improved, but accurate sensing becomes more difficult

Engineering Contradiction:
Improvecartridge sizeVSAvoidfill level detection accuracy
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent transitions from measuring e-liquid volume directly to measuring the optical properties (light absorption) of the e-liquid. By using optical measurement through the cartridge wall, the system can accurately detect fill levels in small volumes without being constrained by the physical size of the cartridge. This dimensional change from direct volume measurement to optical property measurement enables accurate sensing in compact form factors.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables users to anticipate refills, prevents exposure to undesired compounds, and reduces the risk of excessive heating by accurately monitoring e-liquid levels within the cartridge.

Implementation Method 1

The light source is positioned and oriented to emit light into the storage compartment of the cartridge. The light emitted from the light source is absorbed by the liquid composition.

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The detector is positioned and oriented to detect the light emitted from the light source. The detector comprises a light guide configured to direct the light within the storage compartment to a surface of the detector.

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP3886623B1Sensor for device aerosol-generating system
Publication Date: 2024.08.14 PHILIP MORRIS PRODUCTS SA
  • EP3886623B1 patent drawingFigure 1
  • EP3886623B1 patent drawingFigure 2
  • EP3886623B1 patent drawingFigure 3

AI summary

An aerosol-generating system (1) includes a cartridge (100), an aerosol-generating device (300) configured to receive the cartridge, a light source (160), and a detector (165). The cartridge includes a storage compartment (103) configured to contain a liquid composition comprising an aerosol-forming substrate (131). The aerosol-generating device comprises a power supply (310) and control electronics (320) operably coupled to the power supply. The light source is operably coupled to the control electronics and positioned and oriented to emit light into the storage compartment of the cartridge. The light emitted from the light source is absorbed by the liquid composition. The detector is operably coupled to the control electronics and positioned and oriented to detect light emitted from the light source. The light source and the detector are both located adjacent to a same side of the storage compartment and a surface of the storage compartment opposite the light source is configured to absorb light emitted into the storage compartment from the light source.