RF Hydration Sensor Wireless Power and Thermal Sensing

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Solution Overview

Problem

Current wireless sensing technologies face challenges in accurately measuring thermal properties of objects, particularly in determining hydration levels, due to limitations in power transfer and spatial resolution.

Innovation Solution

The development of RF hydration sensors with a substrate, antenna, RF circuit, thermal source, and sensing element, which wirelessly receive power, transform it, and use the thermal source to sense temperature variations, allowing for the determination of hydration levels based on thermal property changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If wireless power transfer is used to power the thermal source, then the device can operate wirelessly, but the power transfer efficiency and spatial resolution are limited

Engineering Contradiction:
Improvewireless operationVSAvoidpower transfer efficiency
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The patent introduces an RF circuit as an intermediary component that receives wireless power and converts it to a form suitable for heating the thermal source. This intermediary conversion stage enables wireless operation while managing power transfer efficiency through controlled electromagnetic field interaction.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct electrical connections with wireless RF power transfer, substituting mechanical/electrical coupling with electromagnetic field-based energy transfer. This enables wireless operation of the thermal source while the RF circuit manages the conversion and efficiency aspects.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a thermal source is used to measure thermal properties, then hydration level can be determined, but the measurement accuracy is affected by power transfer limitations

Engineering Contradiction:
Improvehydration level measurementVSAvoidpower transfer efficiency
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent employs a feedback mechanism where the sensing element detects temperature changes caused by the thermal source, and this information is processed to determine hydration level. The system uses the thermal response feedback to compensate for power transfer variations and improve measurement accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent measures hydration level by detecting changes in thermal parameters (temperature, thermal conductivity) rather than directly measuring power transfer efficiency. By monitoring thermal property changes in the target material, the system achieves accurate hydration measurement despite wireless power transfer limitations.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the RF circuit transforms power from one form to another, then the thermal source can be powered wirelessly, but the device complexity increases

Engineering Contradiction:
Improvewireless power deliveryVSAvoidpower transformation circuit
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The RF circuit performs multiple functions: receiving wireless power, converting it to appropriate form, regulating power delivery to the thermal source, and enabling wireless communication. This multi-functionality reduces the need for separate components and manages the complexity through integrated design.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the power reception, power conversion, and thermal source control into a single integrated RF circuit module. This merging of functions reduces overall device complexity compared to having separate wireless power receiver and thermal control systems.

Inventive Principle:
Principle #5Merging (Combining)

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 accurate and efficient hydration level monitoring by transforming received power and using thermal property changes to generate hydration indicators, improving the accuracy and efficiency of wireless sensing systems.

Implementation Method 1

a thermal source electrically coupled to the RF circuit for changing a thermal condition of a target area

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a sensing element thermally coupled to the thermal source for sensing a temperature of the thermal source

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the RF hydration sensor wirelessly receives a first power having a first form from a transceiver

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3215834B1Wireless sensing devices and method for detecting hydration
Publication Date: 2023.08.16 3M INNOVATIVE PROPERTIES CO
  • EP3215834B1 patent drawingFigure 1A
  • EP3215834B1 patent drawingFigure 1B
  • EP3215834B1 patent drawingFigure 1C

AI summary

At least some aspects of the present disclosure feature an RF hydration sensor in an assembly, comprises a substrate; an antenna disposed on the substrate; an RF circuit electrically coupled to the antenna; a thermal source electrically coupled to the RF circuit for changing a thermal condition of a target area; and a sensing element thermally coupled to the thermal source for sensing a temperature of the thermal source. The RF hydration sensor wirelessly receives a power from a remote transceiver and provides at least part of the power to the thermal source.