Permeable Leaf Chamber for Continuous Gas Exchange Measurement

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Solution Overview

Problem

Conventional methods for measuring plant biological information, such as transpiration rate and carbon dioxide assimilation rate, face challenges in continuous measurement due to water vapor saturation and carbon dioxide depletion within sealed or ventilated chambers, requiring complex adjustments and flow rate calculations.

Innovation Solution

A biological device using a permeable membrane with resistance to water vapor or carbon dioxide to create a space for continuous measurement, allowing sensors to measure concentration differences without air flow control, maintaining open air exchange.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealed chamber is used to measure plant biological information, then measurement can be performed, but water vapor saturation and carbon dioxide depletion occur over time making continuous measurement difficult

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidcontinuous measurement duration
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies porous materials by using a permeable membrane (such as a semipermeable membrane or porous polymer) as the chamber wall that allows selective passage of water vapor and carbon dioxide. This membrane maintains concentration gradients necessary for measurement while preventing complete saturation or depletion, enabling continuous long-term measurement of transpiration rate and carbon dioxide assimilation rate without requiring chamber ventilation or atmosphere adjustment.

Inventive Principle:
Principle #31Porous materials

2Duration of action of stationary object

If a ventilated chamber is used to prevent saturation, then continuous measurement is possible, but complex air flow control devices and flow rate calculations are required

Engineering Contradiction:
Improvecontinuous measurement capabilityVSAvoidair flow control complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent extracts the air flow control system entirely from the measurement apparatus. Instead of using ventilated chambers with fans, valves, and flow meters, the invention uses a passive permeable membrane chamber that naturally maintains gas exchange through the membrane. This eliminates complex air flow control devices and the need for flow rate calculations, while still enabling continuous measurement by preventing water vapor saturation and carbon dioxide depletion through the membrane's selective permeability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If human visual inspection is used to evaluate plant biological information, then no special equipment is needed, but accurate evaluation is difficult for inexperienced producers

Engineering Contradiction:
Improvesimplicity of equipmentVSAvoidbiological information evaluation accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical/optical system of human visual inspection with a sensor-based measurement system. The permeable membrane chamber coupled with sensors for detecting water vapor concentration and carbon dioxide concentration provides objective, quantitative measurements of transpiration rate and carbon dioxide assimilation rate. This substitution transforms subjective visual evaluation into precise instrumented measurement that is accessible to producers regardless of experience level.

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

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 easy and continuous measurement of plant biological information by avoiding saturation or depletion, eliminating the need for air flow rate calculations and gas flow control devices.

Implementation Method 1

at least a part of the wall constituting the container is constituted by a permeable membrane having permeation resistance to water vapor or carbon dioxide

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 2

the permeable membrane having permeation resistance to water vapor or carbon dioxide

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP4659564A1Biological information measuring instrument and biological information measuring method
Publication Date: 2025.12.10 HIROSHIMA UNIVERSITY
  • EP4659564A1 patent drawingFigure 1~2
  • EP4659564A1 patent drawingFigure 3~4
  • EP4659564A1 patent drawingFigure 5~6

AI summary

This biological information measuring instrument is characterized by comprising: a receptacle for covering at least a section of a plant leaf; and a sensor for measuring the concentration of water vapor and/or carbon dioxide on the inside and the outside of the receptacle. At least a section of the walls that constitute the receptacle is characterized by being formed of a permeable film having permeation resistance with respect to water vapor and carbon dioxide.