Capacitive Packaging Thickness Measurement for Permeation Rate
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Solution Overview
Problem
Current methods for determining the permeation rate of packaging materials, especially high-barrier films, are either too slow, lack accuracy, or are not suitable for quick in-process control, making it difficult to ensure product stability for sensitive pharmaceuticals.
Innovation Solution
A capacitive measurement method that calculates the average layer thickness of packaging materials using the ratio of area to thickness, leveraging Fick's diffusion equation and Henry's law, allowing for rapid and accurate determination of permeation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional permeation rate determination methods are used, then measurement accuracy is maintained, but measurement time becomes excessively long and productivity decreases
Solution Approach 1:
The patent replaces conventional gravimetric measurement methods with a capacitive measurement system. Instead of mechanically weighing the packaging material before and after moisture exposure, the system uses electrical capacitance measurements to detect changes in the packaging structure caused by moisture permeation. This substitution of measurement principle dramatically reduces measurement time while maintaining accuracy.
Solution Approach 2:
The patent changes the measurement parameter from mass change (gravimetric method) to capacitance change (electrical property). By measuring the capacitance of the packaging material, which changes in response to moisture content and layer thickness variations, the system achieves rapid permeation rate determination without the time-consuming weight measurements required by conventional methods.
2Reliability
If conventional permeation rate determination methods are used, then comprehensive data is obtained, but device complexity and operational difficulty increase
Solution Approach 1:
The patent extracts and isolates the specific measurement function needed for permeation rate determination from the complex conventional testing systems. By focusing solely on capacitance measurement rather than comprehensive environmental chamber testing, the system achieves reliable permeation rate data with a simpler, more focused measurement device.
Solution Approach 2:
The patent simplifies the measurement approach by changing from multi-parameter gravimetric analysis to single-parameter capacitance measurement. This parameter change reduces device complexity while maintaining the reliability needed for product stability assurance, as capacitance changes directly correlate with moisture permeation effects.
3Measurement precision
If average layer thickness is not accurately determined, then permeation rate calculation is compromised, but measurement time increases
Solution Approach 1:
The patent replaces physical measurement methods for layer thickness determination with electrical capacitance measurement. The capacitance of the packaging material is directly related to its layer thickness and dielectric properties, allowing rapid calculation of thickness without time-consuming physical measurements.
Solution Approach 2:
The patent uses capacitance as a proxy parameter for layer thickness measurement. By measuring the electrical capacitance of the packaging material, the system can calculate layer thickness based on the relationship between capacitance, dielectric constant, and physical dimensions, achieving rapid and accurate thickness determination.
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
This method provides a fast, simple, and reliable means to determine the permeation rate, enabling effective in-process control and packaging development for ensuring product stability, particularly for sensitive pharmaceuticals.
Implementation Method 1
determining the average layer thickness of a packaging material (2) by means of a capacitive measurement of the object to be examined (1) with a known material-specific relative permittivity
Implementation Method 2
with a known material-specific relative permittivity and a known area
Implementation Method 3
Fick's diffusion equation applies here, which can be written as follows for a linear system with spatial coordinates x and a constant diffusion coefficient D
Implementation Method 4
Assuming that the diffusion coefficient is constant and the sorption isotherm of the material is linear, Henry's law applies: where is the constant of proportionality
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An apparatus for determining the average layer thickness ℓ of a flat packaging material for pharmaceutical packagings, in particular blisters and/or bottles, by means of a capacitive determination during which the opposite outer surfaces of the packaging material are provided with electrodes.