Capacitive Solid Fraction Sensor for Inline Pharmaceutical Porosity
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Solution Overview
Problem
Current methods for determining the porosity of pharmaceutical intermediates and final dosage forms are inefficient for inline/online automated measurements, particularly in roller compaction processes, as they require off-line analysis, are prone to errors, and lack sensitivity and accuracy for real-time process control.
Innovation Solution
A solid fraction sensor using a capacitance-based system with conductor elements and an energy source to generate an electric field, allowing for the determination of solid fraction by measuring capacitance changes and calibrating with reference samples, enabling accurate and fast inline/online measurements without electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If off-line analysis methods are used to determine porosity, then measurement accuracy can be achieved, but real-time process control is not possible
Solution Approach 1:
The patent replaces mechanical/off-line measurement systems with a capacitive sensing system that uses electrical fields to measure solid fraction in real-time. The capacitive sensor detects changes in capacitance caused by variations in solid fraction without physical contact, enabling online process control while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an electrical field as an intermediary between the sensor and the pharmaceutical sample. The capacitive sensor measures solid fraction through the electrical field's interaction with the dielectric properties of the sample, allowing non-contact, real-time measurement that bridges the gap between offline accuracy and online speed.
2Extent of automation
If NIR spectroscopy is used for porosity measurement, then process analytical technology capability is provided, but the measurement is indirect and requires complex multivariate calibration
Solution Approach 1:
The patent replaces NIR spectroscopy with a capacitive sensing system that directly measures solid fraction through electrical field interactions. This substitution eliminates the need for complex multivariate calibration while maintaining PAT capability and automation, as the capacitive measurement provides a direct relationship between capacitance change and solid fraction.
Solution Approach 2:
The patent changes the measurement parameter from optical properties (NIR spectroscopy) to electrical properties (capacitance). This parameter change simplifies the measurement physics, creating a more direct relationship between the measured signal and solid fraction, thereby reducing calibration complexity while maintaining automated process control capability.
3Ease of manufacture
If thermal imaging is used for ribbon porosity analysis, then a low-cost solution is provided, but it requires sufficient ribbon quality and careful environmental consideration
Solution Approach 1:
The patent replaces thermal imaging with capacitive sensing, which uses electrical fields instead of thermal radiation detection. This substitution improves reliability by making the measurement independent of ribbon quality and environmental thermal conditions, while maintaining cost-effectiveness through the use of simple capacitive sensor geometry.
Solution Approach 2:
The patent changes the measurement parameter from thermal radiation to electrical capacitance. This parameter change fundamentally improves measurement reliability by eliminating sensitivity to ribbon quality variations and environmental thermal effects, while the capacitive sensor design keeps the system cost-effective.
4Ease of operation
If capacitive sensors are used to evaluate mass, then simple measurement is achieved, but solid fraction determination is not possible
Solution Approach 1:
The patent changes the measurement interpretation from mass (total capacitance) to solid fraction (capacitance change). By measuring the change in capacitance as the sample passes through the sensor and using differential measurements, the system extracts solid fraction information while maintaining the simplicity of capacitive sensing.
Solution Approach 2:
The patent uses feedback through calibration with reference samples of known solid fraction. The system measures capacitance changes and compares them against calibrated values to determine solid fraction, providing a simple yet accurate measurement process that transforms basic capacitive sensing into precise solid fraction 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
The solution provides sensitive and accurate measurements of solid fraction with less than 3% absolute deviation, suitable for a broad range of solid fractions, and is robust against product lamination and fractionation, facilitating real-time process control in pharmaceutical manufacturing.
Implementation Method 1
an energy source arranged to generate an electric field in the operation space by means of the first conductor element and the second conductor element
Implementation Method 2
determining a capacitance between the first and second conductor element with the target pharmaceutical sample located in the operation space
Implementation Method 3
converting the determined capacitance together with information about a composition of a reference pharmaceutical sample having the essentially same dielectric properties as the target pharmaceutical sample
Data Source
Figure 1a~2
Figure 3a~3b
Figure 3c~4
AI summary
For the use of a solid fraction sensor (17) to evaluate a solid fraction of a target pharmaceutical sample (4, 10) the solid fraction sensor (17) has a first conductor element (5), a second conductor element (7), an operation space (15) and an energy source (13) arranged to generate an electric field in the operation space (15) by means of the first conductor element (5) and the second conductor element (7), comprising positioning the target pharmaceutical sample (4, 10) in the operation space (15) of the solid fraction sensor (17), determining a capacitance between the first and second conductor element (5, 7) with the target pharmaceutical sample (4, 10) located in the operation space (15), and converting the determined capacitance together with information about a composition of a reference pharmaceutical sample having the essentially same dielectric properties as the target pharmaceutical sample (4, 10) and about a thickness of the reference pharmaceutical sample (4, 10) into a solid fraction of the target pharmaceutical sample (4, 10).