pH Measurement via Dual-Wavelength Absorbance Ratio
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Solution Overview
Problem
Current methods for measuring pH in cell culture solutions, such as visual checks of phenol red color change or immersion of pH electrodes, are prone to errors and contamination risks.
Innovation Solution
A method and apparatus using visible light absorption by phenol red with two absorption peaks to calculate pH, where light beams of specific wavelengths are emitted and received, and the solution is pulsed to obtain absorbance ratios, allowing pH calculation without zero level correction at wavelengths with minimal absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If visual check of phenol red color change is used, then pH measurement can be performed, but measurement precision deteriorates due to erroneous checks
Solution Approach 1:
The patent replaces the visual inspection method (mechanical/optical observation) with an automated spectrophotometer-based measurement system. The spectrophotometer objectively measures absorbance at multiple wavelengths, eliminating subjective visual assessment and its associated errors while maintaining ease of operation through automated data processing.
Solution Approach 2:
The patent measures pH by detecting changes in absorbance parameters at multiple specific wavelengths (430-440 nm and 560-570 nm) rather than relying on subjective color interpretation. By quantifying absorbance at these specific wavelengths and calculating ratios, the system achieves precise pH measurement while keeping the operation simple through automated parameter analysis.
2Measurement precision
If pH electrodes are immersed in cell culture solution, then measurement precision is improved, but object-generated harmful factors worsen due to contamination from insufficient sterilization
Solution Approach 1:
The patent introduces an intermediary substance - phenol red indicator - that mediates the pH measurement process. Instead of directly contacting the cell culture solution with electrodes, the system measures the absorbance characteristics of the indicator in the solution, eliminating the contamination risk associated with electrode immersion while maintaining measurement precision.
Solution Approach 2:
The patent replaces the physical immersion of pH electrodes (mechanical contact) with optical measurement using a spectrophotometer. This substitution eliminates the direct contact between measurement devices and the cell culture solution, thereby preventing contamination while preserving accurate pH measurement capability through absorbance spectroscopy.
3Object-affected harmful factors
If phenol red is contained at low concentration to avoid harm to cells, then cell safety is improved, but measurement precision deteriorates due to weak absorption signals
Solution Approach 1:
The patent measures pH in another dimension by detecting absorbance at multiple specific wavelengths (430-440 nm and 560-570 nm) simultaneously. By measuring absorbance ratios at these different wavelengths rather than relying on single-wavelength intensity, the system maintains sensitivity for low concentrations while improving measurement precision through ratio-based calculations that compensate for concentration variations.
Solution Approach 2:
The patent changes the measurement parameter from absolute absorbance intensity to absorbance ratio at multiple wavelengths. This parameter transformation allows accurate pH measurement even at low indicator concentrations, as the ratio of absorbances at different wavelengths provides a concentration-independent measure that maintains precision while using minimal phenol red to protect cells.
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 approach provides accurate pH measurement in cell culture solutions without the need for zero level correction, reducing errors and contamination risks, and is suitable for use in sterile environments.
Implementation Method 1
the pH is measured based on absorption of visible light in a cell culture solution that includes: a cell culture medium; serum; and an indicator having two or more kinds of absorption peaks in the wavelength region of visible light
Data Source
AI summary
A method of measuring a pH of a solution includes: emitting light beams of two wavelengths from one side of a measuring region of a solution into which an indicator is mixed, while pulsating the solution in the measuring region; receiving at least one of transmitted light beams and reflected light beams of the emitted light beams on the other side of the measuring region, while pulsating the solution in the measuring region; obtaining absorbances of the two wavelengths based on the received at least one of the transmitted light beams and the reflected light beams; obtaining an absorbance ratio from the obtained absorbances; and calculating a pH value of the solution based on the obtained absorbance ratio and an absorbance ratio/pH value correspondence database which is previously stored.