Multi-Wavelength Absorbance Sensing for Online Microalgae Biomass
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Solution Overview
Problem
Existing biomass concentration measurement methods for microalgae cultures are offline, labor-intensive, and lack scalability and adaptability, leading to suboptimal reactor operation and reduced productivity due to the inability to monitor biomass concentration and growth rate in real-time.
Innovation Solution
A device with a culture sampling pump, filtration system, and absorbance sensor that measures biomass concentration online using a wide range of wavelengths, coupled with a data acquisition system for continuous monitoring and optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline measurement methods (dry weight determination) are used, then measurement accuracy is maintained, but productivity and real-time monitoring capability deteriorate due to long processing times and labor intensity
Solution Approach 1:
The patent replaces mechanical/chemical offline measurement methods (filtration, drying, weighing) with an optical measurement system that uses light absorption at multiple wavelengths to determine biomass concentration. This substitution enables real-time, automated measurements without the time-consuming laboratory procedures, thus maintaining measurement accuracy while dramatically improving productivity and enabling continuous monitoring for optimal reactor operation
Solution Approach 2:
The patent introduces an optical intermediary (light at specific wavelengths) to measure biomass concentration indirectly through light absorption properties. This intermediary approach allows non-intrusive, continuous measurement of the culture without disrupting the photosynthetic process or requiring sample removal for laboratory analysis, thereby maintaining both measurement precision and reactor productivity
2Device complexity
If single-wavelength turbidity sensors are used, then device complexity is reduced, but adaptability and measurement reliability deteriorate due to inability to differentiate between different types of solids
Solution Approach 1:
The patent segments the optical measurement into multiple discrete wavelength channels (at least three wavelengths in the 400-700 nm range). Each wavelength provides specific information about the culture composition, and by combining these segmented measurements, the system can differentiate between microalgae cells, other solids, and culture media components, achieving both adaptability and reliable measurement without excessive complexity
Solution Approach 2:
The patent exploits the wavelength-dependent light absorption characteristics (optical color properties) of different substances in the culture. By measuring absorption at multiple specific wavelengths, the system can distinguish microalgae biomass from other solids based on their different spectral signatures, thereby achieving adaptability and differentiation capability while maintaining reasonable device complexity
3Adaptability or versatility
If multiple wavelength absorption sensors are used, then adaptability and measurement reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent designs a multi-wavelength absorption sensor system where a single device performs multiple functions: measuring biomass concentration, differentiating microalgae from other solids, and monitoring culture composition changes. This universal approach consolidates what would otherwise require multiple separate measurement systems, achieving high adaptability and reliability while controlling device complexity through integrated design
Solution Approach 2:
The patent varies the optical parameter (wavelength) to achieve different measurement objectives. By selecting specific wavelengths that correspond to absorption characteristics of microalgae pigments and other culture components, the system achieves high adaptability and differentiation capability. The use of discrete wavelength points rather than continuous spectral analysis simplifies the device complexity while maintaining measurement reliability
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 continuous, cost-effective, and scalable biomass concentration measurement, enhancing reactor productivity by over 35% through real-time data integration, reducing maintenance needs and improving operational efficiency.
Implementation Method 1
an absorption sensor that considers a wide range of wavelengths so it can differentiate between different types of solids, especially microalgae cells
Data Source
Figure 1
Figure 2
AI summary
The device comprises an absorbance sensor (3), which works with three wavelengths between 400 and 700 nm, intended to emit and collect light reflected from the culture (1), and a sampling pump (2) to the circulation of the culture (1) through the absorbance sensor (3). For its part, the procedure includes the steps of illuminating the culture (1) with light with three different wavelengths, between 400 and 700 nm, collecting a light reflected from the crop (1), and obtaining the RGB colour coordinates. of the reflected light, obtain the absorbance from the RGB coordinates, perform a regression with absorbance and reference concentration data, and obtain the biomass concentration in the culture (1).