Linear Transimpedance Amplifier for Optical Fluid Analysis
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Solution Overview
Problem
Existing optical measurement devices for fluid analysis in biotechnology face challenges such as limited dynamic range, high latency, and interference from uncorrectable disturbances, particularly when measuring small photocurrents with high accuracy and reproducibility, and require continuous, uninterrupted monitoring.
Innovation Solution
A device utilizing a linear transimpedance amplifier with reed relays for range switching and effective filtering, combined with a shielded housing and galvanic isolation, to minimize interference and ensure continuous, low-latency measurement of photocurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temporal modulation of incident optical intensity is used to separate slowly changing disturbances, then measurement precision is improved, but device complexity and response time worsen
Solution Approach 1:
The patent extracts and removes the temporal modulation component from the measurement system. Instead of modulating the light source and using lock-in amplification, the invention directly measures the DC photocurrent signal, eliminating the need for modulation/demodulation circuitry and reducing device complexity while maintaining measurement precision through direct amplification of the photocurrent
Solution Approach 2:
The patent eliminates periodic modulation of the light source and instead uses continuous illumination with DC coupling to the amplifier. This removes the need for synchronous detection and lock-in amplification circuits, simplifying the device while achieving comparable disturbance rejection through proper filtering and amplification of the continuous signal
2Measurement precision
If temporal modulation with high dynamics is used to follow rapid changes, then measurement precision is improved, but response time worsens
Solution Approach 1:
The patent implements continuous measurement without temporal modulation by directly amplifying the DC photocurrent signal. This continuous action allows the system to respond immediately to changes in the measured variable without the delays inherent in modulation cycles, filtering, and demodulation processes, achieving both high precision and fast response times
3Measurement precision
If dual-beam solutions with temporary interaction are used for normalization, then measurement precision is improved, but device complexity and response time worsen
Solution Approach 1:
The patent extracts and removes the dual-beam normalization mechanism from the system. Instead of temporarily directing light to a reference detector for normalization, the invention uses a single beam with direct DC amplification and software-based normalization, eliminating the complex beam switching and temporary interaction mechanisms while maintaining measurement accuracy and improving response time
4Measurement precision
If logarithmic amplifiers are used to convert photocurrents, then measurement precision over wide ranges is improved, but manufacturing precision and reliability worsen
Solution Approach 1:
The patent replaces complex logarithmic amplifiers with simple linear transimpedance amplifiers followed by software-based logarithmic conversion. This approach uses readily available, easily manufactured linear amplifier circuits that are more reliable and easier to manufacture with high precision, while achieving the same measurement precision over wide dynamic ranges through digital processing
Solution Approach 2:
The patent substitutes hardware-based logarithmic amplification with a combination of linear amplification and software-based logarithmic conversion. This replacement of the complex analog logarithmic function with digital processing improves manufacturing precision, reliability, and ease of calibration while maintaining measurement precision across wide dynamic ranges
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, jump-free monitoring with low latency, allowing for precise control of process parameters and seamless process documentation, even under dynamic conditions, with a wide measurement dynamic range and high interference attenuation.
Implementation Method 1
The light beam leaves the measuring volume and strikes a silicon photodiode, which generates a photocurrent approximately proportional to the light intensity
Implementation Method 2
a linear transimpedance amplifier for detecting and amplifying the signals, in particular the photocurrents
Implementation Method 3
The light passes through the medium and is attenuated by absorption and/or scattering
Implementation Method 4
The light passes through the medium and is attenuated by absorption and/or scattering
Data Source
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AI summary
A device and a method for optically determining a substance concentration of a fluid are proposed, comprising a measuring amplifier for amplifying measured photocurrents, wherein the measuring amplifier has at least one linear transimpedance amplifier for detecting and amplifying the photocurrents.