VCO Quantizer Modulator for Weak Fluorescence Current Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current biosensors face challenges in accurately measuring weak fluorescent signals from biomaterials due to interference from external light, which generates larger and longer-lasting currents, making it difficult to distinguish the desired signal from the photodiode's output.
Innovation Solution
A low power modulator with a VCO quantizer is developed, incorporating an integrator to convert input current to voltage, a quantizer to digital information, a filter unit to filter digital information, a DAC to convert back to feedback current, and a controller to calculate digital information based on the difference between input and feedback currents, with PWM adjusting the DAC bit to 1 bit, effectively isolating the desired signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical techniques are used to collect fluorescence light for measurement, then measurement capability is improved, but system cost and complexity increase significantly
Solution Approach 1:
The patent replaces the optical measurement system (microscope) with an electrical measurement system. A photodiode converts fluorescence light into electrical current signals, which are then processed by electronic circuits including transimpedance amplifiers and modulators. This substitution eliminates the need for complex optical components while achieving equivalent measurement capability.
Solution Approach 2:
The patent introduces a photodiode as an intermediary device that converts optical signals (fluorescence light) into electrical signals. This intermediary enables the use of electronic processing techniques instead of direct optical measurement, simplifying the overall system while maintaining measurement precision.
2Measurement precision
If photodiodes are used to detect light signals, then electrical signal measurement is enabled, but external light interference generates large currents that overwhelm the weak fluorescent signal
Solution Approach 1:
The patent employs periodic modulation by applying an AC test voltage to the photodiode, which modulates the current at a specific frequency. The modulation technique allows the system to distinguish between the modulated fluorescent signal and the unmodulated external light interference, effectively filtering out the harmful external light currents.
Solution Approach 2:
The patent uses feedback circuits including transimpedance amplifiers and modulators that continuously monitor and process the photodiode current. The feedback mechanism enables real-time signal processing to extract the weak fluorescent signal while rejecting the larger external light interference through differential measurement and frequency-based filtering.
3Device complexity
If conventional current measurement methods are used for photodiode output, then simple circuit design is maintained, but ability to distinguish desired signal from external light current is lost
Solution Approach 1:
The patent introduces periodic modulation using AC test voltages applied to the photodiode. This modulation technique embeds the desired fluorescent signal at a specific frequency, allowing the system to distinguish it from external light interference through frequency-selective processing, while maintaining relatively simple circuit implementation.
Solution Approach 2:
The patent changes the measurement parameter from direct DC current measurement to frequency-domain analysis. By modulating the photodiode with AC signals and analyzing the frequency characteristics of the output current, the system achieves signal discrimination capability while keeping the circuit design relatively simple using standard electronic components.
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 solution enables accurate measurement of both electrical and fluorescent signals across a wide range of input currents, reducing power consumption and system complexity, allowing for more efficient measurement of low power systems and devices with improved signal recognition and reduced noise.
Implementation Method 1
biosensors for measuring currents of photodiodes
Data Source
AI summary
Disclosed is a low power modulator with a VCO quantizer. The low power modulator with the VCO quantizer may include an integrator converting an input current to a voltage, a quantizer converting the converted voltage to digital information, a filter unit filtering the converted digital information, a DAC converting the filtered digital information into a feedback current, and a controller calculating the digital information output based on a difference value between the input current and the feedback current for each sampling time.