Plasmonic Optical Sensing with Dual-LED Drift Compensation
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Solution Overview
Problem
Optical sensors face challenges in maintaining accuracy, stability, and robustness due to external factors like temperature, humidity, and ambient light, while conventional light sources like lasers are expensive and have a large footprint, necessitating a cost-effective solution.
Innovation Solution
An optical measurement device utilizing a plasmonic sensing element with controlled illumination by two light sources to alternately illuminate light sensors, compensating for environmental influences and reducing long-term drift, featuring a housing to protect components and using LEDs for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lasers are used as light sources for optical measurements, then stability of emitted light (intensity and wavelength) is improved, but cost and device footprint increase
Solution Approach 1:
The patent replaces expensive, stable laser sources with cheaper, less stable LED light sources. This substitution accepts the shorter operational life and lower inherent stability of LEDs while achieving cost reduction and miniaturization. The system compensates for LED instability through differential measurement techniques.
Solution Approach 2:
The patent changes the operating parameters of the light sources by using multiple LEDs with different characteristics (intensity, wavelength) and dynamically adjusting their operation. The system varies illumination parameters to achieve stable measurements despite individual LED drift, transforming the approach from relying on single-source stability to managing multiple variable sources.
2Measurement precision
If conventional optical sensors are used, then measurement capability is achieved, but accuracy is reduced due to environmental perturbations (temperature, humidity, ambient light)
Solution Approach 1:
The patent extracts and separates the measurement of environmental factors from the primary measurement function. By using a second light sensor dedicated to detecting ambient light and environmental conditions, the system isolates these harmful factors into a separate measurement channel that can be compensated for in the final calculation.
Solution Approach 2:
The patent implements feedback mechanisms where the signals from the second light sensor (detecting environmental perturbations) are fed back into the measurement system to compensate for their effects. The control circuit uses this feedback information to adjust and correct the primary measurement, maintaining accuracy despite environmental changes.
3Reliability
If dual light source illumination is implemented, then compensation for environmental factors is improved, but device complexity increases
Solution Approach 1:
The patent makes the second light sensor serve multiple functions: it detects ambient light conditions, monitors environmental perturbations, and provides reference signals for compensation. This multi-functionality reduces the need for additional dedicated components, offsetting the complexity increase from adding the second light source and sensor.
Solution Approach 2:
The patent merges the functions of environmental monitoring and primary measurement into a unified system where both light sensors process information that contributes to the final compensated measurement. The control circuit combines signals from both sensors to achieve accurate measurements, merging what could be separate functions into an integrated approach.
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 device provides robust and stable readout of ambient properties, improving sensitivity and accuracy by compensating for environmental factors, allowing small sample size measurements with reduced influence from external factors.
Implementation Method 1
the sensing section consists of a metal-like thin film, particle, or assembly of particles. Such a sensing section can be capable of supporting travelling electromagnetic waves, usually referred to as surface plasmon polaritons, at an interface between the thin film or particles and the ambient environment.
Data Source
AI summary
The present invention relates to a method and device for determining a property of an ambient environment. The device comprises a plasmonic sensing element; a first light source for illuminating a first and a second light sensor, the first sensor via the plasmonic sensing element; a second light source for illuminating the light sensors; circuitry for executing: a control function controlling light sources, a function receiving a measurement from the first sensor, and a first signal from the second sensor, a function receiving a reference from the first sensor, and a second signal from the second sensor, a function determining the property by comparing the measurement and reference signals, and the control function further controlling light sources such that a relation of intensities of light emitted by the light sources is constant over time.