Optical Analyte Detection Phase-Sensitive Signal Processing
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Solution Overview
Problem
Current analyte detection systems for drugs of abuse in oral fluid face challenges such as delayed results due to laboratory processing, and limitations in signal-to-noise ratio in optical detection methods.
Innovation Solution
The development of phase-sensitive signal detection methods and apparatuses that utilize a high-frequency pulsed excitation laser with dynamically adjusted peak power and duty cycle, combined with a matching filter in post-processing, to enhance the signal-to-noise ratio. Additionally, the use of a non-scanning optical cartridge reader with a photonic chip and multimode optical transceivers reduces the need for optical alignment and allows for precise determination of the dilution factor in saliva samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical detection with single pulse excitation is used, then the system is simple to operate, but the signal-to-noise ratio is insufficient
Solution Approach 1:
The patent applies periodic action by using high-frequency pulsed excitation (e.g., 1 kHz or higher) instead of single pulse excitation. The laser is modulated at high frequencies to create periodic excitation cycles, allowing the system to accumulate signal information over multiple cycles while maintaining a simple operational interface. This periodic modulation enables phase-sensitive detection to distinguish signal from noise.
Solution Approach 2:
The patent implements feedback through phase-sensitive detection that compares the phase of the excitation signal with the detected fluorescence signal. By using a reference signal from the modulated laser and comparing it with the detected signal phase, the system provides feedback to maximize signal extraction while rejecting out-of-phase noise components, thereby improving signal-to-noise ratio without requiring complex manual adjustments.
2Productivity
If scanning optical head is used to read the cartridge, then the detection scheme is well-established, but the measurement time is extended
Solution Approach 1:
The patent replaces the mechanical scanning system with a stationary optical detection system. Instead of physically moving the optical head across the cartridge, the system uses a fixed optical path with modulated excitation and phase-sensitive detection. This substitution eliminates mechanical scanning constraints and enables simultaneous or near-simultaneous detection, dramatically reducing measurement time while maintaining detection accuracy.
3Measurement precision
If standard lock-in detection is used with flat noise spectrum, then the detection method is simple, but no signal-to-noise improvement is achieved
Solution Approach 1:
The patent overcomes the limitation of standard lock-in detection by using high-frequency periodic modulation (1 kHz or higher) of the excitation laser. This high-frequency periodic action shifts the signal spectrum away from the flat noise region, allowing phase-sensitive detection to effectively filter noise. The periodic modulation creates a frequency domain separation between signal and noise that enables genuine signal-to-noise improvement.
Solution Approach 2:
The patent changes the operational parameters by using high-frequency modulation (1 kHz or higher) instead of conventional low-frequency or DC excitation. This parameter change transforms the detection regime, enabling the system to operate in a frequency range where phase-sensitive detection can effectively distinguish signal from noise, thereby achieving signal-to-noise improvement with a relatively simple detection method.
4Measurement precision
If optical alignment is required for cartridge reading, then the optical system can be precise, but the device complexity increases
Solution Approach 1:
The patent applies self-service through the use of waveguide-based optical paths that inherently guide and align the excitation and detection beams. The waveguide structure automatically performs the alignment function, eliminating the need for manual or automated optical adjustment mechanisms. The system self-aligns through the physical constraints of the waveguide geometry, maintaining optical precision while reducing device complexity.
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 significantly improves the signal-to-noise ratio by 1-2 orders of magnitude, enables rapid and accurate analyte detection at the point of testing, and provides a precise method for determining the dilution factor in saliva samples, addressing the limitations of existing systems.
Implementation Method 1
exciting the laser to illuminate the photonic chip; detecting an optical signal from the photonic chip
Implementation Method 2
demodulating the output signal using the modulated signal, wherein the demodulated signal is proportion to the cosine of the phase difference between the modulated signal and the output signal
Data Source
AI summary
Analyte collection and testing systems and methods, and more particularly to testing systems and methods that achieve significant improvements in the detection of fluorescence signals in the reader by modulating the applied optical excitation. Also described herein are optical detection apparatuses and methods for removable photonic chips that do not require translation for calibration when coupling the photonics chip with the sensing system. Also described herein are methods and apparatuses for accurately calibrating a dilution factor when reading from a photonics chip.