Time-of-Flight Camera for Luminescence Lifetime Separation
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Solution Overview
Problem
Existing methods for measuring fluorescence lifetimes in microscopy and medical diagnostics struggle to accurately distinguish between superimposed luminescence responses from multiple fluorophores, often resulting in the determination of only an average fluorescence lifetime.
Innovation Solution
A device and method utilizing a time-of-flight camera with a periodic modulation signal and semiconductor-based radiation sources for phase-sensitive detection, allowing for the calculation of individual luminescence lifetimes by varying pulse durations and considering phase positions, enabling the separation of superimposed luminescence responses with different lifetimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-domain methods with pulsed lasers and time-correlated single photon counting are used, then fluorescence lifetime measurement capability is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex time-correlated single photon counting electronics with a camera-based detection system. Instead of using sophisticated time-domain electronics to measure fluorescence decay, the invention uses a camera to capture spatially and temporally resolved fluorescence images, where the temporal information is encoded in the spatial distribution of photons across multiple frames. This substitution dramatically simplifies the device architecture while maintaining measurement capability.
Solution Approach 2:
The patent transforms the temporal measurement problem into a spatial problem by using a camera array or single camera with temporal encoding. The fluorescence lifetime information, which is inherently temporal, is mapped onto spatial coordinates of the detected photons. This dimensional transformation allows standard imaging devices to perform lifetime measurements without requiring specialized time-correlated electronics.
2Measurement precision
If frequency-domain methods with modulated excitation are used, then fluorescence lifetime can be measured, but the ability to resolve superimposed luminescence responses from multiple fluorophores is limited
Solution Approach 1:
The patent applies segmentation by dividing the detection process into multiple temporal bins or spatial zones. By capturing fluorescence signals at different time points or spatial locations, the method creates separate measurement channels that can be independently analyzed. This segmentation allows the decomposition of superimposed luminescence responses from multiple fluorophores with different lifetimes, as each fluorophore's signal preferentially appears in different temporal or spatial segments.
Solution Approach 2:
The patent employs periodic modulation of the excitation source and synchronizes camera exposure accordingly. By using periodic excitation and capturing images at specific phases of the modulation cycle, the method creates distinct temporal signatures for different fluorophores. This periodic action enables the separation of superimposed luminescence responses through phase-sensitive detection, where each fluorophore's lifetime manifests as a characteristic phase delay relative to the excitation modulation.
3Area of stationary object
If conventional microscopy methods are used for fluorescence imaging, then spatial resolution is achieved, but additional information about chemical environment and fluorophore properties is lost
Solution Approach 1:
The patent makes the imaging system universal by enabling it to perform multiple functions simultaneously. The same camera-based system that provides spatial imaging also extracts fluorescence lifetime information, which contains data about the chemical environment and fluorophore properties. This multi-functionality eliminates the need for separate intensity-based and lifetime-based measurement systems, allowing both spatial and spectral/temporal information to be obtained from a single integrated device.
Solution Approach 2:
The patent creates a composite measurement approach that combines spatial imaging with temporal lifetime measurement in a unified system. By integrating multiple measurement dimensions (space and time) into a single detection framework, the method generates composite information that simultaneously reveals spatial distribution and molecular environment characteristics. This composite measurement strategy provides a more comprehensive view of the sample than either spatial or temporal measurements alone.
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 enhances the precision in determining luminescence lifetimes, allowing for the separate calculation of lifetimes from multiple materials, even when responses are superimposed, thereby improving the accuracy of fluorescence imaging measurements.
Implementation Method 1
phase-sensitive detection of a luminescence response emitted by the object under investigation in response to the excitation radiation
Implementation Method 2
semiconductor-based radiation sources for phase-sensitive detection
Implementation Method 3
The luminescence response may specifically be fluorescence radiation, i.e., a fluorescence response, emitted by a material included in the object under investigation
Data Source
AI summary
An optical device for measuring luminescence includes a pulse generator for generating a periodic modulation signal having rectangular pulses, a pulse duration of the pulse being variably adjustable, an illumination device and/or means for illuminating an object under investigation with excitation radiation modulated in a pulse-like manner depending on the modulation signal, and a time-of-flight camera for phase-sensitive detection of a luminescence response emitted by the object under investigation in response to the excitation radiation. The modulation signal is supplied as reference signal to the time-of-flight camera. A method of measuring luminescence includes generating the periodic modulation signal having rectangular pulses, generating the signal-dependent, pulse-modulated excitation radiation, illuminating the object with the radiation, providing the modulation signal as reference signal to the camera, and performing phase-sensitive detection with the camera of the luminescence response emitted by the object in response to the excitation radiation for different pulse durations.