A report presents discussion of time-resolved measurements in optoelectronic microbioanalysis. Proposed microbioanalytical "laboratory-on-a-chip" devices for detection of microbes and toxic chemicals would include optoelectronic sensors and associated electronic circuits that would look for fluorescence or phosphorescence signatures of multiple hazardous biomolecules in order to detect which ones were present in a given situation. The emphasis in the instant report is on gating an active-pixel sensor in the time domain, instead of filtering light in the wavelength domain, to prevent the sensor from responding to a laser pulse used to excite fluorescence or phosphorescence while enabling the sensor to respond to the decaying fluorescence or phosphorescence signal that follows the laser pulse. The active-pixel sensor would be turned on after the laser pulse and would be used to either integrate the fluorescence or phosphorescence signal over several lifetimes and many excitation pulses or else take time-resolved measurements of the fluorescence or phosphorescence. The report also discusses issues of multiplexing and of using time-resolved measurements of fluorophores with known different fluorescence lifetimes to distinguish among them.
This work was done by Gregory Bearman and Dmitri Kossakovski of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Bio-Medical category. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to
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Refer to NPO-21046, volume and number of this NASA Tech Briefs issue, and the page number.
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Time-Resolved Measurements in Optoelectronic Microbioanalysis
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Overview
The document discusses advancements in time-resolved measurements for optoelectronic microbioanalysis, particularly focusing on the use of Active Pixel Sensors (APS) for detecting microbes and toxic chemicals. The proposed technology aims to create "laboratory-on-a-chip" devices that can identify hazardous biomolecules by analyzing their fluorescence or phosphorescence signatures.
The motivation behind this research stems from the limitations of traditional optical absorption analysis methods, which are less sensitive compared to fluorescence detection. In typical applications, a film is deposited on the APS surface, and its optical properties change upon exposure to specific agents due to antigen-antibody binding. Monitoring these changes allows for qualitative and quantitative analysis of the target substances.
However, using APS as both a detector and substrate presents challenges, particularly in separating the excitation light from the emitted fluorescence. Conventional methods, such as dichroic beamsplitters, are not feasible due to the lack of space between the film and the APS. Additionally, depositing optical filters on the APS is problematic due to its surface topography, which can lead to increased cross-talk and reduced spatial resolution.
To address these issues, the document proposes a novel solution: separating excitation and emission signals in the time domain rather than the wavelength domain. This involves pulsing the excitation light and synchronizing the APS to acquire signals after the excitation pulse, effectively eliminating the need for color separation. This method allows the APS to capture the decaying fluorescence or phosphorescence signal without interference from the excitation light.
The report emphasizes the potential of this approach for multiplexing, enabling the detection of multiple fluorophores with different fluorescence lifetimes. By integrating or taking time-resolved measurements of these signals, the technology can distinguish among various biomolecules, enhancing the sensitivity and specificity of the analysis.
Overall, the work presented in the document represents a significant advancement in the field of microbioanalysis, promising improved detection capabilities for hazardous substances in various applications. The research was conducted by Gregory Bearman and Dmitri Kossakovski at the Jet Propulsion Laboratory, California Institute of Technology, under NASA's sponsorship.
