SERS Liquid Sample Deoxygenation for Ultra-Low Analyte Detection
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Solution Overview
Problem
Raman spectroscopy has low sensitivity due to weak inelastic light scattering, and surface-enhanced Raman spectroscopy (SERS) is limited by detection limits at the nM or pM level, which can be further compromised by substrate oxidation and atmospheric carbon contamination, hindering single molecule detection.
Innovation Solution
The method involves adding an oxygen scavenger to a liquid sample to remove dissolved oxygen, enhancing SERS signal intensity by maintaining plasmonic field propagation, allowing for analyte detection down to zM levels and enabling remote sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional SERS detection is used, then analyte detection is achieved at nM or pM levels, but the detection sensitivity is limited and cannot reach single molecule detection limits
Solution Approach 1:
The patent applies preliminary action by performing pre-concentration of analytes using super-hydrophobic or omniphobic surfaces before SERS detection. This preparatory step accumulates analyte molecules at the water-air interface, ensuring sufficient analyte quantity is present at the detection location, thereby enabling detection at fM levels and approaching single molecule detection limits
Solution Approach 2:
The patent uses super-hydrophobic or omniphobic surfaces as an intermediary between the bulk liquid sample and the SERS detection system. These surfaces act as a mediator that selectively concentrates analytes from the bulk solution to the detection interface, enhancing the effective analyte concentration at the SERS-active hot spots without requiring direct contact with the entire sample volume
2Illumination intensity
If silver nanoparticles are used for SERS enhancement, then signal intensity is greatly enhanced, but substrate oxidation by ambient air decreases SERS enhancement factors by up to 10^5
Solution Approach 1:
The patent applies preliminary anti-action by using oxygen scavengers to remove dissolved oxygen from the liquid sample before SERS detection. This preventive measure counteracts the oxidation of silver nanoparticles by eliminating the oxidizing agent (dissolved oxygen) in advance, thereby maintaining the plasmonic properties and SERS enhancement factors without degradation from oxidation or atmospheric carbon contamination
Solution Approach 2:
The patent creates an inert environment by removing dissolved oxygen from the liquid sample using oxygen scavengers. This establishes an oxygen-free or low-oxygen environment that protects the silver nanoparticle substrate from oxidation, maintaining the reliability and stability of SERS enhancement factors during the detection process
3Measurement precision
If the sampling area for SERS detection is increased, then more analyte molecules can be detected, but the fraction of the whole sample volume that can be analyzed remains negligible
Solution Approach 1:
The patent uses super-hydrophobic or omniphobic surfaces as an intermediary that bridges the bulk sample volume and the limited SERS detection area. These surfaces concentrate analytes from the entire sample volume onto a small area at the water-air interface, effectively decoupling the sampling area from the sample volume and enabling high detection capability without requiring large sampling areas
Solution Approach 2:
The patent extracts analyte molecules from the bulk liquid sample and concentrates them at the water-air interface using super-hydrophobic or omniphobic surfaces. This extraction and concentration process transfers analytes from the bulk volume to a localized region, enabling efficient SERS detection of a representative portion of the entire sample without needing to analyze the whole volume
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 method achieves a significant reduction in the limit of detection (LOD) for analytes in liquid samples by at least a factor of 108, reaching zM levels and facilitating remote sensing through improved SERS signal intensity.
Implementation Method 1
adding an oxygen scavenger to the liquid sample so as to remove dissolved oxygen from the liquid sample
Implementation Method 2
Surface enhanced Raman spectroscopy (SERS) increases the intensity of inelastically scattered light by increasing the probability that light will be scattered inelastically rather than elastically
Implementation Method 3
The precise mechanism through which the enhancement occurs is currently being debated in thescientific community, but it is known that the plasmonic material must be rough at the nanoscale or be comprised of nanostructures
Data Source
AI summary
A method of modifying a liquid sample containing an analyte so as to increase SERS signal intensity of the analyte is provided. The method of the present invention comprises the steps of: providing the liquid sample to be analyzed using SERS; and adding an oxygen scavenger to the liquid sample so as to remove dissolved oxygen from the liquid sample. A probe for remote sensing of an analyte in a liquid sample using SERS is also provided. The probe of the present invention comprises a detection chamber having a window that is transparent to SERS excitation light and Raman scattered signal, and tubing with a first and a second end, the first end of the tubing being flowably connected to the detection chamber and the second end of the tubing being configured to be placed in contact with a liquid sample.