Vibrating Plasmonic Tip-Enhanced Spectroscopy for Liquid Analytes
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Solution Overview
Problem
Tip-enhanced spectroscopy systems are limited to observing analytes in vacuum or air due to sensitivity to the operating environment, preventing analysis of analytes in liquid environments such as biomolecules and water-decomposition energy production materials.
Innovation Solution
A plasmonic material-based tip is used to minimize the effect of surface tension in liquid environments by adjusting the harmonic vibration shape and length to improve spatial resolution and minimize displacement, allowing analysis of analytes in liquids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the tip length is increased to reach samples in liquid environment, then the ability to observe analytes in liquid is improved, but the displacement of the free end of the tip increases due to surface tension, worsening measurement precision
Solution Approach 1:
The tip is made to vibrate harmonically at its natural frequency, utilizing vibration nodes to create a measurement point that is insensitive to surface tension forces. The vibration mode is selected such that a node (point of minimal displacement) coincides with the liquid surface intersection point, allowing the tip to reach into liquid while maintaining measurement precision at the node location.
Solution Approach 2:
The system transitions from a static tip to a dynamically vibrating tip, where the vibration state creates specific displacement patterns along the tip length. By operating at resonant frequencies, the tip develops nodes and antinodes, allowing the measurement point to be positioned at a node where displacement is minimized despite the tip extending into the liquid environment.
2Adaptability or versatility
If the tip extends deeper into liquid to reach the sample, then the ability to measure analytes in liquid is improved, but the effect of surface tension on tip vibration increases, worsening measurement stability
Solution Approach 1:
The tip vibrates harmonically at its natural frequency, creating stable vibration modes with fixed node positions. By positioning a vibration node at the liquid surface intersection, the measurement becomes stable and insensitive to variations in tip immersion depth, as the node position remains fixed during vibration.
Solution Approach 2:
The vibrating tip system can operate in multiple environments (air and liquid) by selecting appropriate vibration modes. The same tip structure and excitation mechanism work in both air and liquid, with the liquid surface simply becoming another point along the tip where a node can be positioned, rather than requiring different measurement approaches for different environments.
3Length of stationary object
If the tip length is increased to reach samples in liquid, then the ability to access liquid-phase analytes is improved, but the displacement of the free end increases, worsening spatial resolution
Solution Approach 1:
The tip is excited to vibrate harmonically, creating a standing wave pattern with nodes and antinodes. By positioning a node at the liquid surface and another node near the sample, the system achieves high spatial resolution at the measurement point even with a long tip, because the node positions are determined by the vibration mode rather than tip length alone.
Solution Approach 2:
The system changes the operational parameters by introducing vibration frequency as a control variable. By selecting specific resonant frequencies, the tip develops specific vibration modes with nodes at desired positions. This allows the measurement point to be positioned precisely near the sample regardless of the overall tip length, decoupling tip length from measurement precision.
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
Enables precise observation and analysis of analytes in liquids, such as biomolecules and quantum dots, with improved spatial resolution and reduced oxidation, facilitating real-time nanoscale measurement of energy production mechanisms.
Implementation Method 1
replaces a tip used in atomic force microscopy with a plasmonic material-based tip to focus strong light into an area of tens of nanometers, exceeds a diffraction limit of light
Implementation Method 2
the shape of the harmonic vibration is adjusted through the shape of the tip to secure the length of the tip that can reach the sample in the liquid while minimizing the displacement of the free end of the tip
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The present disclosure provides a tip-enhanced spectroscopy including a substrate on which liquid containing an analyte is positioned, a tip extending from a fixed end to a free end adjacent to the analyte, and a vibration source configured to harmonically vibrate the tip based on a preset natural frequency of a tuning fork.