Thermal Desorption Probe for Sub-Micron Chemical Analysis
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Solution Overview
Problem
Current analytical techniques for chemical composition analysis at the nanoscale are limited in providing spatial resolution and chemical information, with methods like electron microscopy and Raman imaging offering little chemical detail, while mass spectrometry is restricted to high vacuum and specialized sample preparation.
Innovation Solution
A system and method utilizing a thermal desorption probe with a thermally active tip of 250 nm or less, capable of heating to above 200°C, to desorb and ionize analytes from a specimen, allowing for high spatial-resolution analysis and integration with mass spectrometry for chemical composition determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass spectrometry-based techniques are used to provide precise molecular mass and chemical structure information, then chemical information accuracy is improved, but the technique is limited to operation in high vacuum and often involves highly specialized sample preparation techniques
Solution Approach 1:
The patent extracts the ionization and mass analysis capability from the high vacuum environment requirement by introducing a differential pumping system with a first vacuum stage and second vacuum stage separated by an aperture. This allows the thermal desorption probe to operate in atmospheric conditions while the mass spectrometer operates in vacuum, eliminating the need for specialized vacuum sample preparation.
Solution Approach 2:
The patent introduces a differential pumping system as an intermediary between the atmospheric pressure thermal desorption region and the vacuum mass spectrometer region. This intermediary system with multiple pumping stages and apertures mediates the transition of ions from atmospheric to vacuum conditions without requiring the sample preparation to be adapted for vacuum.
2Manufacturing precision
If electron microscopy or scanning probe microscopy is used to achieve spatial imaging resolution of 1 nm or better, then spatial resolution is improved, but almost no chemical information about the sample is provided
Solution Approach 1:
The patent merges the high spatial resolution capability of scanning probe microscopy (using a probe with apex radius of 250 nm or less) with the chemical identification capability of mass spectrometry. The thermal desorption probe maintains nanoscale spatial resolution while the desorbed molecules are analyzed by mass spectrometer to provide precise chemical structure information, thus combining both advantages.
Solution Approach 2:
The patent creates a multi-functional system where the probe serves dual purposes: as a scanning probe for high-resolution spatial imaging and as a thermal desorption source for chemical analysis. This universal probe design allows the same instrument to provide both topographic information and chemical composition data without requiring separate specialized equipment.
3Loss of information
If Raman or IR imaging is used to provide molecular level chemical information, then chemical information is improved, but spatial resolution is limited compared to microscopy techniques
Solution Approach 1:
The patent segments the chemical analysis process into localized thermal desorption events at the probe apex, which has a radius of 250 nm or less. This segmentation allows chemical information to be obtained from extremely small spatial regions, achieving spatial resolution comparable to microscopy techniques while providing comprehensive molecular-level chemical information through mass spectrometry.
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 sub-micron resolution chemical composition analysis at atmospheric pressure, capable of detecting attomole quantities, and provides both topographic and chemical mapping of specimen surfaces, overcoming limitations of existing techniques.
Implementation Method 1
heating the thermally active tip to a temperature greater than 200° C. while proximate the target site in order to cause analytes at the plurality of target sites to form gaseous analytes
Implementation Method 2
a collection device arranged to capture an gaseous analyte desorbed from a specimen by the thermal desorption probe
Implementation Method 3
ionizing the gaseous analyte to form an ionized analyte
Data Source
AI summary
A system and method for sub-micron analysis of a chemical composition of a specimen are described. The method includes providing a specimen for evaluation and a thermal desorption probe, thermally desorbing an analyte from a target site of said specimen using the thermally active tip to form a gaseous analyte, ionizing the gaseous analyte to form an ionized analyte, and analyzing a chemical composition of the ionized analyte. The thermally desorbing step can include heating said thermally active tip to above 200° C., and positioning the target site and the thermally active tip such that the heating step forms the gaseous analyte. The thermal desorption probe can include a thermally active tip extending from a cantilever body and an apex of the thermally active tip can have a radius of 250 nm or less.