Cryogenic Probe Tip Bonding for Vitrified Specimen Extraction

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Solution Overview

Problem

Existing methods for bonding frozen biological specimens to probe tips or sample holders in FIB instruments risk devitrification and ice crystal formation, which damages the specimen's structure and interferes with imaging.

Innovation Solution

A method using controlled vapor attachment, where water vapor or other condensates are directed to form a conformal, amorphous ice layer at cryogenic temperatures, ensuring the specimen and probe tip remain at the same temperature, preventing phase changes and ice crystal formation, and allowing secure bonding without damaging the specimen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a warm probe tip is touched to a vitrified biological specimen to achieve bonding, then bonding is achieved, but ice crystals form in the specimen causing structural damage

Engineering Contradiction:

Improvebonding strengthVSAvoidice crystal formation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter of the probe tip from warm to cryogenic temperatures, matching the specimen temperature. This prevents the phase change that causes ice crystal formation while still enabling bonding through controlled vapor deposition at the cold interface.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces water vapor as an intermediary substance that deposits as amorphous ice at the cold interface between the probe tip and specimen. This vapor-mediated bonding process occurs at cryogenic temperatures without causing devitrification or ice crystal formation in the specimen.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If temperature manipulation is used to achieve bonding, then bonding is achieved, but the specimen temperature may rise above vitrification temperature causing devitrification

Engineering Contradiction:

Improvebonding strengthVSAvoidvitrification state

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent maintains the specimen temperature below the vitrification temperature throughout the bonding process by using cryogenic temperatures and controlled vapor deposition. This preserves the amorphous ice state and prevents devitrification while achieving secure bonding.

Inventive Principle:

Principle #35Parameter changes

3Strength

If gas-assisted ion and electron deposition processes are used for bonding, then bonding is achieved, but uncontrollable condensation of metallo-organic precursors results in suboptimal masking layer

Engineering Contradiction:

Improvebonding strengthVSAvoidmasking layer quality

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent uses water vapor instead of expensive metallo-organic precursors. The water vapor deposits as amorphous ice that serves as both the bonding medium and a sufficient masking layer, eliminating the need for complex gas-assisted deposition processes and their associated control problems.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 enables secure bonding of frozen specimens to probe tips or other objects without inducing ice crystals or frost, preserving the specimen's morphological integrity and preventing artifacts during FIB milling and imaging.

Implementation Method 1

controlled vapor attachment, where water vapor or other condensates are directed to form a conformal, amorphous ice layer

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 2

water vapor or other condensates are directed to form a conformal, amorphous ice layer at cryogenic temperatures

Methodology Applied

Scientific EffectFreezing: Freezing

Implementation Method 3

ensuring the specimen and probe tip remain at the same temperature, preventing phase changes and ice crystal formation

Methodology Applied

Scientific EffectCryogenic cooling: Cryogenics

Data Source

PatentUS8513622B2Method for extracting frozen specimens and manufacture of specimen assemblies

Publication Date: 2013.08.20 OXFORD INSTR AMERICA

AI summary

A method for attaching a frozen specimen to a manipulator probe tip typically inside a charged-particle beam microscope. The method comprises cooling the probe tip to a temperature at or below that of the frozen specimen, where the temperature of the frozen specimen is preferably at or below the vitrification temperature of water; bringing the probe tip into contact with the frozen specimen, and bonding the probe tip to the frozen specimen by flowing water vapor onto the region of contact between the probe tip and the frozen specimen. The bonded probe tip and specimen may be moved to a support structure such as a TEM grid and bonded to it by similar means. The probe tip can then be disconnected by heating the probe tip or applying a charged-particle beam.