Freezing Microtome Liquid Coolant to Prevent Tissue Ice Damage

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Solution Overview

Problem

Existing freezing microtomes cause tissue damage due to the formation of elongated ice crystals during freezing, leading to freezing artifacts that degrade sample quality and complicate diagnosis.

Innovation Solution

Integration of a liquid coolant with a temperature range of -60° C to 0° C and specific heat capacity of 1.6 to 3.5 kJ/kg·K within the freezing microtome, forming small spherical ice crystals that preserve tissue morphology and prevent enzyme release, along with a cooling device and rinsing system to maintain optimal temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If tissue samples are frozen using conventional cooling devices with freezing ribs, then the tissue samples can be cooled and cut in the same device, but elongated ice crystals form that damage cells and degrade sample quality

Engineering Contradiction:

Improveintegration of cooling and cutting in one deviceVSAvoidfreezing artifacts and cell damage

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A container filled with liquid coolant serves as an intermediary medium to transfer cold to the tissue samples. The coolant circulates between the cooling device and sample container, indirect cooling prevents direct contact between freezing surfaces and tissue, thereby avoiding ice crystal formation while maintaining the integrated cooling-cutting functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a liquid coolant circulation system (hydraulic principle) to transfer thermal energy. The coolant is pumped through channels in the cooling device and circulated to the sample container, enabling controlled, uniform cooling that prevents damaging ice crystal formation while maintaining operational integration

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Object-affected harmful factors

If tissue samples are frozen externally using liquid nitrogen or nitrogen-cooled isopentane, then freezing artifacts are avoided, but the process becomes complex, expensive, and risks mixing up samples

Engineering Contradiction:

Improvefreezing artifactsVSAvoidexternal freezing process complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention merges the cooling function and cutting function into a single integrated device. The cooling device with liquid coolant circulation is combined with the cutting device in one unit, eliminating the need for separate external freezing steps while maintaining artifact-free freezing through controlled coolant circulation

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated device performs both cooling and cutting functions autonomously. The cooling system prepares the tissue samples in situ within the same device that performs cutting, eliminating the need to transfer samples between separate freezing and cutting devices, thereby preventing sample mix-up and simplifying the overall process

Inventive Principle:

Principle #25Self-service

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 significantly reduces freezing artifacts, allowing for high-quality thin section production and stable mRNA extraction, enhancing diagnostic accuracy by preserving cellular structures and preventing enzyme degradation.

Implementation Method 1

For freezing the tissue samples, the liquid coolant preferably has a temperature within a range from approximately −60° C. to 0° C.

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

it has turned out that if a liquid coolant with these characteristics is used, the cellular and extracellular water when the tissue is frozen only forms small, spherical ice crystals which neither damage the cells nor the cell walls

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

the cooling device includes a tank arranged in the working chamber for receiving the liquid coolant

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS8959935B2Freezing microtome and method for producing microscopable thin sections

Publication Date: 2015.02.24 LEICA BIOSYSTEMS NUSSLOCH GMBH

AI summary

A freezing microtome for the production of microscopable thin sections of tissue samples (60), comprising a cooling device (24, 34, 36, 38, 40, 42, 46, 48, 50, 52) for freezing the tissue samples (60), a cutting device for cutting the frozen tissue samples (60) and a working chamber, in which the cutting device and at least a part of the cooling device (24, 34, 36, 38, 40, 42, 46, 48, 50, 52) are arranged is described. The part of the cooling device (24, 34, 36, 38, 40, 42, 46, 48, 50, 52) arranged in the working chamber contains a liquid coolant (70), in which the tissue samples (60) can be inserted for freezing.