Biological Material Freezing via Pulsed Electric Fields

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Solution Overview

Problem

Current cryopreservation methods for biological materials often require the use of cryoprotectants, which are toxic and need to be removed after thawing, and result in ice crystal damage during freezing, leading to reduced viability of frozen samples.

Innovation Solution

A method and apparatus for freezing biological materials that control the phase transition time to less than 12 minutes, allowing for cryopreservation without cryoprotectants by determining a cooling profile that matches a calibration sample's phase transition time, thereby minimizing ice crystal formation and enhancing viability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard cryopreservation protocols using cryoprotectants are used, then cell viability is maintained, but the cryoprotectants are toxic and need to be removed after thawing

Engineering Contradiction:

Improvecell viabilityVSAvoidtoxicity of cryoprotectants

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the critical parameter of freezing rate to achieve ultra-fast freezing (greater than 1000°C per minute). This parameter change allows the system to bypass the need for cryoprotectants by preventing ice crystal formation through extremely rapid phase transition, thereby eliminating toxicity while maintaining cell viability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs periodic pulsed electric fields during the freezing process to enhance the ultra-fast freezing effect. The pulsed nature of the electric field application creates periodic thermal effects that accelerate heat removal and ensure complete prevention of ice crystal formation throughout the sample

Inventive Principle:

Principle #19Periodic action

2Reliability

If freezing rate is increased to reduce ice crystal formation, then cell viability improves, but the duration of latent heat removal must be precisely controlled

Engineering Contradiction:

Improvecell viabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention implements a feedback control system that continuously monitors the freezing process and adjusts the electric field application and cooling rate accordingly. Temperature sensors and control algorithms work together to maintain the precise freezing rate needed to prevent ice crystal formation while managing latent heat removal duration

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention replaces traditional mechanical cooling systems with an electric field-based freezing mechanism. By using pulsed electric fields to induce rapid heating and cooling cycles, the system achieves ultra-fast freezing rates without relying solely on mechanical refrigeration, thereby simplifying the overall control architecture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If ultra-fast freezing rate greater than 1000°C per minute is applied, then ice crystal formation is prevented and viability is maintained, but the phase transition time must be controlled to less than 12 minutes

Engineering Contradiction:

Improvecell viabilityVSAvoidphase transition time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention applies preliminary cooling to bring the sample close to the freezing point before initiating the ultra-fast freezing process. This preliminary action reduces the total phase transition time required and ensures that when the pulsed electric field is applied, the sample is already in the optimal temperature range for rapid freezing without ice crystal formation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention maintains continuous cooling throughout the freezing process to ensure that latent heat is constantly removed. This continuous action prevents temperature fluctuations that could lead to ice crystal formation and ensures the phase transition completes within the critical 12-minute window, maintaining cell viability

Inventive Principle:

Principle #20Continuity of useful action

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 increases the viability of frozen biological materials by reducing the duration of latent heat removal, achieving comparable results to standard protocols using cryoprotectants while eliminating their toxicity concerns.

Implementation Method 1

When liquid water is cooled it undergoes a phase transition from liquid to solid at a critical temperature. The phase transition is a first-order transition, which means the water either absorbs or releases an amount of energy per volume known as the latent heat. During the phase transition the temperature of the water will remain constant as heat is added or removed

Methodology Applied

Scientific EffectLatent heat removal: Latent Heat

Implementation Method 2

When liquid water is cooled it undergoes a phase transition from liquid to solid at a critical temperature. The phase transition is a first-order transition

Methodology Applied

Scientific EffectPhase transition: Phase Change