Cryogenic Freezing of Dissection Samples

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Cryogenic Freezing of Dissection Samples

• Gretchen Foltz, Marie Meyer, Kristy Wood, and
  Jodi Zilinski
• BME 400
• October 19th, 2001

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• ClientProfessor Barry Ganetzky
• YoungHo Koh, PhDDepartment of GeneticsUniversity
  of Wisconsin MadisonAdvisorMitch
  TylerDepartment of Biomedical EngineeringDepartm
  ent of Rehabilitative MedicineUniversity of
  Wisconsin - Madison

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Overview

• Problem Statement
• Background
• Key Specifications
• Design Overview
• Components
• Cooling Mechanism
• Electrical Control
• Spray Chamber
• Final Design Preview
• Future Aspects
• Questions

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Problem Statement

• To design a device which is able to
• Rapidly freeze biological specimens
• Provide maximum vitrification
• Preserve morphology

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Background

• Study of Synapses in Drosophilia
• Electron Scanning Microscope
• Requires New Fixation Techniques

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Key Specifications

• Preservation of Morphology
• Rate of Freezing
• Cost
• Regulation of Cryogen Flow, Temperature, and
  Pressure

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Design Overview
Phase I
Phase II
Phase III
Cooling Mechanism
Overall Design
Integration And Testing
Electronic Control
Spray Chamber
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Cooling Mechanism

• Primary Cryogen Liquid Nitrogen
• Secondary Cryogen Propane
• Component Elements
• Flow Rates
• Cryogen Volumes
• Length of the Copper Tubing

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Thermo Calculations

• Amount of heat that must be removed for the
  sample to properly freeze specimen.
• Amount of liquid propane needed to extract the
  heat in the sample.
• Amount of liquid nitrogen needed to condense and
  cool the propane.
• Length of copper tubing.

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Thermo Calculations
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Electronic Control
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Spray Chamber

• Spray Mechanism
• Insulating Materials
• Vacuum Pump
• Solenoid Valves

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Final Design Preview
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Spray Nozzle
Copper Tubing
ID 0.4868 cm OD 0.9970 cm
5 cm
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Copper Tubing
15 cm
Flask
15 cm
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Copper Tubing
15 cm
1 cm
Platform
Flask
15 cm
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21 cm
15 cm
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Future Aspects

• Complete Engineering Drawings
• Build Prototype
• Testing
• Run a Design of Experiment to Optimize Cryogen
  Flow
• Make Necessary Adjustments to Design for
  Construction of Final Product
• Write Safety Manual for Operation

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Questions