Tissue Loading, Flow Through Microchamber for Microscope Observation

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Tissue Loading Micro-Chamber
Flow-Through Environment for High-Power
Microscopic Observation
Aaron Desjarlais Jessica Kornfeld Michael
Lee Matthew McGrath Jeff Perry
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Problem Statement

• Mechanism to apply small uniaxial load to live
  tissue sample
• Record strain, load, displacement while operation
  is underway
• Provide interface with the Nikon TE2000E Inverted
  Optical Microscope
• Temperature-controlled environment
• Provide for media flow through device to sustain
  specimen for long time periods

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Background - Collagen

• Collagen is the most abundant protein on Earth
• Structural molecule of choice for vertebrates
• Bears and transmits tensile loads applied to the
  body
• Connective collagenous tissue naturally
  degenerates
• Decline of usable collagen-based tissue
• Increase in growing tissue in the laboratory
  environment

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Background - Project

• Collagenous tissue adapts to its environment
• When applying a load, extracellular matrix
  remodels in response to strain
• Difficult to observe in vivo due to need for
  high-power objectives

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Literature Search
Instron Planar-Biaxial Soft Tissue Test System
Instron - BioPuls Submersible Pneumatic Grips and
Temperature-Controlled Bath
Bose BioDynamic test systems
Capstone Project (Spring 2005) Refined by Kelli
Church for masters thesis (Spring 2007)
Bioptechs Chamber
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Requirements - Specifications

• Must be attachable to Nikon TE2000E stage
• Placement 200µm from objective lens
• Micro-chamber volume lt200 micro-liters
• Temperature 37C 0.5
• Tissue size 1cm x 1cm x 10 - 1000µm
• Uni-axial Load minimum 0.1N
• Strain Accuracy 1µm
• Record displacement, load, strain, and temperature

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Prototype Mounted on Microscope
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Proposed Design
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(No Transcript)
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Linear Guide System
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Guide System - Design Constraints

• Linearity
• The system must remain in camber
• Rigidity
• The system must be rigid enough so any
  displacement in the system does not add error to
  the measurement
• Size constraint
• Must fit under the condenser of the microscope

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Micro-Chamber Base
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Micro-Chamber Base - Design Constraints

• Rigidity
• The system must be rigid enough so any
  displacement in the system does not add error to
  the measurement
• Size
• The base must interface with existing mounting
  location on the microscope stage

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Micro-Chamber - Interior
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Material Selection

• 316 Stainless Steel
• High thermal conductivity 
• 16.3 W/m-K (113 BTU-in/hr-ft²-F)
• Operate at environmental temperature
• Melting Point 1370 - 1400 C (2500 - 2550 F)
• Corrosion resistant
• Can survive repeated common sterilization methods

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Micro-Chamber Exterior
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Material Selection

• Polycarbonate
• Low thermal conductivity
• 0.142 - 0.26 W/m-K (0.985 1.8 BTU-in/hr-ft²F)
• Corrosion resistant
• Sterilization
• Compatible with common clinical disinfectants
  isopropyl alcohol (rubbing alcohol)
• Low permeability
• Water absorption 0.0500 - 0.700

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Micro-Chamber Bacteria Sealing

• Dynamic elements two seals with antibacterial
  solution injected in between both seals
• Static elements single seal or gasket through
  compression to fill the gap
• 0.1 pounds of force is required per bolt on the
  Top Cover

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Drive/Sensor System
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Drive System Design Concepts
Pulley Drive Mechanism
Rack and Pinion Mechanism
Direct Drive Mechanism
Direct Drive with Spring Mechanism
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Linear Actuator

• Chosen Motor
• Zaber Technologies T-LA60A
• Accuracy 0.1 µm
• Already used on existing system
• Has manual control to ease setup
• Holds up to 15N continuous load

• Requirements
• Control and measure strain to 1 µm
• Allow for minimum 10mm of travel

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Force Transducer

• Requirements
• Uni-axial Load minimum 0.1N
• Miniature
• Submersible
• Corrosion resistant

• Selected Load Cell
• Sensotec Model 31
• Load capacity range from 50 g to 500 g (0.5 N to
  5 N)
• 17-4 PH stainless steel

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Control System

• LabView Control System
• Capable of Load or Strain Control
• Adjustable PID Parameters

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Control System
NI Labview Data Acquisition

• PID Toolkit
• Uses existing interface as baseline
• Signal conditioning card

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Load Control Tests

• Used Med-4720 silicone elastomer as specimen
• Tested using 0.1N as required load
• Max. error of 0.002N once steady state reached

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Tissue Grip Mechanism
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Grip Design

• Requirements
• Apply even clamping pressure
• Easy to operate
• Accommodate specimens up to 10mm wide, 10 µm to
  1000 µm thick
• Must be small to minimize chamber volume
• No part of the clamp must be lower than the sample

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Grip Design
Hinged Clamp
Sliding Plates
Sliding Bar Clamp
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Grip Design
Chosen Design Sliding Bar Clamp
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Thermal Control
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Selected Temperature Controller

• Omega CNi 3222-C24
• AutoTune PID High Accuracy 0.5C (0.9F), 0.03
  Reading
• 2 Outputs
• Dual Alarm
• Universal Input - Accepts all t/c and RTDs
• PC RS-232 output
• Free Software
• Ramp to Setpoint
• Cartridge Heaters
• Do not restrict design evolution
• Versatile, easily mounted
• Compact Design
• Powerful Element

From Spring 2005 Capstone Design Group
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Previous System
Cartridge heater Embedded in Copper Block
Quartz glass environmental Chamber
Drawings From Spring 2005 Capstone Design Group
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Heating System Components
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Heat Transfer Model Comparison
Previous Model
Present Model
Rcond,conv,fin (Top)
Rcond,conv (Top)
Rcond,conv, fin (Back)
Rcond,conv,fin (Front)
Rcond,conv (Back)
Rcond,conv (Front)
UP
Rcond,conv Robj cond, conv (Bottom)
UP
Rcond,conv,fin (Bottom)
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Temperature Controller Testing
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Temperature Testing Results
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Future Work

• Finish machining parts to specifications,
  primarily the adjustable piston
• Program system to operate in parameters of strain
  control
• Fully functional testing including, cornea
  loading and fluid heating assessment
• Micro-Chamber volume minimization

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Questions?
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Backup Slides
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Linear ActuatorTrade Study
From Spring 2005 Capstone Design Group
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Heat Source
From Spring 2005 Capstone Design Group
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Temperature ControllerTrade Study
From Spring 2005 Capstone Design Group
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Results of Heat Transfer Analysis Heating Chamber
From Spring 2005 Capstone Design Group
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Nodal Analysis

• System Divided into 37 Nodes, 6 fluid Nodes
• Boundary Conditions
• System begins at ambient temperature in air
• Fluid enters at room temperature and exits into
  large reservoir at room temperature
• System is symmetrical on either side of the
  chamber.

From Spring 2005 Capstone Design Group
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Equivalent Circuit Analysis

• Equivalent Circuit for Node 1
• qin qout qstored
• (?cV)cudT SCij(Tji) (q A)
• dt
• (?cV)cu?T SCij(Tji) (q A)
• ?t
• ?T ?t SCij(Tji) (q A)
• (?cV)cu
• Tf -Ti ?t SCij(Tji) (q A)
• (?cV)cu
• Tf Ti ?t SCij(Tji) (q
  A)
• Equivalent Circuit for Node 31
• Ein Eout Estored
• qin qout qstored , q qcond qe
• (qc qe)in (qc qe)out qstored
• (?c)l ve Af dT/dt q31-32 q31-cu qe
• (?c)l ve Af ?T/?t q31-32 q31-cu qe
  
• ?T ?t / (?c)l ve Af (q31-32 q31-cu
  qe)

1/hA (kA/L)ins (kA/L)cu
T8, h8 (Top face) (Left face) (Back face)
qheater
C12kA/L
1
2 (right face)
C16kA/L
6 (front face)
C1-11
11 (bottom face)
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?cveAf(T32T31)/2
1/hlAf
2prcukcu/ln(rcu/ro)
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2prcukcu/ln(rcu/ro)
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?cveAf(T8Ti)/2
ri ro rcu
T8, h8
From Spring 2005 Capstone Design Group
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Results of Heat Transfer Analysis Chamber Fluid
From Spring 2005 Capstone Design Group
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Results of Heat Transfer Analysis Tubing Fluid
Temperature
From Spring 2005 Capstone Design Group
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Translation Block Stress Analysis
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Base Stress Analysis
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Base Deflection Analysis
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Stainless Steel 316

• Thermal Conductivity 
• 16.3 W/m-K (113 BTU-in/hr-ft²-F)
• Melting Point
• 1370 - 1400 C (2500 - 2550 F)
• Common Applications
• Food and pharmaceutical processing equipment
• Marine exterior trim
• Surgical implants
• Industrial equipment for corrosive process
  chemicals

http//www.matweb.com/search/SpecificMaterial.asp?
bassnumMQ316J
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Polycarbonate

• Low permeability
• Water absorption 0.0500 - 0.700
• Low thermal conductivity
• 0.142 - 0.26 W/m-K (0.985 1.8 BTU-in/hr-ft²F)
• Sterilization dependent on the grade
• Ethylene oxide (EtO), Irradiation (both gamma and
  electron-beam), Steam autoclaving
• Cannot withstand repeated autoclaving
• Can be disinfected with common clinical
  disinfectants, isopropyl alcohol (rubbing
  alcohol)
• Common Applications
• IV connectors Surgical Instruments/Products

http//devicelink.com/mpb/archive/98/09/003.html
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Clamp Force Calculation for Gasket
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Internal Chamber Pressure
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Gasket Calculations
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Gasket Calculations
0.1 pounds of force is required per bolt
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Spring

• Actuator limits the displacement
• Used to exert the force
• Must not exceed capabilities of actuator
• Small Parts Part No. CSMW-0154-10
• OD 0.36 in.
• Wire Size 0.026 in.
• Free Length 2 in.
• Spring Rate 2.1 lbs/in