CellScale UniVert User manual

UniVert
Mechanical Test System
User Manual
version 3.0

Mechanical measurement and analysis of materials
CellScale provides scientific and medical researchers with turn-key systems for
measuring the mechanical properties of materials. We provide user-friendly
software, an easy-to-use patented attachment system, and effective data
analysis tools.
Our foundation was laid at one of the world’s leading research institutions –the
University of Waterloo. We understand research and aim to provide effective
solutions at a reasonable price.
Explore our web site www.cellscale.com or contact us to learn more about our
measurement systems.
© 2021 CellScale. All rights reserved. This material may not be reproduced,
displayed, modified, or distributed without the express prior written permission of the
copyright holder. For permission, contact CellScale Biomaterials Testing at
[email protected].
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Table of Contents
General Information......................................................................................................................... 1
Environmental and Electrical Specifications................................................................................ 1
System Assembly......................................................................................................................... 1
Connections to Supply................................................................................................................. 1
Safety Warnings........................................................................................................................... 2
Manual Operating Controls.......................................................................................................... 2
General Maintenance................................................................................................................... 2
Approvals and Certification.......................................................................................................... 2
Testing Terminology........................................................................................................................ 3
Multiphase Test Cycles................................................................................................................ 3
Phases, Cycles, and Test Sequences......................................................................................... 4
Test Phases: The Smallest Unit of Testing.................................................................................. 5
Control Modes.............................................................................................................................. 5
Control Functions......................................................................................................................... 6
Test Modes and System Configurations...................................................................................... 7
Software Overview........................................................................................................................... 8
Output Files and Data Structures................................................................................................. 9
Setting Up & Starting a Test.......................................................................................................... 10
Overview.................................................................................................................................... 10
Step 1: Start a New Test............................................................................................................ 10
Step 2: Reset the Actuator......................................................................................................... 11
Step 3: Specify Test Type.......................................................................................................... 12
Step 4: Zero the Load Cell (occasionally).................................................................................. 12
Step 5: Modify Testing Parameters (optional) ........................................................................... 13
Step 6: Mounting a Specimen.................................................................................................... 15
Platen Mounted Specimens ................................................................................................... 15
Grip Mounted Specimens....................................................................................................... 16
3-Point Bend Specimens........................................................................................................ 18
Step 7: Execute the Test............................................................................................................ 19
Step 8: Terminate the Test Prematurely (optional).................................................................... 19
Step 9: Saving the Template (optional) ..................................................................................... 20
Additional Settings......................................................................................................................... 21
Configuring Output Data Files.................................................................................................... 21
Advanced System Settings Dialogue......................................................................................... 22
Data Averaging....................................................................................................................... 22

Force Control Settings............................................................................................................ 23
Force and Displacement Control Settings.............................................................................. 24
System Stiffness Compensation ............................................................................................ 24
Range Limits.............................................................................................................................. 25
Configuring the Live Charting Graphs ....................................................................................... 26
Reviewing Test Results................................................................................................................. 28
Overview.................................................................................................................................... 28
Selecting Images........................................................................................................................ 29
Image Playback Options............................................................................................................ 29
Image Tracking: Overview ......................................................................................................... 30
Image Tracking: The Points Display Option .............................................................................. 33
Camera ...................................................................................................................................... 34
Image Tracking: The Displacement Option ............................................................................... 35
Image Tracking: The Strains Option.......................................................................................... 36
Data Overlay.............................................................................................................................. 37
Exporting Tracked Data ............................................................................................................. 38
Exporting Images and Movies.................................................................................................... 40
System Hardware Settings............................................................................................................ 41
Controller.................................................................................................................................... 41
Load Cell.................................................................................................................................... 41
Actuator and Motor .................................................................................................................... 42
Temperature............................................................................................................................... 43
System Calibration and Advanced Tools ...................................................................................... 44
Load Cell Calibration.................................................................................................................. 44
Attached to System ................................................................................................................ 44
Calibration Plates ................................................................................................................... 47
Zero Position Calibration............................................................................................................ 49
Custom Position Calibration....................................................................................................... 51
System Stiffness Compensation................................................................................................ 52
Snap Image Feature .................................................................................................................. 55
Update Firmware........................................................................................................................ 55
Troubleshooting............................................................................................................................. 57
Communication Errors: Read File or Write File ......................................................................... 57
Actuator Limits ........................................................................................................................... 58
Emergency Stop......................................................................................................................... 60
Appendix A: Unpacking and Initial Setup ...................................................................................... 61
Tools .......................................................................................................................................... 61

Components............................................................................................................................... 61
Fasteners................................................................................................................................... 65
Appendix B: Load Cell Installation................................................................................................. 70
Appendix C: Software Installation.................................................................................................. 72
Appendix D: Test Setup................................................................................................................. 78
Tension Test Setup.................................................................................................................... 78
Vertical Configuration............................................................................................................. 79
Horizontal Configuration......................................................................................................... 82
Compression Test Setup ........................................................................................................... 85
Vertical Configuration............................................................................................................. 85
Horizontal Configuration......................................................................................................... 87
3-Point Bend Test Setup............................................................................................................ 89
Appendix E: Camera Setup........................................................................................................... 92
Webcam..................................................................................................................................... 92
Scientific Camera....................................................................................................................... 93
Appendix F: Media Bath Setup...................................................................................................... 99
Vertical Media Bath.................................................................................................................... 99
Horizontal Media Bath.............................................................................................................. 106
Appendix G: Changing Grip Springs ........................................................................................... 112
Appendix H: Low Force Load Cells............................................................................................. 116
Tension Test Setup.................................................................................................................. 117
Vertical Configuration........................................................................................................... 118
Horizontal Configuration....................................................................................................... 120
Changing Grip Springs......................................................................................................... 122
Compression Test Setup ......................................................................................................... 125
Vertical Configuration........................................................................................................... 126
Horizontal Configuration....................................................................................................... 127

UniVert User Manual
1
General Information
The UniVert is a precision test instrument designed for the compressive and tensile testing and
analysis of materials including polymers, biological specimens, and 3D-printed constructs. The
UniVert system includes a test station and an integrated software interface to run and analyze
test results.
Environmental and Electrical Specifications
Electrical Input
100-240VAC, 50-60Hz
Current Rating
2.71 Amp
Environmental
Conditions
Maximum Operating Temperature
25ºC
0% - 95% Relative Humidity
Installation Category
Category II
Pollution Degree
Degree 2
Data Connections
1 –USB for camera/PC
communication
(USB 3.0 for scientific camera)
1 –USB for controller/PC
communication
System Assembly
Some basic assembly and setup is required. An unboxing and setup guide can be found in
Appendix A.Load cell installation is detailed in Appendix B and software installation is
described in Appendix C. Test setup and configurations are described in Appendix D. Camera
setup is described in Appendix E.
Connections to Supply
Connect the power supply into a properly grounded 100-240VAC power source to ensure safe
operation. Ensure that the power cord is easily accessible at all times. The use of an
Uninterruptible Power Supply (UPS) is recommended to protect against data loss.
The mains supply voltage fluctuations should not exceed 10% of the nominal supply voltage.

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2
Safety Warnings
This equipment must be used in accordance with the procedures outlined in this manual.
Operators of this equipment must be instructed in safe operating procedures to prevent injury
and/or damage.
Ensure that the area around the moving actuator is clear before commencing test protocols.
The UniVert presents a pinch hazard to extremities. Keep hands clear of moving parts for the
duration of the test.
Manual Operating Controls
There are 2 manual switches on the front of the baseplate. The main power switch of the UniVert
system is the leftmost switch (activating a green LED) and the Emergency stop switch (E-stop) is
rightmost. The E-stop will stop power to the motor and instruct the software to stop a test if one
has been executed. If the E-stop has been depressed, it must be rotated to return it back to its
original position.
The E-stop should only be used in emergency situations only since it will require a power cycle
and actuator reset to set up a new test after it has been depressed (see Setting Up & Starting a
Test: Step 8 for more details).
General Maintenance
Clean the system as needed with mild detergent and water or alcohol based cleaning solutions.
Approvals and Certification
This product conforms to applicable CE standards.
System Alert
This equipment must not be disassembled by the user or modified in any way except that
which is described in this manual.

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3
Testing Terminology
The UniVert is designed to apply uniaxial compressive and tensile forces to a variety of materials.
This includes soft metals, plastics, and composites as well as biological materials.
Multiphase Test Cycles
In order to properly characterize and test a specimen, it is often necessary to load it to different
degrees and at different rates. There are three main reasons for doing this:
Preconditioning - Especially for biological specimens, the goal of preconditioning is to restore a
specimen to its physiological or in vivo state. During the process of specimen storage and
preparation, a specimen may swell, dry out, have its material fibers realign, or its molecules
reorganize. It may take multiple preconditioning cycles for a specimen to be restored to its natural
state.
Reproducing Physiological Conditions During Testing - By applying various loads and load
rates, natural expansion and contraction of a specimen can be reproduced (for example, the
pulse pressure in an organ). In as much as the physiological conditions can be recreated, the
specimen can be tested in a more realistic state.
Varying Test Conditions - Variable loads and rates allow you to create a variety of test profiles
to best study your specimen.

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Phases, Cycles, and Test Sequences
As the following diagram demonstrates, each application and release of load on the specimen is
called a test cycle. The same test cycle can be repeated multiple times to achieve a certain goal
(preconditioning, physiological conditioning, or testing); this is called a test set. Finally, a test
sequence is made up of multiple test sets.
The above example describes the following:
•The entire diagram presents a full test sequence.
•Within that sequence, there are two test sets: the first set applies preconditioning to the
specimen; the second set executes the actual test on the specimen.
•Within the first set (preconditioning), two identical test cycles are implemented to bring
the sample to a satisfactorily preconditioned state.
•Finally, the second set (testing) is made up of three cycles.

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5
Test Phases: The Smallest Unit of Testing
The test phase is the smallest unit of the test specification. There are five phases within a cycle.
Each phase serves a specific purpose:
Preloading- Preloads are applied to bring a test to a well-
defined starting point. Because the dimensions of a
specimen may change as a result of a loading cycle
(stretching of fibers, viscoelastic effects, plastic
deformation, or localized material failure at the attachment
points), the preload adjustment compensates for any of
these changes in specimen geometry.
Stretching - During the stretch phase, a deformation is
applied to the specimen. The deformation can be specified
either in terms of force applied or displacement achieved.
Note that in this context, the stretch phase refers to either
stretching (for a tension test), or compression (for a
compressive test).
Holding - The deformation can be held for a given
duration. The duration for which it is held is dependent on the nature of the testing.
Recovering - The recovery phase is the time during which the force being applied to the
specimen is removed. The duration of the recovery time is configurable and dependent on the
nature of the testing.
Resting - Finally, the rest phase is the time between the end of one cycle and the beginning of
the next. Some tests may specify a short recover time or no recover time, while others may
specify a longer time. The duration is configurable and dependent on the nature of the testing.
Control Modes
There are two control modes which define the basic approach to a given test: displacement
control and force control:
Under displacement control, the displacement of the specimen is predefined. The
UniVert stretches or compresses the specimen until the predefined displacement is
achieved (specified in mm or %). The force required to achieve the displacement is an
output of the test.
Under force control, the force applied to the specimen is predefined. The UniVert
stretches or compresses the specimen until the predefined force is achieved (specified in
newtons [N]). The displacement required to achieve the force is an output of the test.

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Control Functions
The UniVert makes it possible to test specimens under several control functions:
Under displacement control:
The true strain function applies the displacement at a true strain rate, which accounts
for the current specimen length while the specimen is being stretched and continuously
recalculates the velocity. The UniVert system approximates this with a series of linear
segments.
The ramp function applies the displacement at a constant nominal rate. This is
equivalent to engineering strain or constant velocity.
The sinusoid function applies the displacement according to a sinusoid with the desired
displacement magnitude and duration. The UniVert system approximates this with a
series of linear segments.
Under force control:
The ramp function applies the force at a constant nominal rate. This is equivalent to
engineering strain or constant velocity. The result of this test will depend on the material
being tested and the force control settings.
The sinusoid function applies the force according to a sinusoid with the desired force
magnitude and duration.

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Test Modes and System Configurations
There are three test modes that can be used when performing a test: tension, compression, and
3-point bending.
Tensile Test - This test mode is used in combination with provided specimen grips. In this mode,
positive displacement is in the direction of increased fixture separation and tension forces are
positive.
Compression Test - This test mode is used in combination with provided compression platens.
In this mode, positive displacement is in the direction of decreased fixture separation and
compressive forces are positive.
The UniVert can be used in two configurations: vertical and horizontal (see Appendix D for
more details). The above test modes are all compatible in both configurations. For compression
and 3-point bend testing, test samples will need to be supported to meet the height of the platens.

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Software Overview
The software included with the UniVert device is called UniVert. It is divided into several
modules: a data collection module and an image review and analysis module as well as test
template review. The data collection module is used to set test parameters, enable specimen
loading and testing, and monitor test progress. The screen layout for this module is shown
below:
The image review and analysis module is used to playback accelerated or decelerated test
images, perform image analysis and tracking, and output movie files for presentation purposes.
The screen layout for this module is shown below:

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9
Output Files and Data Structures
For each test, the UniVert creates and saves three file types. The following table describes the
three file types for a project named “Sample1”. Output from this test would be found in a
“Sample1” output directory (a sub directory of the user specified data directory).
File Type
Description
.tst file
The Sample1.tst file that contains the exact protocol and settings used for the
test.
.csv file
The Sample1Data.csv file that contains comma separated numerical data such
as time, force, and displacement values.
.jpg files
Captured images such as Sample1.000010.3.jpg, which would correspond to
an image captured at 10.3 seconds from the start of the test.
Each test folder will also contain 2-3 subfolders. The “Logs” subfolder contains a text file of the
content of the text dialogue portion of the main screen (in the lower left-hand side). It is useful as
reference to troubleshoot problems with your system, should they occur as well as track test
progress.
The “Tracking” subfolder is initially empty. If tracking is done on any of the images in the test folder
using the “Analyze and Review” software module, there will be data files that contain the tracking
information stored in this directory.
The “Images” subfolder usually contains any recorded .jpg images from a test. These may also be
stored in the main data folder.
While using the “Analyze and Review” software module, you may create additional data files such
as text files (*.csv) containing tracking results, images with force data or tracking results overlaid
(*.wmf), or movie files (*.avi). These additional files can be stored in the test directory or elsewhere
on your computer’s main drive without interfering with the software application (once created, they
must be opened by 3rd-party software).
When working with the data, the user should be aware of a few details regarding the data output:
1. The output specimen size is based on the spacing between the grips or platens and does
not account for the specimen material outside of the test region.
2. The software cannot calculate stress since the thickness of the specimen is not known.
To calculate stress, you will have to manually measure the thickness of the material
before or after the test is performed and apply this measurement to the output force data
3. Strains can be calculated using the output displacement values (which are based on the
grip or platen motions). The specimen may actually be subjected to less strain than the
calculated values due to attachment site effects. The image tracking module is useful for
determining the actual strain values and variations within the specimen.

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10
Setting Up & Starting a Test
Overview
Step 1: Start a New Test
Step 2: Reset the Actuator
Step 3: Specify Test Type
Step 4: Zero the Load Cell (occasional)
Step 5: Modify the Test Parameters (optional)
Step 6: Mount the Specimen
Step 7: Execute the Test
Step 8: Terminate the Test Prematurely (optional)
Step 9: Saving the Template (optional)
If this is your first time setting up the UniVert system, please complete the steps in Appendix A:
Unpacking and Initial Setup prior to executing a test.
Step 1: Start a New Test
Launch the UniVert software and then select Collect New from the File menu.

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In the Create Test From Template dialog, perform the following steps:
1. Select a template that matches the type of test you wish to perform. See the below
UniVert Tip on how to select and use a template. You can modify the template
parameters in Step 5 below.
2. Name your test. The dialog will have a default test name. You can use the default or
rename the test. Each time you start a new test, the default name will continue to
increment the number at the end of the name (a 3 digit number).
3. If desired, you can change the location of the output data. The location of your output
data and images is determined by specifying a Test Name and Data Directory. The
template and data directories are user specific (computer login name). Each system user
can store their files to a different default location. The system uses the last location
selected as the default. Note that a local drive should always be used and data
transferred to network or cloud location after a test is complete.
Step 2: Reset the Actuator
We suggest performing a reset at the start of a new test session. This command sends the
actuator to its fully retracted position and resets the displacement value. If you have stopped the
previous test in mid cycle, then you should also reset the actuator. By resetting the actuator, you
are ensuring that the displacement measurements taken by the UniVert are accurate (dependent
on an accurate Zero Position Calibration –see System Calibration and Advanced Tools).
If you need to recalibrate the UniVert position, see the Zero Position Calibration or Custom
Position Calibration portion in the System Calibration and Advanced Tools section. This is
recommended if you are changing fixtures or configurations.
To reset the actuator, select Reset Actuator from the Tools menu, or press on the toolbar.
UniVert Tip: Selecting and Using Templates
How to create a Template: Designing an appropriate test sequence depends on both the type
of material being tested and the specific material properties you are interested in measuring.
When first testing a new material, you will have to experiment with the settings until the test
yields meaningful data.
The system comes loaded with sample templates to help you get started. Selecting a template
does not lock you into a specific test sequence or protocol –rather a template preloads a test
sequence and settings, all of which can be changed before a test is run.
Once you have developed a test sequence with settings that are appropriate for the material
you are testing, you should save these settings using “Save As Template” from the File menu.
You can then select this template the next time you initiate a test.
System Alert
You should NOT reset the actuator if the specimen is already loaded in tension. Doing so will
damage your specimen and/or the load cell.

UniVert User Manual
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Step 3: Specify Test Type
Access Test Mode in the Settings menu to select the appropriate test mode and install the
platens, grips, or 3-point bend attachments (see Appendix D for this procedure).
Step 4: Zero the Load Cell (occasionally)
While it is not necessary to zero the load cell with every test sequence, we suggest zeroing the
load cell at the start of a new test session. With repeated use, the zero point of the load cell can
drift. By zeroing the load cell, you are ensuring that the force measurements are accurate. The
force offset can also be affected by changing the fixtures.
To zero the load cell, select Zero Load Cell from the Tools menu or press on the toolbar.
System Alert
You should zero the load cell after attaching a platen or grip but before mounting a sample. If
a specimen is already loaded when the load cell is zeroed, the force reading will include an
offset load.

UniVert User Manual
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Step 5: Modify Testing Parameters (optional)
You can select and modify the parameters in the test sets by clicking on a row in the Test
Sequence table and then pressing the Edit Set button (or by double clicking on the desired row).
When you do so, the Set Parameter Editor dialog will appear.
Note that displacements are specified in either % strain, or mm. Force loads are specified in N,
and durations are specified in seconds.
The following table describes each of the parameters:

UniVert User Manual
14
Test Parameter
Description
Control Mode
Tests are performed under displacement or force control, however, you
can select the following control modes to achieve specific testing
objectives:
•For creep testing, use force control with a long hold duration.
•For stress relaxation testing, use displacement control with a
long hold duration.
Control Function
True Strain, Ramp, or Sinusoid is typically selected for tests performed
in displacement control mode. For tests performed in force control
mode, Ramp or Sinusoid controls are selected.
Stretch Magnitude
(Load Magnitude
when in Force
Control mode)
Selecting a stretch magnitude is dependent on the material you are
testing. A sound approach is to begin with a small magnitude and
iteratively move up to larger magnitudes.
If you are using Displacement control mode, you can specify the
displacement in either mm or as a percentage. For example, the
displacement on a 5mm specimen can be expressed as either 0.5mm
or 10%.
If you are using Force control mode, you can only specify the force in
N.
Watch the test results carefully to determine which magnitude setting
best achieves your test goals.
Preload
Preload is typically reapplied on every repetition during a
preconditioning set as well as on the first repetition of a testing set.
Specimen size is adjusted after a preload adjustment. Strain
calculations are based on the specimen size after the last preload
adjustment. If you are working with a material for which preload values
have been suggested, you can set the value accordingly. Otherwise,
zero is a good initial choice. The preload accuracy is directly influenced
by the resolution/accuracy of the load cell you are using.
Preload Magnitude
As with stretch magnitude, the preload magnitude settings depend on
the material you are testing. While Preload can be set at zero, typically
you would set the preload magnitude somewhere between zero and
10% of the peak load you expect to achieve.
Stretch Duration
For evenly spaced images, it is recommended to choose a number that
is an integer multiple of the Image Output Frequency.
Hold Duration
Hold Duration is typically set to 0, however it is useful for creep or
relaxation testing.
Recovery Duration
Recovery Duration is typically set to the same value as the Stretch
Duration.
Rest Duration
Rest duration is typically set to 0, however a non-zero value may be
used to mimic in vivo conditions or for specialized testing.
Repetitions
Apply enough repetitions until the force deformation curves from one
repetition to the next start to overlie each other.
Data Output
Frequency
Typically set to the same frequency as the image output frequency.
Image Output
Frequency
Typically set to 1Hz for cycles > 5 seconds and 15 Hz for cycles < 5
seconds.

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Step 6: Mounting a Specimen
Platen Mounted Specimens
1. Install the compression platens (see Appendix D for more details)
2. Place the specimen on the bottom platen.
3. Jog the top platen to the correct position using the jog arrows in Actuator Control
Alternatively, the Move Actuator to Specified Size command may be used. Ensure the correct
size value is entered before clicking .
UniVert Tip: Compression Specimen Mounting
Make sure to center the specimen on the platen as much as possible to ensure accuracy in
the force reading. Ideally, specimens will have two parallel flat sides and will make full contact
with both platens. Although this is not always possible, flat testing surfaces will improve force
distribution.