Transcript 02/28/07 Oral Presentation #4

A Novel Dermoscopic Probe for Determining
Elasticity Measurements of the Skin
Group 7:
Erica Bozeman
Markesha Cook
Stephanie Cruz
February 28, 2007
Design Objective
"Structural alterations within cancerous skin-lesions cause unexpected
patterns of anatomical deformation in response to mechanical forces."
Dr. Michael Miga
Hypothesis
If structural alterations in skin cancer lesions differ from that of normal skin
when a mechanical force is applied, then a systematic method of measuring the
force response of a skin lesion can be compared to that of normal skin to
determine the if the presence of skin cancer.
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Conduct phantom experiments
Design skin-friendly stretching apparatus
Develop systematic method of testing skin forces
Skin Cancer

Types of skin cancer
 Basal Cell carcinoma

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Squamous cell carcinoma

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~200,000/yr
Melanoma
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~800,000/yr
~60,000/yr
Most aggressive
Originates in melanocytes
Moles
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Types: Normal and Atypical
Size: 2 mm-2 cm
Depth of melanoma: 1 mm>4 mm
Color: pink-purple
http://www.aad.org/aad/Newsroom/2005+Skin+Cancer+Fact+Sheet.htm
•Increasing Rate of Incidence and
Morbidity
•1973-1995: incidence increases
from 5.7/100,000 to 13.3/100,000
•Adults over 65 account for large
percentage of new cases: males
(22%) females (14%) but only
make up ~ 5.2% of population
•Poor incorporation of technology
•Underused methods of
screening
www.abc.net.au/science/news/img/melanoma.jpg
Current Methods of Detection

Clinical eye
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Dermoscopy
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10X magnification, liquid polarizing
lens
Only ~75-80% accurate
Serial photography

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Accuracy varies with experience
Biopsy
Software expensive (~$30,000)
Slow
Specialty clinics
In vivo confocal microscopy

Experimental
www.dermafend.com/images/illust/abcds_larger.jpg
http://www.jfponline.com/images/5206/5206JFP_AppliedEvidence-fig4.jpg
Cost of Treating Skin Cancer
Patients
•Discomfort
•Uninsured costs
•scarring
•time
•Cost of treatment
Physician’s office: $492
Inpatient: $5537
Outpatient: $1043
•Melanoma
•$740 million/yr (US)
•Advanced: $168,000
•Early treatment: $1800
•Screening $700
Physicians
•Lab fees
•Time
•Resources
Insurance
Companies
•Cost
•Annual mean charged to
Medicare:
NMSC: $357 million
Melanoma: $107
Our Proposed Device

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Safe
Easy
Non-invasive
Quick
Effective
Cost-efficient
Using plexiglass box:
Overhead view
130
mm
Force Sensor
Voltmeter
Lead
screw
25.4
mm
Design Feedback

Meeting with Phil Davis

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Lead screw Linear Actuator
Use SolidWorks
Contact Dr. Goldfarb for rapidprototyping
Portescap Representative

Use a control board for the linear
actuator
Using plexiglass box:
Overhead view
Linear
Actuator
130
mm
Force Sensor
Voltmeter
25.4
mm
SolidWorks Schematic
Camera
Linear
Actuator
Translational
Motion
Force Sensor
Digital Linear Actuator

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Generate controlled
physical linear
displacement
Linear step resolution.001”
Unipolar coil
construction
Power consumption2.5 Watts
Design Specifications:
Ultra-Low Profile Load Cell - S215

Strain Gauge Technology
Measures up to 8 N (2 lb-force)

Dimensions:
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27.94 x 5.99 mm (1.1 x .236 in)
Rigidly mounted on beam
Budget

Force Sensor
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$155.00
Linear Actuator

$55.00
3M Micropore Surgical tape

$10.00
Testing Methods

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Uniaxial Tension
Simple Finite Element
Method
Viscoelastic parameters
of the skin
Independent Testing
with the Bose
ElectroForce ©
Elastography
http://www.boseelectroforce.com/product.cfm?pid=41&sid=1
Phantom Skin: Vytaflex-10 and
Vytaflex-60

Approximate difference between
Elastic modulus is 6 x’s.

Tensile strength: 160 psi

Elongation at break: 1,000%
Challenges We are Facing…
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Requirements:
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Clamps must be
lightweight
Must mate perfectly with
the tester
Need to keep weight
symmetric about the
centerline in all directions
One side of the clamp
should not weigh more
than the other side
Preparation of the Phantom
Skin
Sample shape – 4 mm thick.
Top view
5mm
1cm
2cm
1cm
Vytaflex-60
Side view
4mm
Vytaflex-10
Sketch of the Grip Design
Thread to translation
part of the tester
Thread to
transducer
clamps
clamps
Top view
Alternative Solution…
Buying customized grips
from
www.bose-electroforce.com
Cost: $4,000
Independent Testing with the Bose
Electroforce ©
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Assumption: Skin exhibits
linear elastic properties
Compression testing and
Indentation testing instead of
tensile due to accessibility
Determine the viscoelastic
properties of the skin such as
the Young’s modulus,
Poisson’s ratio and the plane
stress.
Compare these to the values
that result from our probe
testing.
Future Matlab Processing
Important Design Dates

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February 9: Received materials for independent testing
February 24: Ordered force sensor and linear actuator
March 11-17
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March 18-24
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Complete independent testing
Begin testing our device
March 25-31
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Begin independent testing (compression/indentation)
Submit SolidWorks design for prototyping
Comparative analysis using Dr. Miga’s model
April
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Finalize results; prepare for design presentation
References
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www.skincancer.org
http://www.eurekalert.org/pub_releases/2006-10/osoa-ltt101606.php
http://www.smdsensors.com/detail_pgs/s100.htm
http://www.omega.com/literature/transactions/volume3/strain.html
M. I. Miga, M. P. Rothney, J. J. Ou, "Modality independent
elastography (MIE): Potential applications in dermoscopy", Medical
Physics, vol. 32, no. 5, pp. 1308-1320, 2005.
Tsap, Leonid V. et al. Efficient Nonlinear Finite Element Modeling
of Nonrigid Objects via Optimization of Mesh Models. Computer
Vision and Image Understanding. Vol 69, No. 3 March 1998 pp. 330350.
Wan Abas, W.A.B and J.C. Barbenal. Uniaxial Tension Test of
Human Skin In Vivo. J. Biomed. Engng. Vol 4 January 1982 pp.6571.
Questions