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. Conduct phantom experiments Design skin-friendly stretching apparatus Develop systematic method of testing skin forces

Skin Cancer Types of skin cancer Basal Cell carcinoma ~800,000/yr Squamous cell carcinoma ~200,000/yr Melanoma ~60,000/yr Most aggressive Originates in melanocytes Moles Types: Normal and Atypical Size: 2 mm-2 cm Depth of melanoma: 1 mm- >4 mm Color: pink-purple Increasing Rate of Incidence and Morbidity : 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

Current Methods of Detection Clinical eye Accuracy varies with experience Biopsy Dermoscopy 10X magnification, liquid polarizing lens Only ~75-80% accurate Serial photography Software expensive (~$30,000) Slow Specialty clinics In vivo confocal microscopy Experimental

Cost of Treating Skin Cancer Physicians Lab fees Time Resources 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 Insurance Companies Cost Annual mean charged to Medicare: NMSC: $357 million Melanoma: $107

Our Proposed Device Safe Easy Non-invasive Quick Effective Cost-efficient

Using plexiglass box: Overhead view 130 mm 25.4 mm Lead screw Force Sensor Voltmeter

Design Feedback Meeting with Phil Davis Lead screw  Linear Actuator Use SolidWorks Contact Dr. Goldfarb for rapid- prototyping Portescap Representative Use a control board for the linear actuator

Using plexiglass box: Overhead view 130 mm 25.4 mm Force Sensor Voltmeter Linear Actuator

SolidWorks Schematic Linear Actuator Force Sensor Translational Motion Camera

Digital Linear Actuator Generate controlled physical linear displacement Linear step resolution-.001” Unipolar coil construction Power consumption- 2.5 Watts

Design Specifications: Ultra-Low Profile Load Cell - S215 Strain Gauge Technology Measures up to 8 N (2 lb-force) Dimensions: x 5.99 mm (1.1 x.236 in) Rigidly mounted on beam

Budget Force Sensor $ Linear Actuator $ M Micropore Surgical tape $10.00

Testing Methods Uniaxial Tension Simple Finite Element Method Viscoelastic parameters of the skin Independent Testing with the Bose ElectroForce © Elastography electroforce.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… Requirements: 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 Side view 4mm 1cm 2cm 5mm Vytaflex-10 Vytaflex-60

Sketch of the Grip Design Thread to transducer Thread to translation part of the tester clamps Top view

Alternative Solution… Buying customized grips from Cost: $4,000

Independent Testing with the Bose Electroforce © 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 February 9: Received materials for independent testing February 24: Ordered force sensor and linear actuator March Begin independent testing (compression/indentation) Submit SolidWorks design for prototyping March Complete independent testing Begin testing our device March Comparative analysis using Dr. Miga’s model April Finalize results; prepare for design presentation

References M. I. Miga, M. P. Rothney, J. J. Ou, "Modality independent elastography (MIE): Potential applications in dermoscopy", Medical Physics, vol. 32, no. 5, pp , 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 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

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