Skin Color Monitor

Sarah Offutt, Rachel Mosher, Victoria Vasys

BME 301March 7, 2008

Client:John Webster, Ph.D

Department of Biomedical Engineering

Advisor:Brenda M. Ogle, Ph.D., M.S.

Dept. of Biomedical Engineering

Overview Problem Statement Background

Physiology of Hot Flashes Existing Devices

Design Components Housing Design Clear Plate Circuit

Future Work Questions

Problem StatementThe goal is to design a device to monitor

skin color changes during hot flashes, which could be used to provide the objective measurement needed for therapeutic drug testing for menopausal women.

Physiology of Hot Flashes Decreased estrogen levels confuse

hypothalamus- body is “too hot” Due to menopause, medications

Heart pumps faster, blood vessels dilate, blood flow to periphery increases Skin flushes red

85% of women experience hot flashes during menopause Sweating, sleep loss, interruption of daily

activities

Existing Devices Temperature Sensors Skin conductance measurements Skin-color-change detectors We aim to merge the two technologies in

order to best detect hot flashes Longer lasting Easier use

Last Semester Blue LED and Phototransistor Would like to improve on

Specular Reflection elimination Smaller Larger color differentiation

PDS Summary Measurements taken every 10 seconds 6 x 6 x 1 cm 50 g Battery life to last for overnight reading Comfortable and discreet

Housing Design

Needs: Aesthetics Durability Space for circuitry Comfort

3 options Box Flat Box Dome

Housing Design MatrixCRITERIA WEIGHT Box Flat Box Dome

Aesthetics 25 0.1 (2.5) 0.4 (10) 0.5 (12.5)

Durability 25 0.37 (9.25) 0.33 (8.25) 0.3 (7.5)

Space for LEDs and Circuitry 25 0.33 (8.25) 0.33 (8.25) 0.33 (8.25)

Comfort 15 0.2 (3) 0.35 (5.25) 0.45 (6.75)

Machinability 5 0.5 (2.5) 0.4 (2) 0.1 (0.5)

Cost 5 0.2 (1) 0.4 (2) 0.4 (2)

TOTAL 100 26.5 35.75 37.5

Clear Plate Skin kept flat Even pressure Needs to be:

Transparent Lightweight Safe

3 options NOA61 Acrylic Glass

Clear Plate Design Matrix

CRITERIA WEIGHT NOA61 Acrylic Glass

Safety 35 0 0.7 (24.5) 0.3 (10.5)

Weight 25 0.3 (7.5) 0.5 (12.5) 0.2 (5)

Cost 15 0.1 (1.5) 0.4 (6) 0.5 (7.5)

Refractive Index 15 0.3 (4.5) 0.3 (4.5) 0.6 (9)

Machinability 10 0.2 (2) 0.5 (5) 0.3 (3)

TOTAL 100 15.5 47 35.5

Circuit 3 options

Original Design Parallel Branch Design Op-Amp Design

Want circuit that will detect the smallest amount of change

Will make biggest difference in quality of project

Circuit Design 1 and 2 Circuit 1—Original

Few circuit parts Low cost Easy to construct Lowest voltage output

Circuit 2—Parallel Few circuit parts Low cost Easy to construct 0-5V output range

Circuit Design 3 Op-amp

More circuit parts Increased cost Harder to construct Offset resistor Ranges -5 to 5V

Circuit Design Matrix

CRITERIA WEIGHT Old Circuit Parallel Branch Circuit Op-Amp Circuit

Differentiation 50 0.1 (2.5) 0.2 (5) 0.7 (17.5)

Ease 20 0.4 (10) 0.4 (10) 0.2 (5)

Size 20 0.4 (10) 0.4 (8) 0.2 (4)

Cost 10 0.4 (4) 0.4 (4) 0.2 (2)

TOTAL 100 26.5 27 28.5

Final Design Blue LED Phototransistor Dome housing design Acrylic Plate Op-amp Circuit

Current Work Specular reflection eliminated Tested different colors of “skin” Compared different colors of LEDs Phototransistor compared with photocell Housing will be made soon

Future Work Design Circuit

Finding skin color output range Setting offset Testing skin color values with exercise

Making Independent Print Circuit -5 to 5V source Recording device

Implement Housing Design

References Carpenter, J. S., Azzouz, F., Monahan, P. O., Storniolo, A. M. &

Ridner, S. H. (2005). Is sternal skin conductance monitoring a valid measure of hot flash intensity or distress? Menopause, 12(5), 512-9.

Raskin, B. (1987). Hot Flashes. New York: St. Martin’s Press. Singh, M. & Simpkins, J. W. (Eds.). (2005). The future of hormone

therapy : what basic science and clinical studies teach us. New York: New York Academy of Science.

Wearable hot flash monitor (WHFM). Metis Design Corporation. Retrieved February 17, 2008 from http://www.metisdesign.com/biosensors.htm.

Webster, J. G., Bahr, D. E., Shults, M. C., Grady, D. G. & Macer, J. (2006). A miniature sternal skin-attached hot flash recorder. International Federation for Medical and Biological Engineering, 14, 577-580.

Questions