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A skin color monitor that records color changes every 10 seconds that occur during hot flashes, which could be used to provide the objective measurement needed for therapeutic drug testing of menopausal women. The device is to be capable of discerning color changes while remaining small (6 x 6 x 2)cm or smaller and at a low cost (under $200). A 525 nanometer wavelength LED will shine light onto the skin and a photodiode registers the change in reflectance due to blood flowing into the skin. This lowers the output voltage by 5 to 7 mV. The changes in the voltage are recorded every 10 seconds. In the future, the device will adhere to the skin in the upper chest region. Also, the circuit will be printed on a miniature circuit board and the electronics will be integrated into the housing.
From left to right: Grant Smith (BWIG), Vince Mi (Leader), Brooke Sampone (Communicator), Amy Lenz (BSAC)
The final design incorporates a green LED and a photodiode into the reduced housing (2.5 x 2.5 x 1.5)cm. The circuit is currently external and incorporates an inverting amplifier with a gain of 13.3 and a low pass filter to exclude measurements on orders less than 1 Hz. It can repeatably and reliably measure skin color changes due to induced redness in a variety of skin tones.
| Week | Reporting Period Beginning | Activities |
|---|---|---|
| 1 | September 5 | Selected Project, First Advisor Meeting, Scheduled Client Meeting, Began Research |
| 2 | September 12 | Continued Research, Began Brainstorming, Met with Client, Met with Previous Design Team Members, Posted Website |
| 3 | September 19 | Finalized PDS, Constructed Circuit, Discovered Problems Regarding Noise and Light Filtration in the Device Itself |
| 4 | September 26 | The team met with Kevin Eliceiri and gained lots of knowledge from Kevin’s experience with LEDs, along with a list of contacts and suppliers that may help us. The team worked on the existing circuit to try to get the necessary gain. |
| 5 | October 3 | The team purchased LEDs and began preparing the power point presentation. |
| 6 | October 10 | The mid semester oral presentation was completed and performed. |
| 7 | October 17 | The mid semester paper was completed. |
| 8 | October 24 | Circuit and sensor runs with correct gain as verified by preliminary testing. |
| 9 | October 31 | Figured out what was wrong up with the circuit. Turns out the multi-meter was set up incorrectly, so we adjusted the gain on the amplifier appropriately |
| 10 | November 7 | Constructed two possible housing prototypes and purchased photodiodes. |
| 11 | November 14 | Tested to monitor skin color changes using a phototransistor as last years group did, but the readings were fairly unrepeatable from minute to minute. |
| 12 | November 21 | Finished the housing construction and tested the device using a photodiode and a phototransistor and determined that the photodiode was far more reliable in providing repeatable outputs. |
| 13 | November 28 | Completed testing, constructed a poster and gave a presentation about the final product and the work leading up to it. |
| 14 | December 5 | Finished final report and notebooks and met with advisors to discuss the content of the class and the future of the course at UW Madison. |
| 15 | December 12 | The project was ended and we went home. |
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Project Design Specifications (Sep 21 2008, 44 kb) |
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Mid Semester Presentation (Oct 17 2008, 1559 kb) |
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Mid Semester Report (Oct 24 2008, 776 kb) |
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Final Poster (Dec 8 2008, 1546 kb) |
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Final Design Report (Dec 12 2008, 2549 kb) |
