Introduction and Overview
The medical field is always in need of appropriate engineering tools to aid in the solution of health problems. Advances in speed and less invasive procedures make the processes more efficient and less agonizing. One method that allows for such advancement is spectroscopy.
A proper definition of spectroscopy would be similar to something like “the study of molecular structure and dynamics through the absorption, emission, and scattering of light,”1 but spectroscopy is most often thought of as a method for gaining information about a substance by observing the effect that projected optical signals have when in contact with the particular substance. Medical applications suffer when a signal is degraded through absorption. Spectroscopic procedures using wavelengths around the 650 nanometer (nm) to 950 nanometer (nm) range allow for the least amount of absorption. That range is suitable to avoid water absorption and penetrate into blood in order to gather information concerning diseases and cancers.
Our solution to the problem is to use four laser light-emitting diodes to make tissue sample measurements. The system will use four laser light-emitting diodes to make tissue measurements. Each laser will produce a single wavelength, which will lie between between 650nm and 950nm. The laser diodes’ lights are channeled through a fiber optic cable so that the measurements can be remotely taken.
1 http://www.cobalt.chem.ucalgary.ca/ziegler/Wilson/spectroscopy/spintroformal.html
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| Project Statement .pdf |
| Project Specifications .pdf |
| Preliminary Proposal .ppt |
| Final Proposal Paper .pdf |
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Week 1: N/A Week 2: N/A Week 3: Group Held inaugural meeting with Quing Zhu. Week 4: Group held two meetings this week (Tuesday and Thursday) decided weekly meeting schedule. Began to get familiar with problem at hand. Week 5: Held second meeting with Quing Zhu. We discussed some problems with our understanding of the system at hand. We set up a yahoo groups account to manage team activities. Week 6: We acquired a digikey catalog and began devising a list of the different components we will need. At this point we broke the system down into distinct modules: Control Circuitry, Laser Circuitry, Modulation Circuitry, and Fiber optic/Mechanical couplings .We devised a technical diagram of the operation of the device in accordance to our given problem. Week 7: We decided on sending out our first order for supplies this included our first set of laser diodes and driver circuits. We ran into a roadblock concerning our modulation circuitry so we got to researching different methods of modulation. Week 8: While waiting for our first order to arrive we continued our search for different methods of modulation. We found out about crystal modulation decided to do further research on how to build a crystal modulation circuit. We were limited by the availability of supplies in the lab so we had to table the testing with crystal modulation techniques. Week 9: At this point we decided to break off the discrete parts of the system for individual development according to our personal strengths. Bryan: Assigned the task of designing the micro controller system which would pulse the lasers. Also assigned the task of figuring out the modulation of the lasers. Mike: Assigned the task of figuring out the laser and laser driver circuitry. Bill: Took on the task of designing the fiber optic coupling portion of the circuit. Week 10: Our first order arrived. Unfortunately we received two of the same orders so we had to send one back to digikey. Also a hindrance was our laser driver had no documentation we contacted digikey for a copy of a proper schematic. We then contacted the driver company themselves both attempts were unsuccessful. Week 11: Mike collected additional supplies from the fiber optics laboratory. He devised a plan for testing the specifications of the laser drivers we received. Bryan figured out the algorithm for the chase sequence necessary for the laser sequencing. Week 12: We started preparation of the final presentation and final paper. We finally figured out our laser driver type and schematic. Week 13: We met with Graduate student Yiwu Ding in the optics lab who assisted us in figuring out the direction we should take with the fiber optics portion of our system. Week 14: We finalized the presentation and proposal paper. Wrapped up semester business and sent out a final order for supplies. Week 15: The team worked on processing orders. Week 16: Worked on cleaning up modulation signal and bias-t. Checked-up on arrival of orders. Week 17: Decided to remove microprocessor from the system and replace it with CMOS or TTL chips. Looked for proper parts and contemplated overall system design. Week 18: The team talked to Anastacios and he helped us learn about working at high frequencies. It was decided upon to use lm555 timers in our design. We continued to look for parts and await the arrival of various parts. Week 19: Designed overall box layout and ordered a box. Week 20: Worked on a low-pass filter to clean up the modulation signal. Week 21: The Department was unable to process orders for two weeks. Worked on redesigning the sequencer. The team met with Professor Zhu. Week 22: Had to look up documentation for designing laser drivers and redesign it. Worked on the switch/power system. Week 23: Worked on smoothing out the modulation signal. Designed layout for the box. Attached the power supply to the box. Week 24: Designed relay circuit and built it. Tested relay circuit with sequencer and spent much time debugging. Drilled openings for LEDs in the front of the box and redesigned the box layout. Week 25: Continued work on the box. Put in much time getting the output of the modulation circuit to look nice. Worked on putting together laser diode boards. Week 26: Continued work on modulation and board set-up. Week 27:
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Electrical and Computer Engineering Department , University of Connecticut