Sleep Lab Monitor - Progress Report 10 11/07/08-11/14/08 Project Title: A combined Thermistor, Pressure, and CO2 device for use in the Sleep Laboratory Team Members: Jack Page – Team Leader [email protected] Nicole Daehn – Communicator [email protected] Lindsey Carlson – BSAC [email protected] Robyn Hrobsky – BWIG [email protected] Client: Christopher G. Green, MD Dept of Pediatrics School of Medicine and Public Health [email protected] 608.263.9608 Advisor: Willis Tompkins Dept. of Biomedical Engineering University of Wisconsin - Madison [email protected] 608.263.1581 Problem Statement: There are three measurements taken from each breath during polysomnography. The following devices are used: a thermistor to detect temperature difference between inhaled and exhaled air, pressure sensors that show a flattening pressure profile during upper airway narrowing, and CO2 sampling tubes to sense exhaled CO2. These three measurements are taken from two different devices placed under the child’s nose, with two prongs going into each nostril. This method can be inaccurate if a nostril was to become obstructed, and each device may not sample from both nostrils as well as the mouth. Moreover, the current apparatus may be uncomfortable for the child as well as insecure on the child’s face. This could cause a disruption of sleep and a possibility of the devices becoming unfastened during the night. To solve these problems, the goal is to design and develop a prototype that combines these three measuring devices into one apparatus that samples from both of the nostrils as well as the mouth, and attaches to the child in both a durable and comfortable fashion. 1Reinstatement of Team Goals from Last Week: 1. Test thermistors with specific temperatures by heating up water 2. Use the LabView program and custom circuit in conjunction with the water boiler and thermometer to test thermistors 3. Continue to tweak LabView program to ideal scale and try to record data in Excel spreadsheet 4. Continue making the mold for the attachment system 5. Pour the plastic into the mold to make the system 6. Acquire the heat shrink tubing Summary of Team Accomplishments: 1. Testing the thermistors a. Tested the surface mount thermistors. b. Figure 1 shows the waveform generated using the custom circuit c. The surface mount thermistors can not be tested in water i. Bigger thermistors can be because tape can be used to prevent a short ii. Since the surface mount thermistor is so small, nothing can be used to prevent a short Figure 1: Voltage vs. Temperature in time for surface mount thermistors 2. Decided to use surface mount thermistor for final prototype a. They are very small and thus will fit nicely on the cannula 2b. Great waveform obtained as shown in Figure 1 c. Superior stability in high humidity environments d. Excellent resistance stability during soldering 3. Testing the surface mount thermistors further a. We have designed a test using a heat gun b. This test will be used next week 4. Heat Shrink a. The heat shrink was ordered b. Three different sizes were ordered to fit the three different sizes of the cannula tubing c. 1/8 inches X 8 ft d. 1/4 inches X 8 ft e. 3/16 inches X 8 ft f. The tubes shrink to have of their original size 5. Attachment System Molding – Attachment pieces completed, shown in Figure 2 a. Molds were completing in the machine shop b. Pieces were screwed together c. Silicon was poured into the mold d. The pieces were completed a. There is a slit on the bottom of the pieces of plastic so they can slip over the cannula tubing Figure 2: Mold and plastic after pouring. Notice the two different diameters. 3Statement of Team Goals for Upcoming Week 1. Figure out the adhesive to use to secure the thermistors when they stick out of the heat shrink 2. Meet at the Bioinstrumentation lab for further testing of surface mount thermistors 3. Use LabView program to record data in excel using heat gun and surface mount thermistor 4. Get the heat shrink tubing 5. Split up the final paper among group members Project Schedule 9/5/08 – 9/12/08: Choose team and project, Meet Client, Get specifications for project 9/13/08 – 9/19/08: Develop PDS, Perform background research 9/20/08 – 9/26/08: Background research, preliminary design ideas 9/27/08 – 10/3/08: Continue to brainstorm for ideas 10/4/08 – 10/10/08: Work on design and choose design alternatives 10/11/08 – 10/17/08: Complete Mid Semester Presentations 10/18/08 – 11/27/08: Develop final design and complete prototype 11/28/08 – 12/12/08: Complete and give Final Presentation, submit notebooks and paper Team Difficulties: 1. Getting LabView program to record data points in Excel spreadsheet 2. Finding the GrassLead connectors to buy Expenses: 1. Surface mount thermistors 15 X $0.239/ea = $3.59 2. Lacquer coated thermistor disks 10 X $0.51/ea = $5.10 3. Bead/pearl shaped, ethoxyline resin coated thermistors 10 X $0.333/ea = $3.33 4. Other disk thermistors 10 X $0.277/ea = $2.77 5. Surface mount coin shaped thermistors 10 X $0.21/ea = $2.10 6. Heat shrink 1/8 IN X 4FT clear 8 ft for $2.16 7. Heat shrink 1/4 IN X 4FT clear 8 ft for $3.26 8. Heat shrink 3/16 IN X 4FT clear 8 ft for $2.62 45 Total thus far = $24.93 Activities and Individual Accomplishments: Advisor Meeting 11/7: 1 hour Team meeting 11/9: 1 hour - Met to order heat shrink Team meeting 11/12: 3 hours - Met to test thermistors Other: Nicole – 5 hours: Researched heat shrink, updating notebooks Jack – 5.5 hours: Progress report, researched heat shrink, updating notebooks Lindsey – 6 hours: Updated LabView program, updating notebooks Robyn – 5 hours: Updated website, updating notebooks Total hours for this week: 26.5 hrs Cumulative hours to date: 204.5 hrsSleep Lab Monitor Gantt Chart Fall 2008 Completed: In Progress/Planned: 9/5 9/12 9/19 9/26 10/3 10/10 10/17 10/24 10/31 11/7 11/14 11/21 11/28 12/5 12/12 Propose project Background research Client Meetings Meetings with Professors/Techs Develop PDS Brainstem design ideas Design alternatives/matrix Midsemester presentation work Finalize design ideas Ordering materials process/research Construct prototype
View Full Document
Unlocking...