Archive from the Fall 2001 semester.

Week 9 E-mail Progress Report

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Thermal warm/heat probe for neurological examination

Team members:

Andrew Hoyord
Bern Jordan
Dana Mueller
Paul Thottakara
Paul Victorey

Client:

Miroslav Backonja

Reporting period:

11/1/01 - 11/7/01

Problem statement:

"Doctors are now finding it necessary to test patients experiencing pain or numbness primarily in their extremities, and possibly the trunk or face for neurological damage and warm/heat sensitivity by applying hot sensations to their skin. A device that heats up to target temperatures of 38 and 45 degrees Celsius relatively quickly, and is able to be used many times per charging of the handle is preferred. This device would be an attachment to the already existing battery operated portable and wall mounted Welch-Allyn ophthalmoscope/otoscope handle."

Restatement of team goals:

1. Complete design and validation of thermistor circuit so it will interface correctly with the ADC we have chosen.
2. Test the ADC for correct conversion of known voltages.
3. Test probe prototype for temperature swings on voltage steps.
4. Design and test algorithm to perform timing with the microprocessor.

Accomplishments:

1. Programming of the microprocessor now in v0.5, program loops always take the same amount of time to ensure good accuracy when using the loops to implement timing.
2. The problem of the analog circuit providing false output for too low of temperature fixed ~ the temp at which this occurs is far below the expected lowest operating temperature.
3. Prototype circuit testing coming along well.
4. Found experimentally the temperature peaks and valleys when our control algorithm is implemented. The swings are with our maximum tolerances.

Goals for next reporting period:

1. Research a way to implement the timer with a skin switch.
2. Implement and test timing with the µP, using a momentary switch to start the timer.
3. Use the µP to control temperature in our probe prototype, measuring accuracy.
4. Bringing all team members up to speed on the program used to control the µP, so we can all effectively critique it for changes.
5. Contact client about human subjects testing.
6. Add a filter to the analog circuitry to reduce the error of the ADC voltage conversion.

Project schedule:

Past
9/7 - 9/12: Assigned roles to team members and met as a group to discuss project goals and tasks.
9/13 - 9/19: Housecleaning of old project materials. Tested probe for heating characteristics.
9/20 - 9/26:
9/27 - 10/3: Investigated a microprocessor kit to use in device. Tested new Welch-Allyn battery to see how powerful it is, compared to the old battery.
10/4 - 10/10: Tested probe prototype for its power requirements at each target temperature.
10/11 - 10/17: Prepared mid-semester presentation. Thinking about how to use microprocessor. Made CAD drawings of power handle.
10/18 - 10/24: Mid-semester presentation in class, 10/19. Continued learning about microprocessor. Divided team to work in parallel on separate parts of the project.
10/25 - 10/31: Continued programming microprocessor. Began design of thermistor circuit. Found Op Amp and ADC that will function with a single supply voltage. Testing components that make up the thermistor circuit.
11/1 - 11/7: Thermistor circuit design completed, circuit constructed and tested for correct operation. Found probe temperature swings upon cutting and adding power when the temperature rises or falls through each of our 2 target temps.

Future
11/8 - 11/14: Add filter to the analog circuit to reduce error in voltage conversion. Test entire prototype, analog and digital parts together. Revise design and µP program as necessary.
11/15 - 11/21: Continue testing and revisions.
11/22 - 11/28: Construct next generation prototype.
11/29 - 12/5: Design connection to the Welch-Allyn handle. Begin work on final reports.
12/5 - 12/11: Make handle connection piece and implement device on the handle. Prepare final reports and final design presentation.
12/12 - 12/18: Final Design presentation. Attend final design meeting.

Difficulties thus far:

none

Activities:

Total time (this period):

18.0 hours

Total time (overall):

155.5 hours

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