October 12th Meeting
Meeting Goals - Get Dale caughtup on progress
- Review Project Learning
- Plan to move forward
Agenda 1. We'll start out by reviewing what we've gotten done up to this point - We've got a set of specs on the website
- Contacted Doctor Frostad
- First prototype build
- IEC Regulations
- Contact from SIDS Organization
2. Next up, we'll talk about this last week - Trip to the Sleepcenter
- 2nd Prototype Build
3. Then, we'll review our project learning goals for this last week by having each team member give a short presentation on thier research. 4. After we get though that, we'll make sure to give feedback, and assess what where we are at. 5. Lastly, we'll review our next prototype plans - we may do 2 in parallel for the 2 weeks depending. 6. Then, we'll talk about how we are going for our project to complete the conceptual design process.
Minutes SIDS Monitor Team Meeting #5. 10-12-06 3:33pm I. Report on Prototype #2 A. The purpose of the second prototype was to confirm a change in pressure inside of an air mattress when exposed to an external force. B. Translucent tubing was partially filled with water and connected to the inflated air mattress. The water level in the tube would then change as a result of applied pressure on the mattress. C. Applied pressure on the mattress produced a large change in the water level compared to the change of impedance sensed by a similar amount of pressure on prototype #1. D. Little change in water level resulted from an adult lying on the mattress and breathing normally. Note: a leak in the mattress was noticed once it was laid on.
II. Report from Field Trip to the Gritman Sleep Center A. Piezoelectric chest straps are very commonly used in sleep centers to monitor patients with apnea. Apnea is defined as stopped breathing for 10 or more seconds while sleeping. B. Pulse oximeters are another commonly used sensor. C. The technicians’ monitoring preferences are ordered as follows: 1. Piezoelectric sensing 2. Heart rate monitor 3. Pulse oximeter 4. Face mask to sense air flow.
III. Sensor Research. A. Skin temperature/moisture sensors -Lloyd (mentor) 1. Moisture sensors are cheap (low as $15) and considerably accurate. -If secondary research shows SIDS to relate at all to shock, we should be able to expect an increase in skin moisture during the onset of SIDS.
2. Temperature sensors may be ineffective for our purposes.
B. Pulse Oximetry - Lloyd (team leader) 1. Uses a dual LED and single photoelectric diode emitter/collector system to measure the oxygen saturation level in the blood. 2. The sensor should be connected to an area of somewhat translucent skin; typically to the infants’ foot. 3. The sensor is typically programmed to take a set of readings every five milliseconds. This can be changed for our purposes.
4. LED lights are specified to last 100,000 hours. 5. Setbacks include: - Prolonged exposure to the infared beam can possibly cause the equivalent of a sun burn. - Darker skin will absorb more light, effectively reducing it’s translucency. (Not a big problem). - The sensor can not differentiate between oxygen and carbon monoxide.
C. Motion sensing devices. - Chris 1. Motion sensing camera unit. -Operates on sensing changes in pixel data from a camera image. - Chest movement from a sleeping baby will most likely give too low of a signal if any.
2. Digital weight scale - Should be effective at measuring minute changes in pressure.
D. Heart rate sensor - Bart 1. Attach to chest. 2. Medical versions are very expensive. Recreational version can be decently cheap.
E. Respiratory Impedance - Colby
1. Four sensors are connected to the outer edges and central region of the patients’ thorax. Chest movements from breathing cause impedance changes between the sensors. 2. There is also a version that operates on measuring changes in inductance.
H. CO2 Sensors. Infared and chemical - Jeff 1. Infared CO2 sensors utilize a infared light emitter/collector system. -Gasses diffuse into light tube, the collector measures the amount of light that the gas absorbs and is programmed to recognize the characteristic level of absorption from CO2. -These are most common but require more power to operate than the chemical sensors.
2. A chemical sensor developed in the Netherlands uses a hydrogel film to become stiff in response to the pH change of an electrolytic material. The pH changes in the presence of CO2. The stiffened hydrogel would then apply force to a pressure sensor.
I. Thermal Imaging - Jen 1. Utilizes expensive cameras. 2. Would use method of analyzing changes in pixel data similar to the motion sensing cameras. 3. It inspires the idea to use a blanket or shirt/bag which would be covered in spots made of a material that an overhead camera could easily detect. Tracking the change in distance between dots could give information about the infants’ breath patterns.
IV. Comments from Don A. We need to work on find existing products and compare them to our needs. B. Designing a prescription device should not be discounted as an option, just discouraged. C. Include dated diagrams with descriptions in the log books as well as photos. D. Incorporate mathematical models into the prototyping process. E. We’re doing good, keep up the energy!
V. For next week. A. Two prototypes to be developed 1. Chest movement monitoring through induction measurement. -Lloyd, Jen and Jeff
2. Digital Scale sleeping surface to measure pressure changes caused by inhalation/exhaling. -Colby, Chris, Bart
VI. Action Items A. Bart will talk to Dr. Budwick Friday 10-13 to gain insight about modeling equations. B. Jen and Bart will talk to Dr. Frosted (Pediatrician) Friday 10-13. C. Chris and Jeff will go to the schematic workshop on Tuesday. Bart and Lloyd will go to the Axiomatic workshop and Colby will go to the MS Project Design workshop. D. Chris and Colby will check with our client Dale about the video conference equipment that he has access to.
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