Project Specifications
WIRELESS REFLECTANCE PULSE OXIMETER
October 4, 2004
Team # 1
James Hart
Sofia Iddir
Rob Mahar
Naomi Thonakkaraparayil
Introduction and Overview
Pulse oximeters monitor blood oxygen content by measuring the absorption of light in an arterialized vascular bed. Since oxyhemoglobin and deoxyhemoglobin absorb light differently, the relative concentration of each blood component and thus the percentage oxygen saturation (Sp) can be determined by measuring absorbed light at two different wavelengths.
The objective of this project is to design a wireless reflectance pulse oximeter that would be available in the open market without a prescription for under $500. The primary function of the device is to enable parents to monitor the oxygen content of their children from any room in the house. In addition to infants and toddlers being the primary target, the product should be designed in such a way that it could be modified to further target a broader population such as athletes.
The final product will consist of a sensor module, a monitor and a beeper-likeportable alarm device. The sensor is to be placed on a peripheral tissue bed of the ankle, and will send data about the pulse rate and oxygen content via radio waves to the monitoring device which processes and displays the data. The monitor will then send the data to the beeper device that will also be able to digitally display it. An alarm will sound if an abnormal oxygen level, pulse rate and/or low battery is detected.
The basic design of a pulse oximeter probe contains red and inferred light emitting diodes (LED’s) and a photodetector. These components are arranged so that the LED’s illuminate a particular section of arterialized tissue and the detector collects the light from the LED’s which has been transmitted through the tissue section but not absorbed by the skin, bone, blood and other physiological absorbers. The steady state and time varying components of this signal are then used to calculate the fraction of the arterial blood which is oxygenated.
However, in this particular scheme, a reflectance pulse oximeter will be employed in order to ensure the immovability of the device when placed on the subject. The LED’s and a photodetector are therefore placed on the same tissue surface and the photodetector receives light which has been scattered from blood vessels within the tissue section. In addition, the sensor will always be in intimate contact with the subject’s skin in order to prevent light from traveling directly from the LED’s to the photodetector.
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Technical Specifications
ELECTRICAL PARAMETERS / Sensor / Monitor / AlarmDisplay / Minimum Number of Characters / 0 / 20 / 15
Minimum Height x Length x Width (Inches) / 0.5x2x1 / 2x6x3 / 1x3x1.5
Illumination / Visible under all lighting
Transmitter / Range (Feet) / Sensor→Monitor = 30 Monitor→ Alarm=100
Physical Path / Transmitted data must pass through obstructions
Voltage Input / 5 Volts
Voltage Output / 18 Volts
Power Input / 10 Watts
Power Output / 1.8 Watts
Current Capabilities / 100 Milliamps - 2 Amps
Harmonic Distortion / Sample Rate of 50 Hertz per Channel
Stability / Drop Test
Accuracy / 3%
Precision / 95% Confidence Limit of Less than 3%
MECHANICAL PARAMETERS / Sensor / Monitor / Alarm
Weight / Maximum Weight / 3 Oz / 2-3 Ibs / 4 Oz
On/Off Switch / Minimum Size (Inches) / / / 0.25x0.125 / 0.25x0.125
MATERIAL PARAMETERS
Materials / Non-irritant / Polymer / Polymer
Color / Color of Body / Blue/Pink / Black / Black
SOFTWARE / Sensor / Monitor / Alarm
Machine Dependent / Wait Times (Seconds) / 20 / / / /
Maximum Execution Speed / 2 . / 2 / 2
Termination/Restart / / / 1 Button / 1 Button
Visibility Distance (Feet) / / / 10 to 15 / 10 to 15
HOUSE KEEPING / Recharge after use or every 12 hours
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