Visual Alarm System for Ohmeda Biox 3700 Pulse Oximeter Alex Choe Rohit Mittal Advisor: Dr. Walsh, Dr. Linstrom

Ohmeda Biox 3700 Pulse Oximeter Project proposed by Dr. William Walsh Neonatologist / Chief of Nurseries; works in the Neonatal Intensive Care Unit (N.I.C.U) Our technical advisor is Dr. Dan Linstrom Research Professor in the Medical Center

Why did he propose this project? Pulse Oximeter measures the pulse rate and oxygen saturation rate of a new born baby The medical device sounds an alarm when the measured oxygen saturation rate goes below the lower limit (50~60%) However, it is believed that this device makes loud audible alarms and is detrimental to the health of the patients.

Objectives of the Project Silence the audio alarm Build and modify the circuitry of the alarm in the Ohmeda Biox Pulse Oximeter to replace the audio to visual alarm.

Silencing the Audio Alarm There are three possible pathways: 1. Turn down the volume on the alarm 2. Disconnect the alarm altogether 3. Install a switch between the audible and the visual alarm

Audio Alarm Circuitry The open end is the normal input to the speaker with the following values: V(max) = ~2V I(max) = ~2 mA [V(out) from speaker: 0.45V]

LED Driver Circuitry Once through the driver the values change as follows: V(out) = ~2V I(out) = ~3mA R = 1 kohms

Future Directions Simple movements set off the alarm A way to compare the digital outputs and eliminate false alarms Complications relating to USB-port/RJ-45 connections (ref. Nuts and Volts, April ‘00) Networking problems of such connections