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Comprehensive Health Monitoring System . Group #5 Samuel Rodriguez Daniel Thompson Chadrick Williams Giselle Borrero. Sponsored by: Dept. of Veterans Affairs. Project Description. Wireless monitoring pulse oximeter, blood oxygen concentration (SpO 2 ) and fall detection
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Comprehensive Health Monitoring System Group #5 Samuel Rodriguez Daniel Thompson Chadrick Williams Giselle Borrero Sponsored by: Dept. of Veterans Affairs
Project Description • Wireless monitoring pulse oximeter, blood oxygen concentration (SpO2) and fall detection • Consists of four units • Receiving Display unit (RDU) • 3 Transmitting Sensor Units (TSU) • All units will be worn by the patient • Finger sensor will obtain pulse and SpO2 and transmit • Chest and thigh sensor will determine patients posture information • Waist display will receive data, display data, and transmit emergency signals
Goals • Ultimately to monitor patients for chronic heart and related health conditions • Remotely contact emergency services • Provide location to emergency services of patient • More affordable than existing wireless units • Ideal for a variety of users • Maximum protection at minimal to no cost
Objectives Transmitting Sensor Units (TSU) • To be worn on the finger, wrist, chest and right thigh • Battery powered • Control the pulse oximeter sensor • Make calculations to achieve pulse and oxygen concentration data • Determine the posture of the patient • Measure patient’s angular velocity and acceleration • Monitor unit’s battery life • Transmit data wirelessly to the waist unit (RDU) Receiving Display Unit (RDU) • Receive data wirelessly from TSUs • Display patient’s pulse and oxygen concentration • Contact emergency services • Monitor unit’s battery life • Audible and visual alerts for critical conditions, loss of signal and battery life, and display personal information
Physical Layout Chest Unit Hand Unit Waist Unit Thigh Unit
Pulse Oximeter • Non-invasive optical measurement of heart rate and blood oxygen saturation • Hemoglobin is the red colored substance in blood and is the carrier of oxygen • Red and infrared light are attenuated less by the body tissues and more by blood (600nm, 940nm) • Light shines through finger and strikes a photodiode, which creates a very small current based on the amount of light incident on the photodiode • This determine attenuation of light based on the output of the photodiode
Pulse Oximeter Design • Sensor • Generate alternating pulses of light at 600nm (red) and 940nm (infrared) • Photodiode must detect light in the range of 600nm to 940nm • Convert photodiode current to voltages values between 0V to 2.3V • Accuracy of ±2% (70% - 100%) • ±2 BPM for pulse • Transmit a maximum of 10 ft • MCU • Two DACs 12-bits • Three ADCs 12-bits • 12 GPIOs
Pulse-Ox Sensor • To calculate pulse oximetry the photodiode current must be converted to a voltage • This voltage has both a DC and AC component that represents attenuation of light • DC-constant volume of blood used for auto gain control • AC – ebbing and flowing of blood used for measurements
Sensor Control • Control alternating pulses by pair of LED select lines (STG3155) • Common power lines • DAC controls current through system to avoid damage to LEDs
Automatic Gain Control • MCU determines DAC output based on DC component input • Utilizes constant DC equation because the DC component from the red and infrared LEDs must be the same • AGC constantly monitors output from diode and adjusts to maintain the same voltage • Co is the concentration of oxyhemoglobin (Hb02) • Cr is the concentration of reduced hemoglobin (Hb) • is the absorption coefficient of Hb02 at wavelength • is the absorption coefficient of Hb at wavelength
Chest and Thigh Fall Detection Design • Determine the patient’s position (sitting, standing or laying down) • Measure angular velocity and acceleration of patient • Have a range of ±6g acceleration. • Have an accuracy of angular velocity between ±300˚/s to ±500˚/s • Have a sampling rate of at least 120Hz
Fall Detection Design • Consist of: • Two 3-axis gyroscopes (ITG-3200) • Two 3-axis accelerometers (MMA7631L) • One of each in the center of the chest and right thigh • MCU MSP430FG438 • Three 12-bit ADCs • 34 GPIOs • RF TransceiverCC1101
RDU Design • RF transponder receives information from peripheral units • Multicontroller stores past data and makes decisions about patient status • 16x2 LCD displays patient information, alerts, emergencies, or system status • Buzzer and LEDs provide visual and auditory stimulus for alerts
Liquid Crystal Display • Separate unit from the MCU • Built-in display controller • May display pulse, blood oxygen content, patient’s name, or alarm information
Alert Protocol • Green LED- Blinks if a fall is detected • Blue LED- Blinks if RDU loses signal from peripherals • Red LED- Blinks if emergency is active or user has indicated panic • Piezoelectric Buzzer- Pulses if emergency is active
Power Management • All units powered by a battery, through a DC/DC buck converter • 3.3V supply to MCU, RF transceiver, and all sensor units • 5V supply to LCD • Battery voltage monitored by built-in comparator in the MSP430FG43x
Buck DC/DC converter • 3.3V output supplies MCU and sensors, directed through another buck converter to upgrade to 5V for the LCD anode
Battery Life Monitoring • Analog comparatorinternal to MCU • Output to Red-Yellow-Green LED • Voltage divider from battery, scaled with the MCU’s maximum output voltage
Development Environments Language: C Testing: DevC++ V 4.9.9.2 Implementation: Code Composer Studio V4.2.1.00004 Wireless: SimpliciTI Schematics: Cadsoft EAGLE V 5.11.0
Development Kit MSP-FET430UIF EM430F6137RF900
Fall Detection Algorithm Accurate, Fast Fall Detection Using Gyroscopes and Accelerometer-Derived Posture Information
Fall Detection - Acceleration Sample Output • The linear acceleration and rotational rate of the chest and thigh for: • Standing • Walking • Sitting • Running
Wireless Cc1101: 4mm x 4mm CC1101 Evaluation Module 433MHz Example SimpliciTIStructure
Remaining Tasks • Finish and order PCB design • Transferring code on boards • Bluetooth interfacing • Coding for the oximeter • Interfacing system clocks • Lots and lots of testing!
Budget Original budget Current spending