V i t a l i s
ECE 477 - Spring 2013TEAM 13
Presenter: Yi Shen
Wireless Biometric Sensor
Team Members: Aakash Lamba
Di MoShantanu Joshi
Yi Shen
Reliability and Safety Analysis
• Prototype of a portable wireless biometric
sensor
• Battery-powered device with fuel gauge
• Mounted on the wrist
• Monitor vital signs such as pulse rate, SpO2
and skin temperature
• Transmit the information via Wi-Fi for
remote web access
• NFC chip allows immediate access
• Accelerometer on the shoulder for fall
detection
• Manual and automatic alarm system.
Project Overview
High Criticality
Involves injury to the user
Causes system not operable
Failure rate of or less is acceptable
Medium Criticality
Does not present direct harm to the user
Renders system unusable
Failure rate of or less is acceptable
Low Criticality
Potential harm to the user / Causes inconvenience to user
Failure rate of or less is acceptable
Definition of Criticality Levels
1.Microcontroller: Atmel – ATmega 1284
2.Light-To-Frequency Converters: TAOS –
TSL230RD
3.Charger/Booster: Charger – MC73831
Boost Converter –
TPS61200
Components Failure Analysis
Microcontroller: Atmel –
ATmega 1284MOS digital microprocessor devices (Mil-Hdbk-217F)
1 2( )p T E Q LC C
Parameter
Description Value Comment
Die complexity failure rate
0.14 8-bit microcontroller
Temperature factor 0.98 Operating at 85 °C
Package failure rate 0.021 44-pin SMT
Environment factor 4.0 Ground Mobile
Quality factor 10 Other Commercial Level
Learning factor 1 > 2 yrs in production
Reliability 2.212 [Failures/
MTTF Entire Design 51.607 years
1C
T
2C
L
p
QE
Light-To-Frequency
Converters:
TAOS – TSL230RDLinear Gate / Logic Array (Mil-Hdbk-217F)
1 2( )p T E Q LC C
Parameter
Description Value Comment
Die complexity failure rate
0.01 <100 transistors
Temperature factor 7.0 Operating at 30 °C
Package failure rate 0.0034 8-pin SMT
Environment factor 4.0 Ground Mobile
Quality factor 10 Other Commercial Level
Learning factor 1 > 2 yrs in production
Reliability 0.836 [Failures/
MTTF Entire Design 8.36 136.55 years
1C
T
2C
L
p
QE
Charger – MC73831Linear Gate / Logic Array (Mil-Hdbk-217F)
1 2( )p T E Q LC C
Parameter
Description Value Comment
Die complexity failure rate
0.01 <100 transistors
Temperature factor 7.0 Operating at 85 °C
Package failure rate 0.0020 5-pin SMT
Environment factor 4.0 Ground Mobile
Quality factor 10 Other Commercial Level
Learning factor 1 > 2 yrs in production
Reliability 0.78 [Failures/
MTTF Entire Design 146.35 years
1C
T
2C
L
p
QE
Boost Converter –
TPS61200Linear Gate / Logic Array (Mil-Hdbk-217F)
1 2( )p T E Q LC C
Parameter
Description Value Comment
Die complexity failure rate
0.01 <100 transistors
Temperature factor 7.0 Operating at 85 °C
Package failure rate 0.0043 10-pin QFN
Environment factor 4.0 Ground Mobile
Quality factor 10 Other Commercial Level
Learning factor 1 > 2 yrs in production
Reliability 0.870 [Failures/
MTTF Entire Design 8.72 130.91 years
1C
T
2C
L
p
QE
Schematic: Section Breakdown
Microcontroller
Power and Battery Management
Sensors
External Interfaces
FMECA Chart
Microcontroller: Atmel –
ATmega 1284Failure
No.
Failure Mode
Possible Causes
Failure Effects
Detection Method
Criticality
A1 Failure of UART
Wrong connections for
TX/RX
Wi-Fi and OLED won’t
communicate with micro properly
Inspection High
A2 Over-current Decoupling Capacitors are
shorted
Micro doesn’t function any
more
Inspection and ICD3 debugger
High
A3 Failure of I2C Pull-up resistors are
shorted
Unable to retrieve data
from temp sensor and fuel gauge
Inspection Medium
A4 Failure of GPIO
Bad wire connections
Unable to detect falling
position/ control LEDs
for SpO2 Sensors
Inspection Medium
Failure
No.
Failure Mode
Possible Causes
Failure Effects
Detection Method
Criticality
B1 Failure to operate
Bad solder for GND and Vcc
Micro won’t receive any data about
patient pulse and blood
oxygen concentration information
Inspection Medium
FMECA Chart
Light-To-Frequency
Converters:
TAOS – TSL230RD
Failure
No.
Failure Mode
Possible Causes
Failure Effects
Detection Method
Criticality
C1 Overheat Too much current
Damage Battery
Inspection high
FMECA Chart
Charger – MC73831
Failure
No.
Failure Mode
Possible Causes
Failure Effects
Detection Method
Criticality
D1 Over-heat Too much current
Output less than 5V, OLED screen won’t be powered
on
Observation Medium
FMECA Chart
Boost Converter – TPS61200