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

Block Diagram

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

Questions?