wireless body sensor network opportunities and...

ASTRI Proprietary

Wireless Body Sensor Network – Opportunities and Challenges

Andy Wu

Principal Engineer IC Design, ASTRI

Portable Analog Mixed Signal Design

Nov 08, 2013

ASTRI Proprietary

Outline

• Wireless Body Sensor Network Overview

• Background

• WBSN Market Opportunities

• Sensor Node Architecture & Requirements

• Sample WBSN application

• Challenges of WBSN

• Future Development opportunities

• Conclusion

2

ASTRI Proprietary

Wireless Sensor Network Overview

What is Sensor Network?

• Clusters of communicating sensor nodes which collect and process

information

• Share information with neighboring or surrounding nodes or nearby data

collection stations.

Smart Building Transportation & Logistics

Industrial & Factory

Automation

Environmental Monitoring Healthcare

Security & Surveillance 3

ASTRI Proprietary

WBSN consists of multiple interconnected nodes, on, near, or within

a human body to provide sensing, processing and communication

capabilities.

Wireless Body Sensor Network

4

ASTRI Proprietary

Outline


• Background






• Conclusion

5

ASTRI Proprietary

• Moore’s Law is making sufficient

CPU performance available with

decreasing size and total power.

Why Wireless Body Sensors now?

• Advances in Materials Science

has resulted in novel sensing

materials for many Chemical,

Biological, and Physical sensing.

•Wireless Transceivers

are becoming smaller,

less expensive, and less

power hungry.

• Power supply improvements in

batteries and energy scavenging, are

expanding application options.

6

ASTRI Proprietary

Applications Enabled By WBSN

Vital Signs Monitoring (EMG, ECG, SPO2, Blood Pressure,

Glucose level, etc.)

Fitness & Gaming (Calorie Burnt, Heart Rate Monitor, Sleep

analysis, etc.)

Electronic Drug Delivery (Swallowable pill, Implanted

device, etc.) WBSN

7

ASTRI Proprietary

Outline


• Background






• Conclusion

8

ASTRI Proprietary

Wearable Technology Market

Wearable Technology Market

has potential to grow to 171

million units and exceed $6

billion by 2016

Source – IHS IMS Research

9

ASTRI Proprietary

10

Wireless Body Sensor Market

ONworld projects 515M units

In 2017.

Chip set ASP = $3

World wide market potential

@ US$1.5B by 2017 for

WBSN IC

“Advances in low power wireless communications, MEMS and multi-

sensor arrays have resulted in viable body area network applications for

clinical patient monitoring, assisted care, at-home chronic disease

management and general wellness,” says Mareca Hatler, ON World’s

research director.

10

ASTRI Proprietary

Outline


• Background






• Conclusion

11

ASTRI Proprietary

Typical WBSN Architecture

Master Node

• Portable device for central control, processing and interface

to the user

Slave Node

• Sensor nodes for biomedical information acquisition, signal

processing, wireless transmission.

Master Node

Slave Node Internet / LTE …

• ECG

• EMG

• Heart Rate

• SPO2

• Glucose

• Temperature

12

ASTRI Proprietary

Wireless Body Sensor Node

Sensor Node Architecture:

• Sensing module

• ADC / Analog Front End

• Microprocessor

• Power supply

• Communication Unit

Sensors

Power supply

ADC

MCU

An

tenn

a

Tx

Rx

13

ASTRI Proprietary

WBSN Sensors Requirement

Physiological Parameter Specifications

Electrocardiogram (ECG) Frequency: 0.3Hz – 100Hz

Amplitude: 0.25 – 1mV

Electromyogram (EMG) Frequency: 10Hz – 500Hz

Amplitude: 50uV – 6mV

Electroencephalogram (EEG) Frequency: 0.5Hz – 100Hz

Amplitude: 1uV – 100uV

Blood Pressure (BP) Systolic: 60-200mmHg

Diastolic: 50-110mmHg

Body Temperature 320C – 400C

Galvanic Skin Response (GSR) 0 – 100KW

Saturation of peripheral oxygen

(SPO2)

80-100%

Heart Rate (HR) 40-220 Beats per minute

Respiratory Rate (RR) 2-50 breaths per minute

Frequency 0.1 – 10Hz

Sensor

specifications

Physiological Sensors -> ECG/EMG/EEG/BP/SpO2/temperature monitoring

Biokinetic Sensors -> Acceleration and angular rate of rotation

Ambient Sensor -> Humidity, light, temperature

14

ASTRI Proprietary

Sensor How it works Data rate

ECG/EEG/EMG Measures the potential difference across

electrodes placed on different parts of the body

High

Pulse Oximetry Measures the absorbance of the red and

infrared light passing from one side to the other

side of a selected body’s anatomy (e.g. finger)

Low

Blood Pressure Measures the systolic and diastolic pressure

Low

Blood Glucose Measure the total charge passing through the

electrode proportional to the amount of glucose

in the blood.

Low

Accelerometer Measures the acceleration relative to freefall in

three axes

High

Gyroscope Measures the orientation based on the

principles of angular momentum.

High

Temperature Detect the temperature changes by measuring

the resistance changes of a silicon integrated

circuit

Very low

Typical WBSN Sensors

15

ASTRI Proprietary

WBSN Sensors Requirement

Sensitivity & Calibration

• Sensitivity and electrical performance of body-worn sensor can be

affected due to changes in environmental conditions and may require

recalibration

Placement specific

• Unintended placement can significantly degrade the data’s quality

Noise Reduction

• Signal processing required to handle motion artifacts, placement errors

and coupling from other noise sources

Low signal frequency & amplitude

• Relatively low sampling frequency and low data rate for signal

transmission

16

ASTRI Proprietary

WBSN Data Rate Requirement

Electrocardiogram (ECG)

• 72 kb/s

(500 Hz sample, 12-bit ADC, 12

channels)

Electromyogram (EMG)

• 768 kb/s

(4 kHz sample, 16-bit

ADC, 12 channels)

Electroencephalogram (EEG)

• 115.2 kb/s

(300Hz sample, 16-bit ADC, 24 channels)

Blood Pressure (BP)

• <10 kb/s

Body Temperature

• <10 kb/s

Pulse Oximetry (SPO2)

• 16 kb/s

(500Hz sample, 16-bit ADC, 2 channels)

17

ASTRI Proprietary

Comparison for Different Wireless Options

Standard BLE Zigbee ANT+ UWB WiFi

Peak Current 12-16mA 30-40mA 17mA 227mA 116mA

Frequency

Band

2.4GHz 2.4GHz 2.4GHz 3.1~10.6

GHz

2.4GHz;

5GHz

Data/Chip rate 1-Mbps 2-Mbps 1-Mbps 110Mbps 54-Mbps

Range 50m 100-300m 10m 10m 150m

Latency 2.5ms 20ms,

30ms from

sleep

~zero ~zero 1.5ms

Network

Topology

Star Mesh Mesh Peer-to-

Peer

Star

Interference

Immunity

Good Good Worse Good Good

Suitability for

WBSN

18

ASTRI Proprietary

WBSN Communication Unit Requirement

Reliable Data Transfer

• Low transmission power and small sized antenna can reduces signal to

noise ratios yet reliable data transfer is crucial

Compatibility and Interference

• Multiple sensory devices might interfere with each other, especially in the

unlicensed industrial, scientific and medical band

Robust against transmitted signals attenuation

• Signal attenuation from body shadowing, line of sight absorption of RF

signal

QOS & Security

• Vital sign data should be guaranteed to delivered within reasonable delay

• Encrypted data transmission to ensure confidentiality and privacy

19

ASTRI Proprietary

WBSN Signal Processing Platform

• Signal Processing

• Amplify weak signals

detected from sensors

• Filter noise injected from

other sources

• Extract signal of interest

with sufficient resolution

• Identify specific events as

a trigger for notification

• Store or transmit the

processed data based on

applications

20

ASTRI Proprietary

• Low noise, high gain analog front end to process the acquired signal

• High resolution low power analog to digital converter

• Low power microcontroller to process the data for storage or transmission


Sensor

Signals

Bluetooth RFIC options

RF in/out Digital

in/out

Power Management IP..

Inst

Amp

IN

SEL

A

IN

SEL

B SW CAP

Filter

VREF

Multi-

channel

12 Bit

ADC

Setup

REG

Data

REG .

.

21

ASTRI Proprietary

22

SpO2 Oxygen Saturation Percentage In Blood

Oxygen saturation percentage in blood can be

measured by placing finger between a dual light

(read and infrared) source and a photodetector, the

photodetector records the relative amount of each

color absorbed by arterial blood and transmitted

the data for calculation.

SpO2 signal specification:

Dark current: 5nA

Photodiode current: 0.05mA~37mA

LED Driver

Voltage Reference LED

Current Control

12bit DAC

14bit ADC

AFE

SPI I2C

PGA

Sensor

Input

RED

Amb(RED)

IR

Amb(IR)

TIA

OSC

PWM

22

ASTRI Proprietary

23

ECG Electrocardiogram

The ECG works mostly by detecting and amplifying

the tiny electrical changes on the skin that are

caused when the heart muscle "depolarises"

during each heart beat.

ECG signal specification:

Frequency range: 0.5Hz ~ 100Hz

Amplitude: 0.25mV ~ 1mV

23

ASTRI Proprietary

WBSN Signal Processing Unit Requirement

Low noise, high precision Analog Front End

• Instrumentation amplifier, high resolution ADC for signal

acquisition

Ultra low power microcontroller

• Minimization of both peak & average power consumption

• Deep sleep mode to shutdown the circuit when idle

• Dynamic voltage / frequency scaling to preserve power

Configurable Analog / Digital Circuit

• Programmable amplifier, configurable DAC/ADC to

interface with sensors

• Algorithm for noise reduction and signal processing in

digital domain

24

ASTRI Proprietary

Outline


• Background



• ASTRI’s Solution for WBSN



• Conclusion

25

ASTRI Proprietary


Key Features

• Chopper Stabilized Instrumentation Amplifier with Input Referred Noise <1uVrms (0.5Hz – 150Hz)

• Proprietary Switched Capacitor Programmable Gain Amplifier

• ARM Cortex-M0

• 12bit 200ksps/14bit 1Msps SAR ADC

• 12bit 20ksps Sigma Delta DAC

• TSMC 0.18um/SMIC 0.13um technologies

• ECG demos available

ASTRI’s BSN SOC Architecture TSMC 0.18um SOC Die Photo SMIC 0.13um SOC Die Photo

ASTRI’s ECG Demo

26

ASTRI Proprietary

WBSN ECG Demo …

ASTRI Proprietary

BLE Digital Baseband and RF

SEU’s

Design

GFSK Modem, Packet Synchronization, Whitening, CRC, AES

Encryption

ASTRI’s

Design

RF Controller with Channel Selection, FSM, interfaces to MCU,

Packet Processing

Electrical Specifications

Frequency Band: 2.400GHz ~ 2.4835GHz

No. of Channels: 40

Channel Width: 2MHz

Tx Power: -20dBm ~ 10dBm

Rx Sensitivity: -85dBm

Modulation: GFSK

Modulation Index: 0.45 ~ 0.55

Data Rate: 1Mbps

Robustness: Adaptive Frequency Hopping

Encryption: 128bit - AES

Packet Length: 80bit ~ 376bit

28

ASTRI Proprietary

Conventional RF Transceiver

ASTRI’s Re-configurable Digital RF

Re-configurable Digital RF

Conventional RF Transceiver ASTRI’s Re-configurable Digital RF Transceiver Key Specification

Cartesian Transmitter with RF Mixers &

Quadrature LO Power Hungry

Direct Digital Phase Conversion with Polar

Transmitter Low Power

TX Power: 16.6mW

Linear Power Amplifier Power Hungry Digital Amplitude Modulated non-linear Power

Amplifier Low Power

PA Power: 4mW

PA Efficiency:18%

Analog Controlled PLL Power Hungry

Fixed Frequency

All Digital Fractional-N PLL Low Power

Tunable from 2.4-2.4835GHz

PLL Power : 5.7mW

Frequency:

2.4GHz(BLE)

Fixed A/D,D/A, LPF & digital

modulation/demodulation Fixed Modulation

Scheme & Data Rate

Reconfigurable A/D, D/A, LPF & digital

modulation/demodulation Adaptive Modulation

Scheme & Data Rate

Data Rate: 1Msps(BLE)

Modulation Scheme:

GFSK

Hard to scale and integrate in nanometer process

Easy to port and integrate in lower geometry

65nm Process

ASTRI Proprietary

S1

EXT

Sensors

S2

S3

SAW

Wireless Body Sensor Signal Processing Platform

(ART 133)

RF Transceiver

TX

RX

Ultra Low Power RF IPs & SOC Platform for WBSN

Digital

Baseband

FPGA

Complete set of IPs for Wireless Body Sensor Network

30

ASTRI Proprietary

Outline


• Background






• Conclusion

31

ASTRI Proprietary

Challenges of WBSN

Energy-efficient

• Power minimization technique for the sensor, controller and RF transmitter

• High energy density battery technology

• Power Scavenging methods

Increasing sensor integration

• Detection of human’s motion, temperature, heart rate and blood pressure simultaneously

Sensitivity and Accuracy

• Sensor and signal processing chain must truthfully capture the biological signals

32

ASTRI Proprietary

Challenges of WBSN

Higher processing performance

• Sophisticated signal processing algorithm and complex application may require higher computational performance

Robustness and Security

• Reliable operation of WBSN

• Secure transmission of data to ensure privacy

Value and Ease of use

• Perceived value must be higher than the price paid

• Small, unobtrusive, ergonomic, easy and intuitive to use

Safety and Biocompatibility

• Compliance to regulatory requirements

• No Harmful effects of long term continuous use

33

ASTRI Proprietary

Outline


• Background






• Conclusion

34

ASTRI Proprietary

Future Development Opportunities

Physical characteristics of sensor materials and electronic circuits

• Flexible electronics

• Biocompatibility

Power Source issues • Remote battery charging

• Energy harvesting

Security, authentication and privacy issues

Ultra-low power signal processing

and RF transceiver

Network resource management

35

ASTRI Proprietary

Outline


• Background






• Conclusion

36

ASTRI Proprietary

Conclusion

Wireless Body Sensor Network presents a billion dollar market of consumer applications

Sensor Node must be unobtrusive, easy to put on while operating at extremely low power, with reliable, secure wireless data transmission

Pretty of open research area in materials, packaging, energy supply, signal processing and wireless networking

Design trade off between energy consumption, processing, communication resources and the fidelity, throughput in the smallest possible package

Wireless Body Sensor Network could be the next life saving technology you need!

37

ASTRI Proprietary

End of Presentation Thank you. Questions are welcome.

Andy Wu [email protected]

Our corporate website: www.astri.org

wireless body sensor network opportunities and...

Documents