Components and Network Architecture for Galvanic Coupled Cyber Physical Body Network

[1] ICNIRP (International Commission on Non-Ionizing Radiation Protection). 1998. Guidelines for limiting exposure to time-varying electric, magnetic, & electromagnetic fields (up to 300 GHz).

[2] M Swaminathan, FS Cabrera, G Schirner, and K R Chowdhury, Characterization and Signal Propagation Studies for Wireless Galvanic Coupled Body Sensors, IEEE Journal on Selected Areas in Communications, under review.

[1] ICNIRP (International Commission on Non-Ionizing Radiation Protection). 1998. Guidelines for limiting exposure to time-varying electric, magnetic, & electromagnetic fields (up to 300 GHz).

[2] M Swaminathan, FS Cabrera, G Schirner, and K R Chowdhury, Characterization and Signal Propagation Studies for Wireless Galvanic Coupled Body Sensors, IEEE Journal on Selected Areas in Communications, under review.

Electrical and Computer Engineering Department, Northeastern University, Boston, MA 02115 USA.

References

Protocol Design at Network Layer

Channel gain for on skin GC-links

We constructed a 2-port equivalent circuit model & FEM based ANSYS HFSS simulation suite of human arm using electrical properties of tissues [1].

obtained an estimate for observed noise and achievable data rates

identified optimal transmission frequency and electrode placements

under varying tissue dimensions

skin to muscle & intra-muscle links showed lower loss than on-skin links

The spatio-temporal distribution should be analyzed and leveraged for multiple channel access Eg. TDMA

The network should distinguish critical situations from normal deviations based on correlations derived from routine activities Eg. High heart rate from heavy activity vs emergency

Building transmitter and receiver circuits with suitable modulation schemes that maximizes transfer rate

Studying the impact of realistic noise figures on capacity

Optimizing Node

Placement

Outcome:• Fewer Relays• Energy saving• Higher data-rate

Guiding signal

through body

Establishing path from node to

controller

Objective: Establishing reliable & energy efficient CP-BN physical layer

The Promise of Implanted Sensors

Signal Propagation Through Human Tissue – Our Models

CP-BN operation and performance needs to be Evaluated by building test-beds using

Human phantoms Animal experiments Clinical trials

CP-BN Test-bed

Future health-care relies on autonomous sensing of physiological signals and controlled drug delivery

Need for implanted Cyber – Physical Body Sensor Network (CP-BN) that can wirelessly communicate with an external control point

Channel Capacity

Physical Protocol

Topology

Meenupriya Swaminathan & Kaushik R. Chowdhury{meenu, krc} @ece.neu.edu

Implementation of Physical Layer

Why Galvanic Coupled CP-BN

Galvanic Coupling on Skin (a) Front View (b) Cross Section

Injects low power electrical signal to the tissues Weak secondary currents carry data to receiver Signal propagates radially across multiple tissues & suffer losses

How Galvanic Coupling Works

Gal

van

ic C

ou

pli

ng

RF

10-6

10

-5

10-4

10-3 (

J)

Lower health care cost

Remote diagnosis & care

Proactive care & increased longevity

Synchronization

Link Quality Analysis

…CP-BN

Self Adaptation

Future Research Challenges

Support: U.S. National Science Foundation (Grant No. CNS-1136027). Thanks to our collaborators Gunar Schirner, Northeastern University and Ferran Cabrera, Universitat Polit`ecnica de Catalunya, Barcelona, Spain.

Acknowledgement

Galvanic Coupled Cyber-Physical Body Sensor Network

Coupler

Ground Sig

nal

Pro

cess

ing

Impl

ant

Coupler

GroundSig

nal

Pro

cess

ing

Sen

sor

Coupler

GroundSig

nal

Pro

cess

ing

Coupler

GroundSig

nal

Pro

cess

ing

Mem

ory

Mem

ory

RF

T

rans

ceiv

er

Coupler

Ground Sig

nal

Pro

cess

ing

Impl

ant

Access Point

Controller

Relays

Sensor/Actuator

Intra-body Network

Extra-body Network

Data Transfer

Data Aggregation

Data Retrieval

Human Body

Implanted node

On Surface node

Relay

Controller

GC Link

GC Link

RF Link

Access Point

Relay to Controller GC Link

Node to Relay GC Link

RF Link

Node A

Node B

Node C

Controller

Traffic to/from node ATraffic to/from node B

Traffic to/from node C

Data Aggregation

Data Retrieval

Cha

nnel

Mod

el G

C

Link

, Top

olog

y,

Mod

ulat

ion S

tora

ge &

Fau

lt D

etec

tion

Rat

e A

dapt

atio

n,S

calin

g

Data TransferR

F L

ink

CS

MA

&

BE

S

Mul

tiple

xing

, S

ynch

roni

zatio

n C

hann

el A

cces

s &

To

polo

gy c

ontr

ol

Que

uing

Relay

Skin Fat Muscle

Existing RF based BNs not suitable for human tissues containing water consume more power does not propagate inside body tissues

Galvanic coupled CP-BN mimics body’s natural signalling (low frequency signals) low interference as energy is confined within body consumes two orders of magnitude less energy