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ICL-GNSSTampere, Finland June 29-30, 2011
CWINS
RF Localization Inside Human BodyEnabling micro-robotic navigation for medical applications
K. Pahlavan, Y. Ye, U. Khan and R. Fu
June 29, 2011 ©KP
Overview of CWINS Program on BAN Current Project: RF Propagation Measurement and Modeling for
Wireless Body Area Networks – Sponsored by NIST Staff and Students at the CWINS Lab:
– Kaveh Pahlavan– Allan H. Levesque (research scientist) – Kaveh Ghaboosi (Post Doc)– Reza Zekavat (visiting professor)– Ning Yang (affiliated research scientist)– Yunxing Ye, Fardad Askarzadeh (PhD)– Umair Khan, Ruijun Fu, Shen Li, Pranay Swary (MS)– Monir Islam (UG)
Staff and Student at the Antenna Lab:– Sergey Makarov– Gregory M. Noetscher, Yang Xu (MS)– Ishrak Khair (UG)
“the most profound technologies are those that disappear…they weave themselves into the fabric of everyday life until they are indistinguishable from it”
Mark Weiser
Enabling technologies were wireless access and localization.
Innovations starts with science fictions and technical challenges!
Source for images: google images
A new realm: BAN
How can we localize the capsule using RF signal? Source for images: google images
Who needs this technology? Immediate application is Capsule Endoscopy that is a way to record
images of the digestive tract for use in medicine. The capsule is the size and shape of a pill and contains a tiny camera. After a patient swallows the capsule, it takes pictures of the inside of the gastrointestinal tract. The primary use of capsule endoscopy is to examine areas of the small intestine that cannot be seen by other types of endoscopy procedures. This type of examination is often done to find sources of bleeding or abdominal pain. The procedure was approved by the U.S. Food and Drug Administration (FDA) in 2001 (source: Wikipedia).
It is desirable for diagnostics and Gastrointestinal Surgery to associate the photos to the location and orientation of the capsule [1].
Long term vision is for navigation of micro-robots for percision drug delivery and surgical missions.
June 29, 2011
David Cave, “Wireless Video Capsule Endoscopy”, 1st Invitational Workshop on BAN Technology and Applications, WPI, June 20, 2011.
What is the technical challenge?
Since measurements inside human body is very difficult we need a simulation environment for performance evaluation of alternative technologies.
Performance evaluation needs channel models
[1] M. Heidari and K. Pahlavan, Performance Evaluation of Indoor Geolocation Systems Using PROPSim Hardware and Ray Tracing Software, IWWAN, Oulu, Finland, June, 2004[2] M.A. Assad, M. Heidari, and K. Pahlavan, "On RSS and TOA based Indoor Geolocation - A Comparative Performance Evaluation," IEEE Global Communications Conference, November 2007.
Implant device
Body mounted device
Body base station
External access point
Internet
Channel for in-body localizationImplant to implant
Implant to surfaceImplant to externalSurface to surface LOSSurface to surface NLOSSurface to external LOSSurface to external NLOS
Channel Models for- RSS-based systems [A]- TOA-based systems [NA]
June 29, 2011
Frequency bands for in-body localization
11
RSS localization and NB characteristics
Average received power
Shadow fading
Multipath fading
Distance in logarithmic scale
Path-loss model for inside human body
Implant to Body Surface Lp(d0) α σdB
Deep Tissue 47.14 4.26 7.85Near Surface 49.81 4.22 6.81
0 0 0( ) ( ) 10 log( / ) ( )p pL d L d d d S d d
Kamran Sayrafian-Pour,,Wen-Bin Yang, J. Hagedorn, J. Terrill, J. ; Kamya Yazdandoost, "A statistical path loss model for medical implant communication channels," Personal, Indoor and Mobile Radio Communications, 2009 IEEE 20th International Symposium on , vol., no., pp.2995-2999, 13-16 Sept. 2009.
NIST/IEEE 802.15.6 Model using HFSS software simulation:
A scenario for performance analysis
June 29, 2011
Yi Wang, Ruijun Fu, Yunxing Ye, Umair Khan, and Kaveh Pahlavan, “Performance Bounds for RF Positioning of Endoscopy Camera Capsules”, Proceedings of the IEEE Topical Conference on Wireless Sensors and Sensor Networks, Phoenix, AZ, 16-20 January 2011.
Performance for capsule endoscopy
0 10 20 30 40 50 60 703
4
5
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Number of receiver sensors on body surface
90 p
erce
ntile
loca
lizat
ion
RM
SE
(mm
)
Localization performance as a functionof number of receiver sensors in different organs
stomachsmall intestinelarge intestine
1 2 3 4 5 6 7 8 9 1030
32
34
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40
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50
Number of Pills
90 p
erce
ntile
RM
SE
(mm
)
Localization performance as a function of numb of pills in each organ
StomachSmall intestineLarge Intestine
Yunxing Ye, Umair Khan, Ruijun Fu and Kaveh Pahlavan. “On the accuracy of RF positioning in multi-capsule endoscopy” 22nd Annual IEEE international symposium on personal, indoor and mobile radio communications PIMRC 2011, 11-14 Septembre, Toronto, Canada.
4/27/2009
The first path is not detectable by measurement system - Undetected Direct Path (UDP) [1]
Measurement bandwidth is not wide enough to distinguish the first few paths from each other [2]
Limitations on Bandwidth Undetected Direct Path
Challenges for TOA indoor geolocation
[1] K. Pahlavan, P. Krishnamurthy and J. Beneat, “Wideband Radio Propagation Modeling for Indoor Geolocation Applications”, IEEE Communications Magazine, April 1998.[2] B. Alavi and K. Pahlavan, “Bandwidth Effect on Distance Error Modeling for Indoor Geolocation,” 14th Annual IEEE International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC’03), Beijing, China, September 7-10, 2003.
Other challenges for in-body localization
How body affects multipath?
What is the effect of non-homogeneousity of human body on TOA ranging?
What are the effects of body motions?
How can we measure inside human body?
June 29, 2011
WB measurement on body-surface
S. J. Howard and K. Pahlavan, "Measurement and Analysis of the Indoor Radio Channel in the Frequency Domain", IEEE Trans. on Instrumentation and Measurements, Oct. 1990.
June 29, 2011
In BAN applications rooms are smaller
Paths are closer, may be we need wider bandwidth ?
June 29, 2011
Path-loss through body is high
May be we need to do our measurements in a chamber with absorbing material?
Effects of non-homogeneousity1 2
1 2 1
1 1 2
ˆ ˆ ˆ ˆ ˆ( ... )
( ... )/ / /
nr
ni
i i n
cd v
d d d dc cv c c c
-150 -100 -50 0 50 100 150-200
-150
-100
-50
0
50
100
150
200illustration of the calculation scenario (a cross section of human torso)
large intestinesmall intestinestomachright kidneyleft kidneygallbladderliver
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35-0.5
0
0.5
1
1.5
2
2.5
Distance (m)
C*
500 random point experiment
datalinear fit
=52.95std(dme)=6.03mm
Yunxing Ye, Umair Khan and Kaveh Pahlavan “Performance bounds for TOA based RF positioning for implant communication” 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC '11), Boston. August 30th – September 3rd 2011.
Measurement of body permittivity
June 29, 20110 100 200 300 400 500 600
0
20
40
60
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100
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TOA (ns)
Dis
tanc
e be
twee
n th
e Tx
and
Rx
(cm
)
Linear fitting to get the average permitivity of human body tissue
Measured data Lie fitting results
r()=1.40
r
cv
Effects of human movements
June 29, 2011
Umair I. Khan, Kaveh Pahlavan, Sergey Makarov “Comparison of TOA and RSS Based Techniques for RF Localization inside Human Tissue”, 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC '11), Boston. August 30th – September 3rd 2011.
Controlled body-surface measurement inside interference shielded chamber
June 29, 2011
June 29, 2011
Effects of body movements
Speed of human motions
•(a) No motion •(b) Stand Still
•(c) Walk •(d) Jog
[1] S. Howard and K. Pahlavan, "Doppler Spread Measurements of the Indoor Radio Channel", IEE Elec. let, Jan. 19, 1990.[2] Ruijun Fu, Yunxing Ye, Kaveh Pahlavan and Ning Yang , "Doppler Spread Analysis of Human Motions for Body Area Network Applications" 22nd Annual IEEEinternational symposium on personal, indoor and mobile radio communications PIMRC 2011, 11-14 September , Toronto, Canada.
In-body measurements, hollow Phantom and absorbing chamber
Phantoms Phil with bones and organs
June 29, 2011
[1] “Full body custom liquid-Phil manual,” the phantom laboratory Inc, Salem, NY.[2] Jones, D.N.; Lebsack, E.T.; Teig, L.J.; Wilder, W.C.; , "A comparison of antenna patterns measured on a person, on a phantom, and computed, for backpack-mounted antennas worn by a person," MILCOM 2002. Proceedings , vol.1, no., pp. 642- 646 vol.1, 7-10 Oct. 2002
Sample in-body measurements for TOA localization
June 29, 2011
0 5 10 15 20 25 30 35 40 45 50-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
delay(ns)
Pow
er(d
B)
free space experiment (antenna opposite dirction,2.0GHz~2.4GHz)
air to outsideinside water to outside
0 5 10 15 20 25 30 35 40 45 50-110
-100
-90
-80
-70
-60
-50
-40
-30
delay(ns)
Pow
er(d
B)
free space experiment (antenna same dirction,2.0GHz~2.4GHz)
air to outsideinside water to outside
0 5 10 15 20 25 30 35 40 45 50-110
-100
-90
-80
-70
-60
-50
-40
-30
delay(ns)
Pow
er(d
B)
Chamber experiment (antenna opposite dirction,2.0GHz~2.4GHz)
air to outsideinside water to outside
0 5 10 15 20 25 30 35 40 45 50-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
delay(ns)
Pow
er(d
B)
Chamber experiment (antenna same dirction,2.0GHz~2.4GHz)
air to outsideinside water to outside
In-body simulation with calibrated measurement
June 29, 2011
F. Askarzadeh, Y. Ye, U. Khan, F. Akgul, K. Pahlavan and S. Makarov, “Computational Methods for Localization in Close Proximity ”, chapter of Position Location - Theory, Practice and Advances: A Handbook for Engineers and Academics, John Wiley and Sons, 2011.
Ansoft HFSSTM vs Measurements
Fast FDTD simulation using Matlab
June 29, 2011
Sergey N. Makarov, Umair I. Khan, Md. Monirul Islam, Reinhold Ludwig, Kaveh Pahlavan “On Accuracy of Simple FDTD Models for the Simulation of Human Body Path Loss”, presented at the 2011 IEEE Sensor Application Symposium, San Antonio, TX, February 22-24, 2011
Challenges in computer simulations
-1 0 1 2 3 4 50
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Umair I. Khan, Kaveh Pahlavan, Sergey Makarov “Comparison of TOA and RSS Based Techniques for RF Localization inside Human Tissue”, 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC '11), Boston. August 30th – September 3rd 2011.
Summary and conclusions
Localization inside human body is an interesting emerging area of research because it– Enables a number of emerging applications such as capsule
endoscopy and micro-robot surgery– There are a number of fundamental issues for research in this field
We addressed some of these challenges and presented some of our preliminary research results on– Effects of non-homogenous human body on TOA ranging– Measurement of body motions for different human activities– Alternative techniques for range measurement inside human body
More recent video and power point presentations on the general area is available at http://www.cwins.wpi.edu/workshop11
June 29, 2011
