Medical sensing, localization, and communications using ultra wideband technology

(MELODY)

Ilangko Balasingham

Project Leader

http://www.melody-project.info

Project info

• Consortium core – Oslo universitetssykehus HF – NTNU – Forsvarets forskningsinstitutt – University of Oslo (2008-2012)

• Industry panel

– Given Imaging, USA – OmniVision, Norway

– Novelda (2008-2012) – IBM (2008-2012) – ABB (2008-2012) – Atmel (2008-2012) – Hospitality (2008-2012)

• International expert panel

– National Institute of Information and Communication Technology, Japan

– Nagoya Institute of Technology, Japan – Technical University of Dresden, Germany – GE Healthcare, UK – SORIN Group, France

NFR: StorIKT/VERDIKT program 01.09.2008 – 31.12.2015 : - Total budget: 48 M.kr. (NFR: 36 M.kr.) - 8 PhD and 17 Postdoc man-years

Results (2008-2012) • 24 journals (4 in level 2) • 1 book chapter • 72 peer-reviewed full conference papers (level 1) • 6 abstracts with poster/oral presentations • 7 popular articles in Norwegian and international media • 2 patents filed, 3 DOFIs submitted

• 4 master theses • 4 PhD defended - 2 PhD theses submitted • 12 Postdoc projects completed

• Int. visitors: 2 prof’s, 2 PhDs, 4 master students • 4 of our PhD students spent 3-12 months abroad

• Organized special sessions in 4 international conferences and annual

workshops with international talks given by international experts

Some of the future challenges

• Increased cost due to readmissions and follow up treatment and care of chronic sick patients (diabetes, cardio vascular, cancer, etc.) to hospitals (“svingdør-pasienter)

• Improved personalized healthcare (long term monitoring and customized treatment on an individual basis) in ubiquitous manner

Wireless health technology?

Problem • Can wireless technology be used

– to measure vital signs (heart rate, respiration, blood pressure) continuously and remotely without any contact?

– to do high resolution, cost effective imaging without any contact with non ionizing radiation?

– to localize and track objects inside the human body without imaging?

– to transmit high data rate sensor signals from devices implanted deep inside the human body at receivers located outside in a robust, reliable manner?

MELODY Overview

Ultra wideband (UWB) technology (3.1 – 10.6 GHz)

• Characteristics – ultra-short pulses, low duty cycle, fine time resolutions – Imaging,

sensing, localization, tracking

– very large bandwidth, extremely low power spectral density, excellent propagation, low interference generation and good interference rejection, coexistence with conventional systems, almost undetectable – wireless communication

– Possibility to address all three application domains such as communications, localization and sensing within one single technology

Ultra Wide Band (UWB)

• Regulations – 3.1-10.6 GHz

– EIRP<-41.3 dBm

– Max <0.5 mW

• Bandwidth – > 500 MHz or

– 20% of center frequency

Largest unlicensed bandwidth ever released!

MELODY Research Fields (2008-2012-2015)

UWB Technology

Sensing/Imaging

Blood pressure, HR, etc.

Radar imaging techniques

High penetration in tissues

Beams with mm range

Localization/Tracking

Distance measurements

Accuracy in the mm scale

Active echo engine

Algorithms of localization

Signal Proc./Commun.

Channel Modeling

Joint source-channel coding

Modulation, pulse shaping

Cognitive networks

UWB radio interfaces for on-body sensor network

EEG

ECG

EMG

SpO2

Patient monitor

WBAN controller

Relay node

PDA

IR-UWB

3.1–4.8 GHz

MB-OFDM UWB

3.1–10.6 GHz

In-body sensor network

CAPSULE ENDOSCOPE

LOW DATA RATE

IMPLANT SENSOR

TO THE WIRELESS BODY AREA

NETWORK CONTROLLER

TO THE PATIENT

MONITOR

IR-UWB

3.1–4.8 GHz

Heart applications – leadless pacemaker, etc. Brain applications – Parkinson, Alzheimer, etc.

Capsule video endoscope

• Use for examination of gastrointestinal track for bleeding, inflammation, tumor, cancer, etc. – ca. 15% of male and female above 50 years old

are likely to get colorectal cancer

– early detection can cure or extend the life with a

few years – screening the entire population above 50 years!

• Fiber optic cable – problems to reach small intestine – huge discomfort for the patient!

Wireless capsule endoscopy

• Capsule Endoscope

A small camera the size of a pill that can be swallowed

Enables visual inspection of small intestines

Diagnosis of gastrointestinal diseases

Significantly less discomfort to patients

• State of the Art

Trasmits still pictures (external video construction)

Slow motion (typically 8 hours)

No navigation system

Localization and tracking with accuracy in the centimeter scale

Required characteristics for improvement

• High data rate

73.8 Mbps for raw HD data

• Extremely low power consumption

On the order of 1 mW

• Circuitry simplicity/integrability

0.18 m CMOS technology

• Reduced physical dimension

11 mm × 26 mm2

• Electromagnetic radiation safety

SAR limits, overheating below 1 °C

Impulse Radio Ultra Wideband (IR-UWB)

Technology

15

Capsule Endoscope Particularly useful for inspection of the small bowel

Example of Capsule Endoscope Video Capsule endoscope video quality (256 × 256 pixels, 2 fps)

17

Experimental Feasibility Verification A series of in-vivo video transmissions in porcine chirurgical models

Transmission Characteristics

UWB transceivers

4224–4752 MHz, 528 MHz bandwidth

80 Mbps, 1280×720 pixel/30 fps

Wireless full HD video transmission

• See the demo at http://www.melody-project.info

GB 1220466.5 Video Camera Pill Opportunities to commercialize the invention

Size: 11 × 26 mm Transmission frequency: 402405 MHz Bandwidth: 300 kHz Data Rate: 800 kbps Image Rate: 2 to 10 fps Image Resolution: 256 × 256 pixels Power consumption: 100 mW Operating life: 8 hours

Size: less than 11 × 26 mm Transmission frequency: 1063–3841 MHz Bandwidth: at least 500 MHz Data Rate: 80 Mbps Image Rate: 30 fps Image Resolution: 1920 × 1080 pixels Power consumption: estimated 1 mW Operating life: more than 8 hours

Possibility of smaller batteries Possibility of remote control

Video compression: Encoder

• Frame-by-frame video coding applied due to low complexity requirement: limited size and limited power- and storage capacity

• Capsule moves slowly → can reduce frame rate to 10-15 fps. Frame interpolation in receiver enhances viewing experience

• Each frame should be coded with as low a rate as possible while maintaining adequate quality

• Coder built on: Differential pulse coded modulation (DPCM) which removes correlation between pixels

Very Low Complexity Low Rate Image Coding for the Wireless Endoscope, US 61/717,963

Video coding: Encoder architecture

Original vs. compressed

Original Compressed

0.67 bpp with 2x2 decimation: Compression ratio ≈ 97%

Localization

– Need to know where anomalies are located

– Adapt frame rate

– Control transmission power and save energy by turning device on and off

Methods for in-body localization

• Electromagnetic: (Received signal strength) PPM has constant amplitude. If path loss is known →

Received signal strength from several sensors indicated where capsule is

– RF power undergoes extreme link dependent shadowing

• Fixed magnetic field (Ferro magnet) – Magnetic field not absorbed by human body

– Can determine orientation of capsule as well

– Possibility to steer capsule from outside

– On-board magnet makes endoscope larger and heavier

Results: Localization

• Cramer-Rao lower bounds calculated for electromagnetic- and magnetic based localization

• Electromagnetic: Localization accuracy to 1 cm

• Magnetic: Localization accuracy to 2 mm

• Tracking of capsule makes localization more accurate. Principle built on multi-model Kalman filtering and matched filter detection

Application of medical radar

Medical radar measurements of human heart

• Penetrating human body with body-contact antennas

• Useable frequency range: 0.5 – 3 GHz

1 GHz CW Radar measurements, single channel

The phase is related to the motion of the heart. The instantaneous frequency is related to the velocity of the heart movement.

Radar (blue curve) ECG (red curve)

Radar imaging UWB radar (0.5 – 3 GHz) Antenna array Combining UWB measurements from the elements of the antenna array gives a radar image

Antenna

Time-lapsed imaging results

Heartbeat signals at different locations

Images are sequenced to a video with frame rate 25 Hz

Principle for Measurements (1) Quasi-linear relationship between radius r(t) and pressure P(t)

Multiple clutter objects

Results on blood pressure estimation

• The backscattered signal from the aorta contains necessary information for estimating its diameter in time and frequency domains.

• Trade-off between high frequency and bandwidth in order to achieve high resolution; high frequencies involve high attenuation.

• Optimal points have been identified with good specificity and accuracy.

• Studying to remove ”artifact” due to the physical heart motion embedded in the contraction/dilation cycle of the aorta.

Concluding remarks • Demonstrated that UWB technology for

– Wireless capsule endoscope • Ultra low power communication architecture

– source coding, channel coding, pulse shapes, modulations, and extremely simpler transmitter and simple receiver architectures based channel model and channel state information

– new MAC protocol, cognitive network architecture, white-space detection scheme, and resource allocation (frequency, power)

• Algorithms for localization and tracking for both electromagnetic (1 cm) and magnetic schemes (0.5 mm)

– Medical radars for heart rate with finer details of opening and closing of heart

values, preliminary studies on blood pressure estimation

• New design architecture for the future wireless capsule endoscope:

– diagnostics • improved imaging sensor for anomaly detection, RF based tomography for cancer tissue

imaging • targeted drug delivery: wireless control with improved localization and tracking using

diversity techniques and range estimation (multiple receivers, path loss, etc.) power control/transmission, nano particles, etc.