TELEMEDICINE

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TELEMEDICINE

• A Mote-based real time health monitoring system

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Introduction

• Cardiovascular disease has been the number one
  killer in the United States for every year since
  1900, and according to the American Heart
  Association it causes more than 2,500 American
  deaths each day.
• Electrocardiography
• Least invasive technique used to monitor the
  heart. An
• Earliest heart activity was monitored by Kolliker
  and Mueller in 1856.
• In 1903, William Einthoven effectively recorded
  an electrocardiogram using a crude galvanometer.
• Micro-electro-mechanical systems (MEMS) technology

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Introduction

• Smart Dust
• University of California, Berkley developed
  motes.
• Crossbow Technology, Inc. 1995
• TinyOS
• The research and development for the complete
  system is funded by the National Science
  Foundation Community based Partnership for
  Integrated Research and Education (NSF-COPIRE)
  group.

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ECG Theory

• Electrical impulses
• Source of voltage.
• Nerve cells.
• Signal acquisition.
• Lead II
• Measures the potential difference between the
  right arm electrode and the left arm electrode.
  The third electrode (left leg) acts as neutral.
• Most common diseases can be diagnosed using lead
  II
• Figure 1 shows a typical lead II ECG signal

Figure 1 lead II signal
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Noise Sources

• The ECG signal has the amplitude of about 10 mV
  and noise
• measured on the body tissue is of the order of
  10-100µV. Noise
• comes from many low-level sources such as thermal
  noise and
• crosstalk or from biological or environmental
  sources

• Biological sources
• muscle contraction
• baseline drift
• ECG amplitude modulation
• due to respiration
• motion noise.
• Eliminated by using a low pass filter.

• Environmental sources
• electrode contact noise
• instrumentation noise.
• Power line interference
• Eliminated using a notch filter

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Wireless Sensor Networks

• Research on sensor networks started around 1980
  at the Defense Advanced Research Projects Agency
  (DARPA) Distributed Sensor Networks (DSN)
  program.
• Sensor network technology relies on integration
  of technologies from three different research
  areas sensing, communication and computing.
• Radio Frequency
• Made available worldwide
• Industrial-Scientific-Medical (ISM) band 2400 MHz
  2483.5 MHz

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Factors influencing sensor network design
There are six main factors used to serve as a
guideline to design a protocol or an algorithm
for wireless sensor networks. a) Fault
tolerance b) Scalability c) Flexibility
d) Transmission media e) Power consumption
f) Production costs
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Network Topology

• The motes can operate in three types of
  topologies
• Point to Point topology
• Ad-hoc topology
• Hybrid topology
• The Hybrid topology is shown in Figure 2 below.
• Figure 2 Hybrid
  Topology
• Also known as Mesh

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Screen capture of motes operating in Star Topology
Figure 3 Star topology
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Screen capture of motes operating in Hybrid
topology
Figure 4 Hybrid topology
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Routing

• Sensor node (MicaZTM) deployment
• Scattered sensor field as shown in Figure 5
• Routing through the MIB600CATM
• Figure 5 Data
  Routing
• There are two main ways of routing data
• Gossiping
• Flooding

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Routing Protocols

• Two tasks of a routing protocol
• Route discovery
• Route maintenance
• There are 5 main routing protocols
• Negotiation based protocols
• Direct Diffusion
• Energy aware routing
• Rumor routing
• Multipath routing

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TinyOS

• It is an event-driven system
• It is designed to handle a high degree of
  concurrent applications
• The implementation language for the system is
  nested C (nesC).
• Node ID and Group ID

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Hardware Implementation

• The overall system can be broken down into
  smaller subsystems. The three fundamental
  components are the ECG circuit board, the
  wireless system and the monitoring computer.
• System configuration can be seen in the system
  block diagram shown in Figure 6 below
• Figure 6 System Block
  Diagram

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Hardware Implementation

• Actual hardware implementation of the EKG circuit
  board, acquisition unit and wireless sensor
  network is shown in Figure 7
• Figure 7 Hardware
  Implementation

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ECG System

• Electrodes
• Instrumentation Amplifier
• Signal Filtering
• Low pass filter
• Notch filter
• ECG system block diagram is shown in Figure 8
  below
• Figure 8 ECG system block
  diagram

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Wireless System

• The wireless system is supposed to link the data
  acquired from the physical network to a local PC
• Wireless system framework
• First layer Mote layer
• Second layer Gateway
• Third layer Visualization layer
• Figure 9 Wireless
  system

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Wireless System

• The wireless sensor network required to
  accomplish the following six tasks
• i. Data Acquisition
• ii. Encoding data
• iii. Data transmission
• iv. Data reception
• v. Decoding data
• vi. Data Interpretation
• Figure 10 Wireless
  system requirement

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MDA300CATM

• MDA300CATM can be used as a low-power wireless
  data acquisition
• device and it is used to interface with the
  MicaZs.

• 6 Digital channels (D0 D5)
• 7 Single ended Analog channels
• (A0 A6)
• 3 Differential Analog channels
• (A11 A13)
• 4 Differential Precision analog channels
• (A7 A10)
• Internal Channels for onboard sensor
• for temperature and humidity.

Figure 11 MDA300CATM
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MPR2400 (MicaZTM)

• Microprocessor Atmel ATMega 128L
• 128KB flash 4KB SRAM
• Radio Chipcons CC2420
• 250 Kbps data rate
• DSSS encoding, O-QPSK modulation
• 14 Channels 11 (2.405 GHz) - 25
• (2.480 GHz) separated by 5 MHz
• 64 bit Serial ID
• 51 pin expansion connector
• Eight 10 bit analog I/O
• 21 General Purpose digital I/O
• Power Options
• 2 AA cells

Figure 12 MPR2400
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MIB600CATM

• The MIB600CATM Ethernet interface board provides
  connectivity to MicaZTMs for communication and
  in-system programming.
• It has two main functions
• Gateway (mote RF to Ethernet bridge)
• Programming

• Atmel16L In-system processor
• 51 pin Hirose expansion connector
• TCP/IP serial server
• Port 10002
• IP address
• Two power options
• 5 VDC adapter power
• Power over Ethernet

Figure 13 MIB600CATM
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Mote Programming

• Mote Programming can be done in two ways
• Direct programming, where the mote is physically
  connected to the MIB600CATM
• Over the Air Mote Programming (OTAP)
• GoldenImage
• Program is deluge-enabled
• Node 0 programmed
• Advantages of over the air programming
• sensor nodes are deployed in harsh environments
• Programs developed by Crossbow Technology Inc.
• XMDA300CA_LPTM
• TOSBaseTM

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Packet Formation

• The XMDA300_LPTM breaks the data into packets to
  effectively route it to the base station. A
  typical message packet is shown in Figure 14
  below.
• Figure 14 Typical
  message packet
• The MAC Delay is the delay in milliseconds prior
  to transmission. The 8-byte Preamble helps the
  receiver to synchronize its timer to the incoming
  data. The 2 Synchronization bytes indicates the
  start of the data. The typical MicaZTM Tiny OS
  message is 41 bytes long it can be up to 125
  bytes long.

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Packet Formation

• The TinyOS message structure is shown in Figure
  15 below
• Figure 15 TinyOS
  Message structure
• The MicaZTM TinyOS message contains
• Header Payload Length 1
  byte
• Frame Control 2
  bytes
• Sequence Number 1 byte
• Destination
  ID 2 bytes
• TOS
  Address 2 bytes
• TOS AM
  Type 1 byte
• TOS Group ID 1 byte
• Service Data Unit Data Payload 29 bytes
• Frame Check Sum CRC
  2 bytes

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Packet Description

• The XMDA300CA_LPTM program divides the data into
  four packets
• As follows.

Packet 2 data0 sensor id, MDA300 0x81
data1 packet number 2 data2 node id
data3 reserved data4,5 analog adc data
Ch.7 data6,7 analog adc data Ch.8 data8,9
analog adc data Ch.9 data10,11 analog adc
data Ch.10 data12,13 analog adc data Ch.11
data14,15 analog adc data Ch.12 data16,17
analog adc data Ch.13
Packet 1 data0 sensor id, MDA300 0x81
data1 packet number 1 data2 node id
data3 reserved data4,5 analog adc data
Ch.0 data6,7 analog adc data Ch.1 data8,9
analog adc data Ch.2 data10,11 analog adc
data Ch.3 data12,13 analog adc data Ch.4
data14,15 analog adc data Ch.5 data16,17
analog adc data Ch.6
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Packet Description
Packet 3 data0 sensor id, MDA300 0x81
data1 packet number 3 data2 node id
data3 reserved data4,5 digital data
Ch.0 data6,7 digital data Ch.1 data8,9
digital data Ch.2 data10,11 digital data
Ch.3 data12,13 digital data Ch.4
data14,15 digital data Ch.5
Packet 4 data0 sensor id, MDA300 0x81
data1 packet number 4 data2 node id
data3 reserved data4,5 battery
data6,7 humidity data8,9 temperature
data10,11 counter data14 msg4_status
(debug)
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Packets observed

• At the present stage of the project, the data
  packets have been segregated and saved on the
  local machine. One of the subgroups in the NSF
  COPIRE group is presently working on representing
  the packet data visually.
• The sample packets are monitored by running
  Xlisten application on Cygwin.
• Figure 16 Sample
  packets

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Interference Issues

• The license-free 2.4 GHz band encouraged the
  development of different technologies such as
  wireless LAN, Bluetooth and ZigBee. Appliances
  such as microwaves, cordless phones, baby
  monitors also operate in the same frequency
  spectrum.
• The main concern of using this band is the
  possibility of intersystem interference.
• Direct Sequence Spread Spectrum (DSSS) involves
  spreading bandwidth to allow multiple nodes to
  simultaneously use the same bandwidth.
• Advantages of spread spectrum
• Resistance to multipaths fading and narrowband
  jamming.
• Data security

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Security Issues

• Health Insurance Portability and Accountability
  Act (HIPAA) of 1996.
• TinySec is a link-layer security architecture
• Transmitting the data over the Internet,
  protocols such as IPSec, Secure Sockets Layer
  (SSL), Transport Layer Security (TLS) and Secure
  SHell (SSH) secure communications.
• Sensor networks are susceptible to environmental
  or intentional physical attacks such as
• node capture
• physical tampering
• denial of service

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Applications

• Sensor networks may consist of many different
  types of sensors and
• can be used for continuous sensing, event
  detection and location
• sensing, due to this, they can be used to cater
  to diverse health related
• applications.
• Wearable health monitoring systems
• Data indicating an imminent medical condition, an
  emergency service can be notified.
• Patients with either chronic conditions or who
  are undergoing supervised recovery can be
  monitored from the comfort of their own homes.
• Wireless sensor nodes could also be used to
  locate doctors and nurses within hospitals.
• In pharmaceutical applications, sensor nodes
  could be used to track shipments
• Military applications

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Future Development

• Presently the project is still in the software
  development phase and the NSF-COPIRE group is
  working on logical representation of the data on
  the local PC or a handheld device like a PDA and
  creating a database.
• In the future, using the Mica2DotTM motes instead
  of the MicaZs to increase the portability of the
  system.
• Figure 17 shows the Mica2DotTM mote in comparison
  to a US quarter.
• Figure 17
  Mica2DotTM
• The ultimate goal of this system is relaying the
  vital data to doctors and emergency medical
  technicians and ambulance systems.

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Conclusion

• The NSF COPIRE project has taken the first step
  towards the next major advance in the evolution
  of cardiology. The prototype consists of reduced
  cabling and reduced configuration issues.
• The current state of the project is a platform on
  which design enhancements can be made, the
  proposed end product is very realistic and
  attainable.
• In the future, wireless health systems could help
  to meet the health needs of the entire household.
  This will lower the cost of healthcare and
  effectively preventing a public health crisis.
• Wireless sensor networks, in future, will be an
  integral part of our lives, monitoring multiple
  health related signals and offering faster
  response times.
• As TinyOS is a public / open source domain, it
  will unify academic and industrial research
  efforts, thus, improving sensor networks.

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NSF COPIRE group
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Demonstration
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Questions
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Thank you