Centre for Physical Electronics and Quantum Technology
Centre for Physical Electronics and Quantum Technology
Contents of Presentation
Non-Invasive Human Body Electrophysiological
Measurements using Displacement Current
Sensors
• The Electric Potential Sensor
• Applications to Body Electrophysiology
C. J. Harland, T. D. Clark and R. J. Prance
• Examples of ECG, EEG and EOG
Centre for Physical Electronics and Quantum Technology
• High resolution ambulatory ECG
School of Science and Technology
University of Sussex
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Centre for Physical Electronics and Quantum Technology
The Electric Potential Sensor
Surface of Body
or Head
Surface of Body
or Head
Sensor
Electrode
Electrometer
Amplifier
id
Output
The Electric Potential Sensor
Surface
of
Body
Sensor
Electrode
Electrometer
Amplifier
Feedback
Guard
Output
Voltage
Follower
Amplifier
Output
Insulator
d
Probe
Electrode
id
Air-Gap
Bias Current
Path
Contact Mode
Remote Mode
(id = displacement current)
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4
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Centre for Physical Electronics and Quantum Technology
The Electric Potential Sensor
The Electric Potential Sensor
Features
Applications
• A ‘perfect’ voltmeter
• Geographic surveying
• Measures spatial electric potential or field
• Materials and device testing
• No electrical contact - no charge current
• Electric potential microscopy
• Non-invasive and biocompatible
• Security
• Room temperature operation
• Electrophysiology – ECG, EEG, EOG…
• Scalable
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Centre for Physical Electronics and Quantum Technology
Electrophysiological Applications
Electrophysiological Applications
Remote (off-body) mode
Contact mode (electrically isolated)
Electric Potential Sensor
Electric Potential Sensor
e.g. High Resolution I-Iead ECG
e.g. Remote Monitoring of Heartbeat
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from the fingertips
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Centre for Physical Electronics and Quantum Technology
Electrophysiological Applications
Remote (off-body) mode
Monitoring heartbeat at distances up to 1m
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EOG
EEG
SaO2 timing reference
(mV)
b
0
ECG detected 5cm off-body
c
Electric Potential Sensor
Electric Potential Sensor
Heartbeat detected 30cm off-body
a
5
-5
ECG from contact finger probe
d
-10
0
1
2
3
4
0
5
1
2
Time (s)
3
4
5
Time (s)
Heartbeat at 0.5m
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Centre for Physical Electronics and Quantum Technology
Surface contact mode
Surface contact mode
0.4
0.3
0.3
0.2
0.2
0.1
0.0
-0.1
-0.2
0.0
0.4
2.0
3.0
Time (sec)
4.0
5.0
0.1
0.0
-0.2
0.0
R
0.3
0.2
0.1
T
P
0.0
-0.1
1.0
I-lead ECG from fingertips
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High resolution ECG
ECG (mV)
0.4
ECG (mV)
ECG (mV)
High resolution ECG
Q
-0.1
1.0
2.0
3.0
Time (sec)
4.0
-0.2
0.0
5.0
V4-lead ECG from chest
0.5
1.0
Time (sec)
S
1.5
2.0
Surface His Identification
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3
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Centre for Physical Electronics and Quantum Technology
High resolution EEG
High resolution EEG
EEG through the hair with no scalp preparation
EC
a
Beta
Time domain
0
-40
EEG from occipital
region of brain
showing α-blocking
EEG (µV)
EEG (µV)
Alpha
Eyes Closed
1
2
(sec)
4
7
EEG from occipital
region of brain
showing α-blocking
8
(sec)
0
(EC = Eyes Closed, EO = Eyes Open)
EC
EO
EO
EC
-40
EC
Eyes Open
0
0
a
EO
+40
3
+40
3
4
Time (sec)
5
6
7
5
10
Time (sec)
15
20
20
b
18
16
Frequency (Hz)
b
Relative Amplitude
Eyes Closed
(Alpha)
Frequency domain
5
10
15
20
Frequency (Hz)
Joint time-frequency spectrogram
(red regions show α rhythm)
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10
8
6
4
Eyes Open
(Beta)
0
14
2
0.0
25
4.6
9.2
13.8
Time (sec)
18.4
23.0
30
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Centre for Physical Electronics and Quantum Technology
High resolution EEG
Electro-oculography (EOG)
Remote mode (hair to sensor air gap)
a
EEG (µV)
+40
Beta
Time domain
0
-40
EEG from occipital
region of brain
showing α-blocking
Electro-oculogram
Eyes Open
0
be346.opj : cjh : 20/07/01
Alpha
X
Eyes Closed
20
40
60
Time (sec)
UL
80
100
C
UR
C
DR
C
DL
C
Y
b
Relative Amplitude
0
15
5
10
15
20
Frequency (Hz)
2
3
4
5
6
7
8
Frequency domain
Eyeball movement
Eyes Open
(Beta)
0
1
Time (s)
Eyes Closed
(Alpha)
25
30
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Centre for Physical Electronics and Quantum Technology
Electro-oculography (EOG)
Electro-oculogram
Ambulatory ECG
be342.opj : cjh : 20/07/01
X
Wrist mounted sensors
Y
R
Wristwatch
Style Sensors
UHF Radio
Transmitter
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
L
Time (s)
Laptop
Computer
PCMCIA
Interface
UHF Radio
Receiver
Differential
Amplifier
Eyelid movement
Wireless ECG monitor
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Centre for Physical Electronics and Quantum Technology
Ambulatory ECG
Ambulatory ECG
using wrist mounted sensors in wireless configuration
0.4
ECG (mV)
0.3
0.2
0.1
1.0
0.0
9
(sec)
11
29
(sec)
31
49
(sec)
51
-0.1
0.5
1.0
2.0
3.0
Time (sec)
4.0
5.0
ECG(mV)
-0.2
0.0
I-lead ECG
0.0
Sedentary
-0.5
0
19
10
Ambulatory
Moving
20
30
Time (sec)
40
T
50
T
60
20
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Centre for Physical Electronics and Quantum Technology
Centre for Physical Electronics and Quantum Technology
References
Summary
1) Electric potential probes - new directions in the remote sensing of the human body.
C. J. Harland, T. D. Clark and R. J. Prance. Meas. Sci. Technol. 13 (2002) 163.
• a new sensor for human body electrophysiology
• non-invasive, electrically isolated, biocompatible
2) Remote detection of human electroencephalograms using ultrahigh input
impedance electric potential sensors.
C. J. Harland, T. D. Clark and R. J. Prance. Applied Physics Letters 81 (2002) 3284.
• remote and contact modes
• has been applied to ECG, EEG, EOG
3) High resolution ambulatory electrocardiographic monitoring using wrist mounted
electric potential sensors.
C. J. Harland, T. D. Clark and R. J. Prance. Meas. Sci. Technol. 14 (2003) 923.
Current and future work
• sensor miniaturisation
• new sensor array configurations
Centre for Physical Electronics and Quantum Technology
• investigation of ‘new’ signals
School of Science and Technology
University of Sussex, Brighton, Sussex, BN1 9QT, UK
• commercialisation
[+44] (0)1273 678087
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t.d.clark@sussex.ac.uk
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