lecture 11 - weber state universityapplications of wearable biosensors chemical and vital sign...
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
ECE 5900/6900: Fundamentals of Sensor Design
Lecture 11Biomedical Sensor Systems & Biosensors
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Biomedical Sensors and BioSensors
Q: What are biomedical sensor systems?
A: Sensor systems that measure vital signs such as ECG
signal (blood pressure, pulse rate), body temperature,
respiration rate and enzyme levels for glucose levels etc
Q: What are biosensors?
A: Biosensor=bioreceptor+transducer
Biosensor is made up of bioreceptor which is a
biomolecule that recognizes target analyte and
transducer that converts the target event/species into
measurable signal
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Biomedical Sensor Systems
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Biomedical Sensor Systems
Blood Pressure Monitor
Pulse Oximeter
Respiratory Monitor
ECG Monitor
Omron
BP792IT
Covidien
Nellcor
System
Strong
Digital
Handheld
Pulse
Oximeter
703A
Heal Force Prince 180B
Portable ECE Monitor
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Biomedical Sensor Systems
Ultrasound
Machine
Defibrillators
Portable X-Ray Machine
Xavier
portable
x-ray
GE Voluson
E10
Phillips Heartstart XLdefibtech
Lifeline
AED
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Biomedical Sensors
Ref: Q-CPR® Measurement and Feedback with CPR meter, Application Note by Phillips
1) Provide audio/visual feedback to
the CPR giver
2) Chest compression sensor
measures compressions and
ventilations connected to the
defibrillator
CPR Meter and Emergency Medical Attention
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Biomedical Sensors
Ref: Lionsgate technologies (LGT Medical)
1) Pulse Oximeters measure Oxygen levels in blood and heart rate
2) Measure oxygenation level for intensive care, operating, recovery, emergency and
hospital ward settings, pilots in unpressurized aircraft
Pulse Oximeter and Oxygenation Level
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Biomedical Sensors
Ref: TE Connectivity and GE Healthcare
1) Ultrasound systems perform nondestructive testing of body structures and
provide medical imaging
2) Visualize subcutaneous body structures including tendons, muscles, joints,
vessels and internal organs for possible pathology or lesions
Ultrasound and Diagnostic imaging
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Biomedical Sensors
Ref: TE Connectivity and GE Healthcare
1) AEDs can measure heart signals and send out electric shock as
needed
2) AEDs can save lives!
Automatic External Defibrillator (AED) and Restoration of Heart Rhythm
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Types of Biomedical Sensor Systems
ECG Signal Monitor
Glucose Sensor
Ultrasound Machine
Defibrillator
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Electric System of Heart
Ref: https://www.uahealth.com/library/sections/article/electrocardiogram-ekg-stress-test-holter-monitor
1) ECG Signal is a sum of many different heart signals (cell potential)
2) Heart can be viewed as time-varying voltage source with amp= sum of
cardiac cell potentials and freq= cardiac cycle
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
ECG Signal: Abnormalities
Normal
Tachycardia: fast heart rate
Extrasystole - Premature Beat
Ventricular fibrillation: uncoordinated
ventricular contractions
Complete heart block: signal from atria not
reaching ventricles which beat on their own
Myocardial Infarction: disruption due to death
of tissue
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
ECG Signal Amplifier Circuit#1Goal: Amplify the raw ECG signal level while suppressing noise
1) Right Leg (RL) drive circuit reduces interference and DC offset out of the
differential amplifier.
2) RL drive circuit inverts and amplifies the average common mode signal back
into the patient’s right leg and creates a cleaner ECG output signal.
3) Larger feedback gain improves the common mode rejection ratio (CMRR)
Typical ECG signal amp=between 10uV and 5 mV, bandwidth=between 0.05 and 100.00 Hz
+-
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
ECG Signal Amplifier Circuit#3Goal: Amplify the raw ECG signal level while suppressing noise
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
ECG Signal Noise and Artefacts
Power line noise snubber
(60 Hz Bandpass Filter)
Most artefacts
can be filtered digitally
[1] ECG Signal Amplifier Circuit: http://www.egr.msu.edu/classes/ece480/capstone/spring13/group03/documents/ElectrocardiographyCircuitDesign.pdf
http://www.cisl.columbia.edu/kinget_group/student_projects/ECG%20Report/E6001%20ECG%20final%20report.htm
[2] Labview VI: http://www.ni.com/tutorial/6349/en/
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Types of Biomedical Sensor Systems
ECG Signal Monitor
Glucose Sensor
Ultrasound Machine
Defibrillator
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Glucose sensor
Thermistor
Control, Working and
Reference Electrodes
Amperometry Circuit
Glucose -> Glucose Oxidase -> Ions -> Change in Current (3 μA)
fc = 100 HzTest Strip
Test Strip
MeterTiny
blood drop
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Types of Biomedical Sensor Systems
ECG Signal Monitor
Glucose Sensor
Ultrasound Machine
Defibrillator
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Ultrasound Basics
1) Transducers generate ultrasound waves (2 -18 MHz), which are sent to the
tissue and internal organs by creating better acoustic coupling with ultrasound gel
2) Ultrasound waves hit a boundary between tissues, part of the sound waves get
reflected back to the transducer while some sound waves propagate further until
they hit another tissue boundary and get reflected
3) By receiving and processing the echoes, the 2D and 3D image of the internal
organs and structures can be formed
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Ultrasound Imaging System: Microchip
Ref: Microchip http://www.microchip.com/pagehandler/en-us/technology/ultrasound/home.html
Generic Ultrasound System
Phased array transducers (32 to 256 transmitter/receiver pairs)
High Voltage Analog Switch, High Voltage Transmitter,
High voltage FET and FET Array, FET Driver, Arbitrary Waveform
Generator, and T/R Switch.
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Ultrasound Imaging System: Maxim Integrated
Ref: Maxim Integratedhttps://www.maximintegrated.com/en/app-notes/index.mvp/id/4696
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Ultrasound TransmitterHigh Voltage Analog Switch:
1) Acts as multiplexer to dynamically connect a specific transducer element
to a specific transmitter/receiver (Tx/Rx) pair.
2) Must handle voltage swings as large as 200VPP and with peak currents
up to 2A.
High Voltage Transmitter:
1) Transmitter beamformer typically generates the necessary digital
transmit signals with the proper timing and phase to produce a focused
transmit signal
2) Arbitrary waveform generator is used to opimize image quality: the
transmitter generates digital 8-bit to 10-bit words at rates of
approximately 40MHz to produce the required transmit waveform.
Digital-to-analog converters (DACs)
1) DACs are used to translate the digital waveform to an analog signal,
which is then amplified by a linear high-voltage amplifier to drive the
transducer elements
Ref: Maxim Integratedhttps://www.maximintegrated.com/en/app-notes/index.mvp/id/4696
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Ultrasound Receiver
Ref: Maxim Integratedhttps://www.maximintegrated.com/en/app-notes/index.mvp/id/4696
Tx/Rx switch
1) Protects the LNA from the high-voltage transmit pulse and isolates the
LNA's input from the transmitter during the receive interval.
2) Diodes comprise the switch which automatically turn on and off when
presented with a high-voltage transmit pulse
Low-noise amplifier (LNA) and Variable-gain amplifier (VGA)
1) LNA must have excellent noise performance, low-input impedance and
sufficient gain
2) VGA provides the receiver with sufficient dynamic range (100 dB) over
the full receive cycle
3) Must have 30dB to 40dB of gain to amplify the received signal into a
typical 12-bit ADC
Anti-alias filter (AAF) and Analog-to-digital converter (ADC)
1) AAF reduces high-frequency noise (Butterworth or higher-order Bessel
filters)
2) 12-bit ADC at 40Msps to 60Msps
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Types of Biomedical Sensor Systems
ECG Signal Monitor
Glucose Sensor
Ultrasound Machine
Defibrillator
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Defibrillation Basics
1) Normal heart-beat can be restored by delivery of a controlled
electric shock: this process is called Defibrillation
2) Defibrillators include sensors that can detect the cardiac
rhythm and are programmed to deliver a right amount of shock
when required
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Defibrillator
Defibrillation can be performed by anyone
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Defibrillator System
Ref: Texas Instrumentshttp://www.ti.com/solution/automated_external_defibrillator
ECG Monitor
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Defibrillator CircuitThree key components: a high voltage source, a capacitor and
switches.
High Voltage Source
1) A battery drives an oscillator circuit which switches on and off at
1 kHz: the current is fed into transformer which generates about
500 V output
2) The AC signal is rectified by diode and is fed into the capacitor
Ref: Boston Scientifichttp://editions.sciencetechnologyaction.com/lessons/7/105/BostonScientific.pdf
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Defibrillator CircuitThree key components: a high voltage source, a capacitor and
switches.
Storage Capacitor
and Switches
1) High Voltage Caps
2) Switches charge and discharge (to the patient) the capacitor
3) Normal energy output = 125 J with C= 1mF, V=500 V (E = ½ C V2
4) V = 500 V, I=25 A, 10 ms pulse
Ref: Boston Scientifichttp://editions.sciencetechnologyaction.com/lessons/7/105/BostonScientific.pdf
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Biosensors
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Introduction
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Wearable BioSensors
pH Sensor
Glucose SensorHealthpatch Sensor
Glaucoma Pressure/Glucose Sensor
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Wearable Biomedical Sensors
ECG Patch Sensor (biomedical)
Epilepsy Monitor Sensor (biomedical)
IMEC ECG Patch
Dialogue Device byArtefact
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Wearable Biomedical and Biosensors
Fighter Pilot Vitals and Health Status
Human Performance Augmentation (HPA) by measuring heart rate,
skin temperature, and blood pressure in real-time using wearable
biosensors to enhance warfighter performance
AFRL: http://www.wpafb.af.mil/news/story.asp?id=123402193
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Applications of Wearable Biosensors
Chemical and Vital Sign Sensors and Firefighter Saftey
Reduce deaths and disability due to Cardiac stress by tracking heart
and respiration rates, activity levels and posture
CO and CO2
Sensors
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
BioSensors and WBAN
Wearable pH Sensor
Wireless Body Area Network (WBAN)
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Basics of pH Sensing
Q: What do pH sensors measure?A: Sodium, chloride, lactate concentration in sweat produced
during physical exercise and emotional stress
Q: What are the applications of wearable pH sensors?A:
1) Wound monitoring: pH shifts at the wound site can provide
useful information regarding the wound
2) Help doctors diagnose cardiovascular diseases, cystic fibrosis or
others by acquiring physiological information on infants
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Basics of pH SensingMonitor Concentration of Hydrogen Ions
Number of hydrogen ions in water = pH level
1) When an acidic substance ends up in water, it will give up a
hydrogen ion to the water: this will increase hydrogen ions and
lower pH
2) When a basic substance enters the water it will take up hydrogen
ions: this will lower hydrogen ions and increase pH
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Basics of pH SensingPotentiometric pH Sensing
Potentiometric sensors measure change in concentration of
electrons after redox reactions occur at the electrode-electrolyte
interface of an electrochemical cell
Oxidant + Ne- => Reduced product; N=number of electrons
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
pH Sensors: CHEMFETCHEMFET (Chemical FET)
1) Silicon Nitride gate is exposed to the sample solution (e.g. sweat)
2) As H+ ion concentration (pH) changes, the redox reaction changes
the surface charge density at the gate: change in gate voltage
3) This change affects the channel conductance
4) The change in gate voltage is measured as a change in the
drain currentCheck out:
http://www.slideshare.net/RichardYang13/richard-yang-phd-defense-talk
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
pH Sensors: ISFETISFET (Ion Selective FET)
Type 2: Change e-
Concentration in the
Channel Changes Drain
Current
Type 1: Change in
Gate Voltage Changes
Drain Current
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
RFID pH Sensor
Ref: Adhesive RFID Sensor Patch for Monitoring of Sweat Electrolytes by D. Rose, et. al
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
BioSensors and WBAN
Wearable pH Sensor
Wireless Body Area Network (WBAN)
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Smart Sensors and Heath Technology
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ECE 5900/6900 Fundamentals of Sensor Design Dr. Suketu Naik
Smart Sensors and Heath Technology