DANIEL BRAUNWORTH
Instrumentation Segment Manager
Intelligent Sensing for
Environmental and Process
Measurement
1
1/24/2019
MICHAL RANINEC
Systems Applications Engineer

Real-time Measurement Advances Our Quality of Life
►Environment
►Process monitoring
►Materials quality
►Early failure detection
►Safety

Foundational Measurement Concern: Analysis Reliability
3
There is a lack of confidence in
instrument performance,
often seen as being inconsistent,
with operation and maintenance
requiring highly specialized support.
”
“
—Water Environment Research
Foundation

Future
The Smart Sensing Revolution
Digitize the
sensors
Reduce the
maintenance
Expand the
network
Advance
the data
analytics
Sensing
System
SENSORS
SIGNAL
PROCESSING
& SENSOR
DIAGNOSTICS
POWER
CLOUD
SECURITY
COMMUNICATION
Today

Broader Sensing Networks Enable Better Monitoring and Control
►Greater benefits from intelligent sensors
►Network-level assessments
►Increased spatial resolution
Expanding wireless networks
demand reduced power and
increased reliability

Making Electrochemical Sensors Intelligent
Increases Measurement Reliability and Reduces Total Cost of Ownership
6
Vision: Fully Integrated, Easy to Use, Plug ‘n’ Play Sensors
“Analyte In, Measurement Out”
Industrial Gas Sensing
Water Quality & Liquid Analysis
Environmental Air Quality
Signal Conditioning
& Data Conversion
Sensor(s)
Smart Sensor
Digital
Processing &
Control
Embedded Compensation, Calibration, Data Fusion,
Diagnostics / Prognostics / Extended Life
Smart interrupts
Memory/
FIFO
ADUCM355
I2C/SPI/UART..
Reliable measurements in real-world conditions
Temperature - Humidity - Contaminants
Handling - EMC

Liquid Analysis

Electrochemical: The Smart Sensor of Choice for Water Quality Analysis
8
Colorimetric / Titrimetric
Nephelometric /
Turbidimetric
Electrochemical
Microbiological
Luminescence, Absorbance,
Fluorescence
Trace Analysis /
Lab Methods
Disadvantages
Sensor fouling, aging
& maintenance
Calibration
Environment
compensation
Drift over life
pH
Oxidation-
Reduction Potential
Conductivity
Ion Selective
Electrodes
Dissolved Oxygen
Advantages
Most common
indicators
Low power
High resolution
Linear output
Economical
Intelligent EC sensing
• Enables continuous & real-time
sensing without reagents
• Utilizes long proven sensor
technology
• Diagnoses or overcomes
traditional EC disadvantages

Electrochemical Liquid Sensors – Basic Principles & Operation
9
RTD Connections
RTD Connections RTD Measurement
RTD Measurement
ADC
High Input Impedance
Op Amp
High Input Impedance
Op Amp
ADC
Vref
RTD Excitation
Conditioning
RTD Excitation
Conditioning
ISO
pH Probe
Reference junction
Internal reference electrode
Inner buffer solution
Reference electrolyte
Temperature sensor
Indicating electrode
Electrodes
AC Excitation
AC Excitation
DAC
Precision Transimpedance
Amplifier
Precision Transimpedance
Amplifier
ADC
Conductivity cell housing
Potential Sensors
(e.g. pH, ORP, ISE)
Impedance or Current Sensors
(e.g. Conductivity, DO)
Proper Operation Requires:
► Routine calibration against a
standard buffer solution
► Clean sensing surface
► Operation within specified
sensor range
► Temperature compensation
► Precision, low noise, low drift
measurement electronics

Biggest Market Expansion Barrier: Maintenance Costs
10 ©2018 Analog Devices, Inc. All rights
reserved.
In-line pH measurement is
perceived as being one of
the most difficult process
analytical measurements
to implement.
”
“
— literature from a top pH probe
manufacturer

Reducing Maintenance Cost Requires Diagnostic Measurements
11
Frequent calibration requirements
(environment & electrode stability)
Sensor breakage & wear-out
(membrane replacement, etc.)
Sensor cleaning & maintenance
(fouling / film growth)
Associated Diagnostic Measurements
Common Measurement Problems
• Calibration health self-test for user alert
• Sensor health – signal validity
• Sensor health – signal integrity
Need: Sensor-integrated diagnostics electronics with
complete electrochemical measurement toolbox

Small Signal Diagnostic Testing: Electrochemical Impedance Spectroscopy
12
Double Layer Capacitance
Electron Transfer Resistance
Uncompensated
(electrolyte)
Resistance
-2.00E+02
3.00E+02
8.00E+02
1.30E+03
1.80E+03
2.30E+03
0.00E+00 5.00E+02 1.00E+03 1.50E+03 2.00E+03 2.50E+03 3.00E+03 3.50E+03
-Imag
(Ohm)
Real (Ohm)
Ru Ru + Rp
High Freq Low Freq
Nyquist Plot
Randles Cell
(Simplified)
RU
RP
CDL
Other large signal EC techniques:
• Voltammetry (e.g. CV, square wave)
• Chronoamperometry

pH Probe Impedance Spectroscopy Reveals Probe Condition
Impedance of various solutions Impedance change with pH sensor dry-out

CN0428 – A Programmable Liquid Analysis Reference Platform
Water quality solution enables
platformization in low power, small
footprint designs
► Sensor health analysis made possible through
integrated measurement & diagnostic functions
► Very low power, integrated measurement platform
adaptable to probe form factor
 Measures pH, Conductivity, ISE, ORP
► Programmable liquid analysis daughter boards
 AFE and measurement pre-processing with
ADuCM355
 Integrated compensation (ATC)
Hardware, software and documentation
► Based on ADICUP3029 development platform
► Software examples available on analog.com
► Circuit Note and user guide
www.analog.com/cn0428

Gas Sensing

Gas Sensing Technologies
16
Catalytic Sensors
(pellistor, thermoelectric)
Thermal Conductivity
Sensors
Electrochemical
Optical & Infrared
Sensors
Semiconductor Sensors
(metal oxide)
Acoustic Wave Sensors
Advantages
Low power
High resolution
Linear output
High accuracy
Economical
Disadvantages
Temperature & Humidity
dependency
Limited shelf life
Cross-sensitivity
Drift over life
Requirements for
Proper Operation
► Temperature and
humidity range
► Stable bias voltage
► Avoid exposure to
high concentration of
target gases, VOCs,
dust and oil mist
► EMC and Functional
Safety compliance Ammonia
Carbon
Monoxide
Hydrogen
Sulphide
Nitrogen
Dioxide
Oxygen
Ozone

Electrochemical Gas Sensors – Basic Principles & Operation
17
► Measuring current proportional to target gas concentration
generated due to oxidation or reduction at sensor electrodes
► Most common electrode configuration:
► Sensing (working) – SE (WE)
► Reference - RE
► Counter - CE
► Stable bias voltage is required between RE and SE (WE)
Basic signal chain

Biggest Market Expansion Barrier: Sensor Lifetime
18 ©2018 Analog Devices, Inc. All rights
reserved.
Strong support by
wireless network design,
longer battery life,
implementation, and
maintenance are the key
services demanded by
end users in the current
phase of technological
development.
”
“
— Frost & Sullivan

Reducing Maintenance Cost Requires Diagnostic Measurements
19
Frequent calibration requirements
(electrode stability & electrolyte health)
Sensor breakage & wear-out
(oxidation on contacts, electrolyte leakage ...)
Open/Short circuit between sensor contacts
(sensor disconnected from device …)
Associated Diagnostic Measurements
Common Measurement Problems
• Calibration health self test for user alert
(Impedance Spectroscopy, Ramp Test)
• Bias Voltage Ramp Test and Pulse Test
• Bias Voltage Pulse Test
Need: Sensor-integrated diagnostics electronics with
complete electrochemical measurement toolbox

Sensor Diagnostics I
Electrochemical Impedance Spectroscopy (EIS)
► Applying AC signal sweep on sensor electrodes
 Detects aging of sensor’s electrolyte
 Diagnoses charge transfer between electrodes
► Good correlation between impedance and
sensitivity
► On-chip EIS enables long term drift
compensation, end of life prognostics and other
smart sensor features
20

Sensor Diagnostics II
Pulse and Ramp Test
► Pulse Test (Chronoamperometry)
 Applying voltage pulse on top of bias voltage
while monitoring the sensor’s output
 Tests sensor responsivity
► Ramp Test (Cyclic Voltammetry)
 Voltage applied on top of bias is ramped in
steps
 Diagnoses electrolyte and charge transfer
health
21
time
voltage
VBias
current
time
Good
Sensor
Poor Quality
Sensor
Poor Quality
Sensor
time
voltage
VBias

CN0429 – A Programmable Gas Sensing Reference Platform
22 www.analog.com/cn0429
Smart EC gas sensing platform enables
integrated, low power, digital gas sensors
► Sensor health analysis made possible through
integrated measurement & diagnostics functions
► Measure any four EC gas sensors
(in “4-series” form factor)
► Programmable gas sensing daughter boards
 AFE and Signal Processing with ADuCM355
 On-Board Temperature & Humidity sensor
Hardware, software and documentation
► Based on ADICUP3029 development platform
► Software examples available on analog.com
► Circuit Note and user guide

ADuCM355
Integrating Intelligence at The Core

ADuCM355 Precision Microcontroller
Industry’s Most Advanced Chemical Sensor Interface IC
► Low Power, High Precision Sensor Measurement Platform
 Voltage, Current and Impedance Measurement capabilities
► Advanced Sensor Diagnostic Capability
 High Speed Waveform Generator
 Impedance Spectroscopy Engine
► Ultra-Low Power Cortex™ M3 Processor
 Algorithms, data post-processing, communication, security
Available Collateral:
► Datasheet & Hardware Reference Manual
► ADuCM355 Evaluation Kit
► 3rd party module solutions
► 3x Circuit From The Lab® Reference Design
 Multi-sensor system reference design (CN0428, CN0429)
 EMC compliant reference design (CN0425)
24 www.analog.com/aducm355
Applications:
• Gas detection
• Water quality analysis
• Biosensing analysis
• General environmental sensing (air, water, soil)

Complete Onboard Electrochemical Measurement Toolbox
Feasible Measurement Functions with CN0428 & CN0429:
Possible Functions w Added Drive Circuit:
*Example projects from ADI available
Amperometry
• Multistep Amperometry (MA)
• Chronoamperometry *
• Pulsed Amperometric Detection (PAD)
• Fast Amperometry (FAM)
• Zero Resistance Ammeter (ZRA)
Voltammetry
• Linear Sweep Voltammetry (LSV)
• (Differential) Pulse Voltammetry (DPV)
• Square Wave Voltammetry (SWV)
• Normal Pulse Voltammetry (NPV)
• AC Voltammetry (ACV),
Cyclic Voltammetry (CV) *
Potentiometry
• Multistep Potentiometry (MP)
• Chronopotentiometry
• Stripping Chronopotentiometry (PSA or SCP)
• Open Circuit Potentiometry (OCP)
Electrochemical Impedance Spectroscopy (EIS) *
Stripping Voltammetry
• Anodic/cathodic/adsorptive

Summary
The environmental and process measurement market growth will
implement smart sensors and expand sensing networks to take
advantage of advanced data analytics
26
Integrated measurement and diagnostics is now possible in
platformized, low power, compact point-of-sensing solutions
Intelligent sensors reduce maintenance and cost of ownership

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