Transcript Potentiostat_midterm_pres_fall2011_10

Team Members:
Kyle Bloomer
Josh Geiman
Lucas Bennett
Team Sponsor:
Dr. Cindy Harnett
Team Mentor:
Dr. Andy Dozier
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Dr. Harnett's laboratory needs 15 potentiostats for her
microfluidics lab
Off the shelf potentiostats range in price from $5K to
$10K, which is prohibitive for an instructional lab
Commercial Potentiostat
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A Potentiostat is the electronic hardware required to
control a three electrode cell and run most electroanalytical experiments.
An electronic instrument that controls the voltage
difference between a Working Electrode and a Reference
Electrode.
It measures the current flow between the Working and
Counter Electrodes.
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A previous potentiostat was attempted by a project team
using an open source design, the Ardustat
The Ardustat was a two electrode configuration
Ardustat electrical design was poorly documented,
which caused the project team to have difficulty
implementing it for the project
Software design was “spaghetti code”, and it had no
documentation or comments for either the firmware or
the application software
Hardware used was an Arduino processor board, with a
prototype “daughter board”
The team was unable to meet the project goals
Before Ben
After Ben
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An MEng student has implemented the
hardware using a PCB assembly, and gotten it
to work
The existing code has been reverse
engineered and documented/commented
BUT the Ardustat is a two electrode
configuration, and the software GUI is very
limited in its capabilities
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We have found an open source, three
electrode potentiostat, known as the
“Cheapstat”
Cheapstat was developed by UC Santa
Barbara to provide an affordable
alternative to COTS potentiostats
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Input parameters must be set through an
onboard LCD and 5-way joystick
The display is very limited
◦ LCD on the Cheapstat processor “box”
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Provides multiple measurement modes
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Square Wave
Linear Sweep
Stripping
Cyclic Voltammetry
Front Panel
PCB Assembly
Joystick
To Cell
Electrodes
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Design and implement a three electrode
potentiostat, based on the Cheapstat
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Easier to use interfaces
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GUI on a PC
No joystick
Ease of assembly and use by students, faculty, and
staff
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Three electrode design
PCB assembly techniques
USB processor to PC interface
External power sources
Full documentation of hardware
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Schematics
Simulation results
Assembly diagrams
List of Materials
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Develop GUI and firmware using modern
software engineering techniques
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No spaghetti code
Comment all code
Provide a software library
Document all the application software and
firmware
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Installation notes
User’s Manual
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Characterize electrical performance for a typical
electrochemical device
Compare electrical measurements with the
existing Ardustat
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Two electrode vs. three electrode measurement
differences
Data/Display
Management
System
120VAC
60Hz
15A
USB
Processor
Voltage Converter
Device Under
Test
(DUT)
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Processor
◦ Firmware
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Display/Data Management System (DDMS)
◦ GUI software
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Power supply
Data/Display
Management
System
120VAC
60Hz
15A
USB
Processor
Voltage Converter
Device Under
Test
(DUT)
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Capture the test configuration
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Measurements to be made, ranges, etc.
Execute the test using the measurements that have been
established by the operator
Log and time stamp test results in NVRAM
Send measurement data to Display/Data Management
System (DDMS) during test
When polled by the DDMS, send the test results in CSV
format to a file on the PC
Data/Display
Management
System
120VAC
60Hz
15A
USB
Processor
Voltage Converter
Device Under
Test
(DUT)
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Pre- test Mode
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Test Mode
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Calibrate instrument
Configure processor for the test to be executed
Execute test script that was entered during Pre-Test
Display results during test
Post Processing
◦ Report generation
Data/Display
Management
System
120VAC
60Hz
15A
USB
Processor
Voltage Converter
Device Under
Test
(DUT)
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Three options are available:
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Wall Wart
USB
Battery power
Microprocessor requires 5 VDC
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Estimated 3 watts
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Build and test Cheapstat using current design
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Research ongoing regarding firmware development
environment
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CheapStat Parts have been ordered
Software development kit to preserve schedule
Test existing Ardustat
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Need DUT – Chlorine Generator?