Potentiostat
description
Transcript of Potentiostat
Potentiostat
Team Members: Kyle BloomerJosh GeimanLucas Bennett
Team Sponsor: Dr. Cindy HarnettTeam Mentor:Dr. Andy Dozier
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
Harnett Lab
Commercial Potentiostat
A Potentiostat is the electronic hardware required to control a three electrode cell and run most electro-analytical 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.
What is a Potentiostat?
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
History - Ardustat
Ardustat Hardware
Ardustat GUI – Connect & Setup
Ardustat GUI – Data Logging
Ardustat Code ExampleBefore Ben After Ben
Previous Project Diagram
Previous Project Test Set
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
Current Status
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
Research
Input parameters must be set through an onboard LCD and 5-way joystick
The display is very limited◦ LCD on the Cheapstat processor “box”
Provides multiple measurement modes◦ Square Wave◦ Linear Sweep◦ Stripping◦ Cyclic Voltammetry
Cheapstat Features
Cheapstat HardwareFront Panel PCB Assembly
Joystick
To CellElectrodes
Design Goals - Hardware Design and implement a three electrode potentiostat,
based on the Cheapstat Three electrode design
Easier to use interfaces GUI on a PC No joystick
Ease of assembly and use by students, faculty, and staff PCB assembly techniques USB processor to PC interface External power sources
Full documentation of hardware Schematics Simulation results Assembly diagrams List of Materials
Develop GUI and firmware using modern software engineering techniques No spaghetti code Comment all code Provide a software library
Document all the application software and firmware Installation notes User’s Manual
Design Goals - Software
Characterize electrical performance for a typical electrochemical device
Compare electrical measurements with the existing Ardustat Two electrode vs. three electrode measurement
differences
Project Goals - Other
ProcessorDevice Under
Test(DUT)
Data/Display Management
SystemUSB
120VAC60Hz15A
Voltage Converter
System Diagram
Processor◦ Firmware
Display/Data Management System (DDMS)◦ GUI software
Power supply
Major Components
ProcessorDevice Under
Test(DUT)
Data/Display Management
SystemUSB
120VAC60Hz15A
Voltage Converter
System Diagram
Processor Requirements Capture the test configuration
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
ProcessorDevice Under
Test(DUT)
Data/Display Management
SystemUSB
120VAC60Hz15A
Voltage Converter
System Diagram
Pre- test Mode Calibrate instrument Configure processor for the test to be executed
Test Mode Execute test script that was entered during Pre-Test Display results during test
Post Processing◦ Report generation
DDMS Requirements
GUI Mockup
ProcessorDevice Under
Test(DUT)
Data/Display Management
SystemUSB
120VAC60Hz15A
Voltage Converter
System Diagram
Three options are available: Wall Wart USB Battery power
Microprocessor requires 5 VDC Estimated 3 watts
Voltage Converter
Build and test Cheapstat using current design CheapStat Parts have been ordered
Research ongoing regarding firmware development environment
Software development kit to preserve schedule Test existing Ardustat
Need DUT – Chlorine Generator?
Current Status
Questions?