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Potentiostat

Team Members: Kyle Bloomer Josh Geiman Lucas Bennett. Potentiostat. Team Sponsor: Dr. Cindy Harnett. Harnett Lab. Dr. Harnett's laboratory needs 15 potentiostats for her microfluidics lab

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Potentiostat

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  1. Team Members: Kyle Bloomer Josh Geiman Lucas Bennett Potentiostat Team Sponsor: • Dr. Cindy Harnett

  2. Harnett Lab • 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

  3. What is a Potentiostat? • A Potentiostat is an instrument that is used to characterize electrochemical reactions • Fuel cells – reacts liquid fuel and oxidizer to produce electricity • Gas generators – Uses electrolysis to generate gas • A potentiostat measures the voltage difference between a Working Electrode and a Reference Electrode • Three electrode configuration • Most commercial potentiostats provide a second mode of operation that measures the current flow between the Working and Counter Electrodes • This mode is known as a “galvanostat”

  4. History - Ardustat • 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

  5. Ardustat Hardware

  6. Ardustat GUI – Connect & Setup

  7. Ardustat GUI – Data Logging

  8. Ardustat Code Example • Show pictures of GUI or firmware code • Before Ben • After Ben

  9. Previous Project Diagram

  10. Previous Project Test Set

  11. Current Status • 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

  12. Research • 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

  13. Cheapstat Features • 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 • List the modes here

  14. Cheapstat Hardware Front Panel PCB Assembly JoyStick To Cell Electrodes

  15. 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

  16. Design Goals - Software • 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

  17. Project Goals - Other • Characterize electrical performance for a typical electrochemical device • Compare electrical measurements with the existing Ardustat • Two electrode vs. three electrode measurement differences

  18. System Diagram

  19. Major Components • Processor • Firmware • Display/Data Management System (DDMS) • GUI software • Power supply

  20. System Diagram

  21. 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

  22. System Diagram

  23. DDMS Requirements • 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

  24. System Diagram

  25. Voltage Converter • Three options are available: • Wall Wart • USB • Battery power • Microprocessor requires 5 VDC • Estimated 3 watts

  26. Current Status • Build and test Cheapstat using current design • CheapStatParts have been ordered • Research ongoing regarding firmware development environment • Software development kit to preserve schedule • Test existing Ardustat • Need DUT – Chlorine Generator?

  27. Questions?

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