Tuesday, August 4, 2009
pHduino - An pHmeter using Arduino Board
pHduino is a open hardware and open software for pH measuments using a glass electrode sensor for hydrogen ion and a Arduino board.
Just after I returned from my last post-doc project at San Antonio, Texas, I decided not restart my last project. I did it to finish some works and make an open hardware project in electrochemistry. After some tests, a friend called Denis Vidal, suggested me to construct a pHmeter. I made the project in a weekend and I spent more three weekend to adjust the layout and documentation. I made this project just for fun.
This pHmeter can be powered by a power supply and display the data using a LCD. Also, you can control it and power it up by USB port. The offset and slope can be adjust manually by potentiometers or by an auto calibration code (not implemented, yet). There is a temperature sensor for temperature compensation.
It is inferior and a little bit more expensive from a portable low resolution pHmeter. However, it is interfaceable, programmable, expansible, and, the more important, open and free!
Again, it is not intent to be a high resolution analytical instrument to compete with a commercial pHmeter. It is different.
I am improving the hardware and the software. I need make some tests and some benchmarks. I will publish the electronic scheme, PCB layout, and the code as soon as possible. I will write a program to run in the computer (cross-plataform) to read, plot, and save the data. At the moment, I am using a serial terminal to display the data by USB port.
In a Chemistry Lab, the pHmeter is typically used to adjust pH of solutions and buffers. In Environment Chemistry we can use it for monitoring the water of rivers, sea, dams, reservoirs, rain, and etc. For a not technician end users, he can monitoring the pH of an aquarium. There are many other possible applications. It is very important to know the pH glass electrode sensor limitations to make the write use. It is possible substitute the pH electrode by a different ion-selective electrode.
This project was possible by the idea from my friend Denis, the space that my supervisor gave me, prof. Dr. Emanuel Carrilho, BioMicS Group, Institute of Chemistry from São Carlos, University of São Paulo and by facilities and suggestions from prof. Dr. Claudimir Lucio do Lago, LAIA Laboratory, Institute of Chemistry of University of São Paulo. I would like to thank Fapesp - Fundação de Amparo à Pesquisa do Estado de São Paulo by the financial support for my different projects during my academic life.