Experiment Hardware
For hardware design, based on previous studies[1, 5], we build a microcontroller based potentiostat to perform cyclic voltammetry method. The script presented in the Appendix was used to automatically perform cyclic voltammetry experiments at different scan rates as seen in the diffusion coefficient determination section of the main manuscript. All the parameters (scan rates and potential window) can be defined in the software named Paqari Lab. This shows the flexibility and versatility of the design (both hardware and software) in allowing to perform multiple experiments and automating repetitive procedures.
Figure 1: schematic design of the Arduino-based potentiostat (pin connections board without the Arduino).
Figure 2: Arduino Nano and Bluetooth module indicating output pins of signals to the potentiostat (red arrows), and input pin from the obtained signals and the electrochemical cell (blue arrow).
Figure 3: Schematic design of our sensor. The box containing the potentiostat circuit was printed using 3D printing techniques.
We use a free access application for the control of Paqari Stat. This mobile application was built in the MIT App Inventor 2 platform (http://ai2.appinventor.mit.edu/), and it allows the input of the electrochemical parameters used during the experiments. We have also included a real-time display of the obtained data, which can also be exported in a .csv format to facilitate its graphing in the same smartphone. The detection limit of our Arduino-based detection system has to be further verified in the future study, therefore most of the cyclic voltammetry measurement our experiment was conducted using the commercial electrochemical workstation made by Shang Hai CH Instruments.
Figure4 User surface of Paqari Lab
Figure4 User surface of Paqari Lab
Reference
1. Meloni, G.N., Building a Microcontroller Based Potentiostat: A Inexpensive and Versatile Platform for Teaching Electrochemistry and Instrumentation. Journal of Chemical Education, 2016. 93(7): p. 1320-1322.
2. Cordova-Huaman, A.V., V.R. Jauja-Ccana, and A. La Rosa-Toro, Low-cost smartphone-controlled potentiostat based on Arduino for teaching electrochemistry fundamentals and applications. Heliyon, 2021. 7(2): p. e06259.