Description:

Potentiostat systems measure across a 3 electrode electrochemical cell. The potentiostat must maintain constant voltages across its terminals while reading current from a third terminal and can determine characteristics and quantity of organic and inorganic compounds and ions using scanning techniques such as amperometry, cyclic voltammetry, differential pulse voltammetry, chronoamperometry or fast scan cyclic voltammetry [1,2]. In these techniques, the applied voltage across electrodes can be scanned, held constant, or pulsed. The output is then digitized and sent to a microprocessor to provide calibration and control before being transmitted wirelessly. The potentiostat performs amperometry and cyclic voltammetry with a range of -1V to 1V and a scan rate of 50 mV/s. Current levels in the range of pA to 100 µA can be detected depending on the chemical composition of the solution and the electrode material. The open source RISC based microprocessor can provide the calibration and control to the potentiostat. The RISC-V processor will be based on [6], which contains machine learning architecture, debugging (eg. JTAG and UART), and I2C. For wireless transmission the architecture is based on a direct conversion transceiver consisting of LNA, I/Q mixer, complex filters, VCO, and LO generators, and power amplifiers, and is directly inspired by  [5]. 

Figure 1: Circuit Schematic of the Analog Front-End 

Figure 2: Circuit block diagram of the Wireless Transceiver

Design goal: 

Among the many global social problems, water pollution is a prominent one directly affecting health outcomes.  Approximately 2221 different organic compounds have been found in global water bodies with 765 different ones being found in drinking water [4]. Serious health and environmental damage can occur due to the direct contact and/or ingestion of  water contaminated with heavy metals and pharmaceuticals [2,7]. Electrochemical measurements are routinely used to quantify and identify various chemical particles using benchtop instruments in the lab. Thus, the goal of this design project is to develop a low cost wireless potentiostat system suitable for water quality monitoring. Primary tasks are to design the potentiostat and the wireless transceiver.

Target performance summary:

References: 

[1] Simone Aiassa, José David González Martínez, Danilo Demarchi, Sandro Carrara, “New Measurement Method in Drug Sensing by Direct Total-Charge Detection in Voltammetry”, IEEE International Symposium on Medical Measurements and Applications, pp. 1-6, 2020.

[2] V. Bianchi, A. Boni, S. Fortunati, M. Giannetto, M. Careri and I. De Munari, “A Wi-Fi Cloud-Based Portable Potentiostat for Electrochemical Biosensors,” IEEE Transactions on Instrumentation and Measurement, vol. 69, no. 6, pp. 3232-3240, June 2020. 

[4] Tian Jinghuan and Wang Yi, “A novel water pollution monitoring approach based on 3s technique,”  International Conference on E-Health Networking Digital Ecosystems and Technologies, pp. 288-290, 2010.

[5] Chia-Jun Chang et al., “A CMOS transceiver with internal PA and digital pre-distortion for WLAN 802.11a/b/g/n Applications,” IEEE Radio Frequency Integrated Circuits Symposium,  pp. 435-438, 2010.

[6] https://github.com/Purdue-SoCET/AFTx06_Caravel.

[7] https://www.un.org/waterforlifedecade/quality.shtml 

Team Members:

Nicole Mcfarlane : Team Advisor
Associate Professor, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Andalib Nizam : Team Leader
Graduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Farin Rahman : Member
Graduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Colin Wikle : Member
Undergraduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Travis Graham : Member
Undergraduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Liza Barre : Member
Undergraduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.

Justin Cash : Member
Undergraduate Student, EECS Dept. The University of Tennessee, Knoxville TN, USA.