Date of Award

6-8-2016

Document Type

Thesis - SCU Access Only

Publisher

Santa Clara : Santa Clara University, 2016.

Department

Bioengineering

First Advisor

Unyoung Kim

Abstract

As the world population rises, there is an increase in agricultural production, which has compromised safe water consumption for many demographics. Phosphate, a compound commonly used in agriculture fertilizers, leaks into local water sources contaminating the resource for its consumers1. Since high levels of phosphate lead to osteoporosis, kidney damage and digestive issues in humans as well as eutrophication and destruction of natural ecosystems, the Environmental Protection Agency in the United States has limited phosphate levels to 25 parts per billion in lakes and reservoirs2,3. To combat the issue of phosphate contamination, widespread testing is necessary in affected areas, however current testing methods are expensive, off-site and time consuming. Since affected areas mainly comprise of developing nations, there is a need for an affordable and user-friendly phosphate testing platform. With our research, we present an affordable, rapid, user-friendly, and sensitive electrochemical phosphate sensor that has the ability to test water samples and provide immediate nutrient diagnosis.

The electrochemical sensor is composed of a three-electrode system and utilizes voltammetry for the detection of phosphate. The working, counter and reference electrodes are printed in carbon, platinum, and silver ink respectively onto a glass substrate. The sensor is then connected to an electrochemical analyzer which will apply voltammetry with a voltage range from 0.6 V to -0.3 V and a voltage scan rate of 1 V/s. Current peaks are then analyzed and correspond to the concentration of phosphate in the tested solution. From test experiments with our sensor, phosphate concentrations as low as 10 parts per billion are detectable.

The sensor will combine with a hand-held portable potentiostat and a mobile application to enhance the user-friendliness, speed, and affordability of phosphate detection in water. Our device has the ability to accurately test phosphate concentration in water samples and effectively communicate the results to its users. This rapid detection system contributes to improved water sanitation and global health.

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