(Invited) triboelectric Nanogenerator Based Sensors for Water Quality Evaluation

Abstract

Clean water is a necessary component for all life. Unfortunately, in many countries, both developed and not, clean water is not a guarantee. Because of that, there has been a growing market for personal water quality sensors and tools. This ranges from electronic meters to determine pH and salinity, to reagent strips for heavy metals such as lead and mercury. Each of these methods has its strengths and weaknesses, and in our search for new technology to compete with this, have been investigating the principle of triboelectrification as one possibility. When objects of different work functions are placed in contact, there is a charge transfer that occurs. When hooked up to an external load, and cyclically contacted and released, this can be harnessed for power generation in the form of triboelectric nanogenerators (TENG) or nanosensors (TENS). While the technology began with contacting solid objects, it was soon discovered that the principle also applies to interactions between solids and liquids.We have begun investigations on constructing triboelectric sensors for detecting small amounts of contaminants in water. By chemically modifying a copper wire, we can detect concentrations of contaminants such as acetone at concentrations as low as 5% per volume, while avoiding false positives from similar compounds like ethanol. We were also able to measure ammonia in water at similar concentrations. The coating preferentially binds to the target molecule, changing the work function, which in turn changes the output voltage. A Dobot Magician robot arm is used to help produce more consistent and reproducible signals. In the future, we will continue pushing this technology to detect other common contaminants, while miniaturizing the robotics and computer systems for collecting and processing the data, respectively. Figure 1