Clean water is essential for life, but ensuring water quality remains a challenge in remote or heavily polluted areas. Now, researchers at National Taiwan University have developed a breakthrough technology—a compact, battery-free water quality monitoring system that operates using the natural motion of waves to detect contaminants in water.

This innovation integrates two core components. The first is a rotating triboelectric nanogenerator (R-TENG) that captures energy from water movement and converts it into electricity. The harvested energy powers a high-sensitivity transistor sensor based on AlGaN/GaN materials, renowned for its stability and performance in harsh environments. The related research has been published in the journal Nano Energy.

The sensor can detect a wide range of harmful substances with astonishing precision, including heavy metals (such as lead, arsenic, and chromium), pesticides, and microplastic particles.

The device is housed in a waterproof acrylic shell and driven by magnets, enabling continuous operation underwater while producing stable voltage even in high-humidity conditions. It takes approximately 10 seconds to charge a small capacitor, after which it supplies the energy required for real-time sensor measurements.

In both laboratory and river tests, the system performed reliably, distinguishing contaminants at levels as low as nanomolar concentrations and exhibiting a strong linear response to changes in water pH.

Most importantly, this self-powered sensor requires no batteries or power cables—factors that often hinder long-term environmental monitoring. By harvesting wave energy, it enables sustainable, long-term deployment in oceans, rivers, and lakes, contributing to ecological protection and public health.

Professor Tsung-Hung Lin stated: "This compact, self-powered device provides an intelligent solution for remote water quality monitoring and early pollution detection."