Imagine walking past a "crying wall" — a wall dripping with condensation from Hong Kong's summer humidity — and realizing that this nuisance could actually generate electricity. This project invites students to explore a hyper-local energy solution using water-absorbing polymers that thrive in exactly the kind of wet environment Hong Kong endures for half the year. Instead of fighting the moisture, we propose to harvest it by converting it into tiny electrical signals. In this hands-on project, you will prepare simple hydrogels, fabricate devices and measure its generated power. The goal is not to replace the power grid but to develop a low-cost, maintenance-free energy source to power small sensors, air quality monitors, or LED indicators that could be stuck directly onto damp walls. No prior experience needed—just curiosity about turning a local annoyance into an opportunity. By the end of the project, you will have built a prototype humidity-powered device and gained skills in materials science, electrochemistry, and sustainable design, all while solving a problem that every Hongkonger knows too well.