Ultrathin Nanogold Films Enable Self-Powered Sensors and Smart Wearables

Researchers have developed an ultrathin flexible film embedded with nanoscale gold particles that can efficiently convert tiny temperature changes into electrical signals — a breakthrough that could enable self-powered sensors, wearable electronics, smart photodetectors, low-grade heat harvesters, and next-generation energy-efficient devices for healthcare and environmental monitoring.

As demand rises for lightweight, flexible, and low-power materials capable of harvesting ambient thermal energy, scientists are increasingly exploring hybrid systems that combine plasmonic materials with pyroelectric polymers. While earlier plasmonic-pyroelectric and PVDF-based composite systems improved thermal-to-electrical conversion, many depended on micron-thick structures or poorly controlled interfaces, limiting their use in compact, wearable technologies.

Addressing these challenges, researchers from the Institute of Nano Science and Technology (INST), an autonomous institute under the Department of Science and Technology, demonstrated that incorporating a tiny amount of nanogold into polyvinylidene fluoride (PVDF) — a widely used ferroelectric polymer — significantly enhances its pyroelectric performance, or its ability to generate electricity from temperature fluctuations.

The research team, led by Dipankar Mandal along with collaborators including Sudip Naskar, engineered ultrathin PVDF films less than 100 nanometres thick containing hexagonal nanogold particles. Their approach focused on understanding how nanoscale gold-polymer interactions, dipole alignment, and confined plasmonic excitations influence pyroelectric behaviour in ultrathin films.

The researchers found that embedding hexagonal nanogold particles created a nearly pure polar phase in the PVDF matrix with highly ordered dipoles — a key requirement for efficient pyroelectric energy conversion. The study further revealed that a metastable hexagonal close-packed gold nanoparticle phase could be integrated into a robust two-dimensional hybrid thin film, where plasmon-dipole-electron coupling worked cooperatively to improve pyroelectricity, dipole ordering, and broadband optical absorption.

Published in Advanced Functional Materials, the study demonstrated efficient pyroelectric energy conversion within a narrow ambient temperature range of 294–301 K. The findings represent an important advance toward self-powered thermal sensing and wearable energy-harvesting technologies designed to operate under everyday environmental conditions.