Hydrogel-based intelligent greenhouse films for simultaneous fogging prevention and indoor environmental monitoring

Fogging prevention and environmental monitoring in a greenhouse are usually accomplished by different components, as the former relies on persistent surface-wetting capability, while the latter requires conductivity or capacitance to vary with ambient conditions. Combining these seemingly unrelated functions presents a significant challenge. Here, we report an all-in-one hydrogel that integrates these exclusive functions, enabling it to simultaneously work as an anti-fogging coating and environmental monitor in greenhouses. The strategy involves constructing loosely crosslinked hydrophilic networks enriched with abundant free ions and a specific amount of glycerol. The transparent hydrogel, composed of long-chain polymers, exhibits excellent adhesion to the inner surface of the greenhouse film and significantly decreases its water contact angle by filmwise condensation, thereby reinforcing the anti-fogging properties of the film without sacrificing its transparency. Meanwhile, the presence of glycerol and free ions enables the gel to sustain a wide range of temperature and humidity while displaying environmentally sensitive conductivity, endowing the gel with the same function as conventional rigid environmental sensors. As a proof-of-concept demonstration, a wireless indoor environmental monitoring system in a homemade lean-to greenhouse is established by utilizing hydrogel as the sensing module, which also performs well in prohibiting fogging on the greenhouse film. We hope this work could provide some inspiration for the development of multifunctional intelligent greenhouse films.