Simple, low-cost, and high-performance atmospheric water harvesting (AWH) still remains challenging in the context of global water shortage. Here, we present a simple and low-cost macroporous hydrogel for high-performance AWH to address this challenge. We employed an innovative strategy of pore foaming and vacuum drying to rationally fabricate a macroporous hydrogel. The hydrogel is endowed with a macroporous structure and a high specific surface area, enabling sufficient contact of the inner sorbent with outside air and high-performance AWH. The experiments demonstrate that macroporous hydrogels can achieve high-performance AWH with a broad range of sorption humidity [relative humidity (RH) from 100% to even lower than 20%], high water sorption capacity (highest 433.72% of hydrogel’s own weight at ∼98% RH, 25 °C within 60 h), rapid vapor capturing (the sorption efficiency is as high as 0.32 g g–1 h–1 in the first 3 h at 90% RH, 25 °C), unique durability, low desorption temperature (∼50 °C, lowest), and high water-releasing rate (release 99.38% of the sorbed water under 500 W m–2 light for 6 h). The results show that this macroporous hydrogel can sorb water more than 193.46% of its own weight overnight (13 h) at a RH of ∼90%, 25 °C and release as high as 99.38% of the sorbed water via the photothermal effect. It is estimated that the daily water yield can reach up to approximately 2.56 kg kg–1 day–1 in real outdoor conditions, enabling daily minimum water consumption of an adult. Our simple, affordable, and easy-to-scale-up macroporous hydrogel can not only unleash the unlimited possibilities for large-scale and high-performance AWH but also offer promising opportunities for functional materials, soft matter, flexible electronics, tissue engineering, and biomedical applications.

A hydrogel strain sensor can successfully transform its deformation into resistance changes, offering novel options for the Internet of Things (IoT) and artificial intelligence (AI). However, it remains challenging to prepare hydrogel sensors with superior performance (e.g., high conductivity). Here, we produced a conductive hydrogel (named PPC hydrogel) utilizing only three components, PVA (poly(vinyl alcohol)), PAAS (polyacrylate sodium), and CaCl 2 , through freezing cross-linking and ion chelation. The PPC hydrogel is endowed with high electrical conductivity of approximately 5.2 S/m without the addition of highly conductive materials due to the unique ionic cluster mesh structure, thus enabling an outstanding performance of strain sensing. The PPC hydrogel also maintains electrical conductivity in frozen and underwater conditions and resists swelling in underwater environments, allowing it to be used under water for extended periods of time (more than 15 days). The PPC hydrogel-based strain sensor can be used as a flexible electrode for electrocardiogram (ECG) and electromyogram (EMG) examinations and sensitively monitor human activity as well as recognize handwriting. Moreover, we designed a python-based visualization program combined with a PPC hydrogel array to implement pressure-sensing digital image mapping for remote IoT monitoring. As a flexible sensor for biosafety, the PPC hydrogel has potential applications in the field of intelligent sensing, the IoT, and even Internet of Body systems.

The preparation of smart sensors with multiple sensory systems, reusable property, and high sensitivity remains a challenge. Here, inspired by a sponge, we develop a multisensory PCA–poly(vinyl alcohol) (PVA)/borax–LiCl hydrogel (named PPL hydrogel) with low cost and simple fabrication process using sodium polyacrylate (PAAS), PVA, and lithium chloride (LiCl) to address this challenge. PPL hydrogel has a sponge‐like porous structure and can repeatedly “absorb” and “drain” water, while maintaining good tensile (strain up to 1442%) and electrical conductivity. PAAS builds the main skeleton of PPL hydrogels and provides the basis for building the pore structure, PVA enhances the mechanical properties of the crosslinked network, while LiCl ionic solution further improves the conductivity, which can reach 8.8 s m−1 and be increased nearly 42 times better than without LiCl. Therefore, this makes PPL hydrogel a very sensitive sensing system for wearable devices that can be used to detect signals from the human body. Additionally, PPL hydrogel is also capable of detecting temperature due to its temperature‐sensitive properties. Moreover, PPL hydrogel can also roughly identify the basic properties of different solvents. Our simple, low‐cost and multisensory PPL hydrogel offers promising opportunities for multisensory sensors, even functional/smart materials, flexible/wearable devices, and medical care.