Peiwen Liu

The advancement of smart agriculture is becoming increasingly dependent on sensor technologies that enable the digitization and optimization of agricultural processes. Traditional sensors, however, are constrained by their inherent rigidity, poor conformability to irregular surfaces, and limited adaptability to harsh agricultural environments. Flexible sensors, particularly those made from polymer‐based materials, offer substantial advantages due to their lightweight, flexible, and highly sensitive properties. These sensors are key to the performance, stability, and environmental resilience required for sustainable smart agriculture applications. This review provides a comprehensive overview of polymer‐based flexible sensors, focusing on the types of polymer substrates, interface engineering methods, and their applications in agriculture. We discuss how these sensors address agricultural challenges, including their integration with machine learning (ML) to improve data analysis and decision‐making. The review also highlights the ongoing challenges and future opportunities for enhancing the performance of these sensors, including material stability, interface optimization, and large‐scale implementation. Ultimately, this work aims to provide valuable insights and technical guidance for researchers and engineers developing high‐performance, sustainable flexible sensors to advance the frontiers of smart agriculture.

Conventional polyolefin battery separators are limited by inherent deficiencies in thermal stability, electrolyte wettability, and environmental sustainability, which collectively hinder the advancement of high-energy-density energy storage systems. In this context, biomass macromolecular materials, including cellulose, chitin/chitosan, and lignin, have emerged as promising candidates for next-generation separators owing to their environmental benefits, exceptional hydrophilicity, and superior thermal resistance. This review systematically evaluates the molecular characteristics of these three biomass systems, alongside core gel-state processing and network-forming processes such as electrospinning, solution casting, nonwoven technology, and hydrogel-assisted film formation. It further highlights their cutting-edge applications in lithium-ion, lithium–sulfur, zinc-ion, and solid-state batteries, emphasizing their behavior as polymer gel electrolytes and gel-derived structural matrices. To overcome key challenges associated with mechanical robustness, interfacial compatibility, and network uniformity, advanced modification strategies are critically discussed, including surface chemical functionalization, multicomponent hybrid composite formulation, and rational three-dimensional structural engineering. Overall, current research evidence demonstrates that rationally designed biomass-based gel networks and membranes can effectively suppress metal dendrite growth, immobilize soluble polysulfide intermediates via supramolecular interactions, and reduce interfacial impedance in solid-state systems, thereby offering a viable pathway toward safer, more sustainable, and commercially competitive high-energy-density batteries.

Hydrogel‐based solar evaporators have garnered attention in solar‐powered interfacial evaporation for clean water due to their hydrophilicity, porous structure, and large surface area. However, achieving high evaporation rates, robust mechanical properties, and antibacterial performance remains challenging. In this study, we successfully construct a composite hydrogel solar evaporator with excellent comprehensive performance. Cerium dioxide (CeO ₂ ) nanoparticles with antibacterial properties are synthesized in situ using chitin nanocrystals (ChNC) as bio‐based reinforcing nanofillers. These components are integrated with polypyrrole (PPy) as a photothermal absorber and poly(vinyl alcohol) (PVA) as the structural backbone. The nanocomposite hydrogel evaporator is prepared via a freeze‐thaw cycling method. The 15%‐ChNC/CeO ₂ /PPy/PVA (15%‐CCPP) nanocomposite hydrogel exhibits superior compressive strength, achieving 62.4 kPa at a 60% compression rate, 2.25 times higher than pure PVA hydrogel. In addition, the 15%‐CCPP hydrogel demonstrates significant antibacterial activity. Meanwhile, the nanocomposite hydrogel achieves a high evaporation rate of up to 2.65 kg·m ⁻² ·h ⁻¹ under 1 Sun (1.0 kW·m ⁻² ) irradiation. The combination of excellent mechanical properties, antibacterial performance, and high evaporation efficiency highlights the potential of this nanocomposite hydrogel evaporator for application in the solar‐powered water purification systems.

It is a longstanding challenge to aptly describe the natural assembly process of chitin Bouligand organization as well as biomimetic construct these position-dependent structures with the isolated chitin nanodomains. Here, we report a fixed-boundary evaporation-induced self-assembly (FB-EISA) modality using chitin nanocrystals (ChNCs) in the capillaries, where the generation of continuous and ordered anisotropic phase relies on the growth of phase boundary towards the opposite direction of water evaporation. Distinct from the previous EISA modalities with the moving evaporation interface, the pinned air-liquid interface at the end of capillaries in a confined environment acts as the evaporation interface and initial deposition site of ChNCs simultaneously. During the whole self-assembly process via successive evaporation, the generation of droplets-like ChNCs clusters known as tactoids is suppressed. Therefore, continuous birefringent multi-layers as nested multiple paraboloid structures of ChNCs with a density gradient are gradually generated, before cylindrical tubes are formed finally. The FB-EISA process can be accelerated by heat and maintains stable regardless of vibration or different capillary opening directions relative to gravity direction. This FB-EISA modality in confined geometry allows rapid formation of ChNCs-based photonics-quality structure of larger length scales and enables us to deepen our understanding of the natural self-assembly process in diverse biological species.

Periodate oxidation reaction occurring directly on chitin has been neglected in polysaccharide chemistry so far. Herein, we present the first direct alkaline periodate oxidation of chitin, which demonstrates at the same time a novel approach for the preparation of chitin nanocrystals (ChNCs). This oxidation is based on an unprecedented selective reaction of non-ordered domains of chitin by the dimeric orthoperiodate ions (H₂I₂O₁₀ ⁴⁻) as the major species in alkaline surroundings. Nearly 50 wt% of non-ordered regions are dissolved after sequential accelerated partial deacetylation, periodate oxidation and β-alkoxy fragmentation, which allows the isolation of up to 50 wt% of uniform anisotropic zwitterionic ChNCs.

This Minireview focuses on the selective isolation methods for the preparation of cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs). Various selective preparation strategies with specific preparation conditions and reaction mechanisms are summarized. In particular, these selective reaction routes include controlled acid hydrolysis and selective oxidations at specific positions of cellulose or chitin fibers as well as particular reaction sites of the repeating monosaccharide building blocks of their main chains. These lead to selective cleavage of the ordered and non‐ordered regions of cellulose and chitin and result in efficient production of CNCs and ChNCs.

Biodegradable nanoparticles (NPs) have shown great promise as intracellular imaging probes, nanocarriers and drug delivery vehicles. In this study, we designed and prepared amphiphilic cellulose derivatives via Schiff base reactions between 2,3-dialdehyde cellulose (DAC) and amino compounds. Polymeric NPs were facilely fabricated via the self-assembly of the as-synthesized amphiphilic macromolecules. The size distribution of the obtained NPs can be tuned by changing the amount and length of the grafted hydrophobic side-chains. Anticancer drugs (DOX) were encapsulated in the NPs and the drug-loaded NPs based on cellulose derivatives were stable in neutral and alkaline environments for at least a month. They rapidly decomposed with the efficient release of the drug in acidic tumor microenvironments. These drug-loaded NPs have the potential for application in cancer treatment.

Reported here for the first time is the alkaline periodate oxidation of lignocelluloses for the selective isolation of cellulose nanocrystals (CNCs). With the high concentrations as a potassium salt at pH 10, periodate ions predominantly exist as dimeric orthoperiodate ions (H₂I₂O₁₀⁴⁻). With reduced oxidizing activity in alkaline solutions, dimeric orthoperiodate ions preferentially oxidized non‐ordered cellulose regions. The alkaline surroundings promoted the degradation of these oxidized cellulose chains by β‐alkoxy fragmentation and generated CNCs. The obtained CNCs were uniform in size and generally contained carboxy groups. Furthermore, the reaction solution could be reused after regeneration of the periodate with ozone gas. This method allows direct production of CNCs from diverse sources, in particular lignocellulosic raw materials including sawdust (European beech and Scots pine), flax, and kenaf, in addition to microcrystalline cellulose and pulp.