Cultivated meat and fish require two bioprocessing stages to reach commercial viability: expansion of cells to sufficient numbers, and structuring of those cells into a product which reproduces the architecture and texture of conventional meat. Microcarriers and 3D printing are the principal technologies addressing these stages, and both must operate under constraints which do not apply in biomedical practice, because the resulting materials are consumed rather than discarded. This review examines how microcarriers and 3D-printed constructs for cultivated meat and fish have been fabricated, organized according to production method. For microcarriers, we cover emulsification, electrospraying, dripping, decellularization, biofabrication, surface topography engineering, and the use of commercially available carriers. For 3D printing, we cover extrusion bioprinting, extrusion into a support bath, acellular printing with post-print cell seeding, vat photopolymerization, electrohydrodynamic printing, and screen printing. For each method, we describe its principle, advantages, limitations, and the process parameters, together with representative studies and the expansion or printing performance reported in them. Although some proof-of-concept platforms still utilize non-food-grade materials, transitioning to edible biopolymers is essential for both technologies. In addition, these approaches have started to overlap, as cell-laden microcarriers serve as potential building blocks for printed constructs. Designing both systems together, rather than in isolation, will therefore be crucial for producing structured cultivated meat and fish at scale.
Hydrodynamic interactions (HIs) are fundamental to both microstructural dynamics and macroscopic rheology in colloidal suspensions. Quantifying many-body and time-dependent HIs directly at the particle-pair level, however, remains an experimental challenge. This review examines the capabilities and physical limitations of established experimental approaches, including bulk rheometry, passive microrheology, and active microrheology. It then focuses on a recent rotation-based optical tweezer methodology that exploits the translation-rotation hydrodynamic coupling of an isotropic sphere. Because such a probe experiences no net optical torque, its rotation is not attenuated by the trapping potential. This approach provides sufficient sensitivity to resolve long-range and many-body HIs in Newtonian media, as well as time-dependent HIs arising from the structural memory of viscoelastic media. Constraints associated with optical transparency, the accessible viscosity range, and statistical throughput define its domain of applicability, so that the method complements rather than replaces the established techniques. The review concludes by discussing prospects for probing mesoscale heterogeneity in complex fluids and for extending the approach to biological and nonequilibrium systems.
Hydrogels combine high water content with tunable mechanical, interfacial, rheological, and transport properties, supporting their use in wound management, surgical adhesion and sealing, controlled drug delivery, and cosmetic and topical formulations. This review examines how these coupled properties govern hydrogel performance across different biomedical and topical applications, with rheology providing a framework for linking network structure and time-dependent mechanical behavior to handling, tissue contact, and functional stability. Across these applications, material design requires coordinated control of processability, conformability, interfacial retention, molecular transport, and functional lifetime. Changes in crosslinking, reversible interactions, swelling, and degradation can improve one function while altering others, emphasizing the need to evaluate hydrogel properties as an interdependent system rather than as isolated parameters. Rheological measurements can help characterize these relationships when interpreted together with adhesion, transport, degradation, and biological performance. The resulting design principles emphasize maintaining an application-specific combination of properties throughout the intended period of use. Future progress will require standardized and application-relevant testing under physiologically relevant fluid exposure and mechanical loading, together with reproducible performance after processing, storage, and sterilization where required. Establishing quantitative relationships among composition, rheological behavior, and functional outcomes may further support more systematic formulation design and translation.
Among various electrolyte systems, solid polymer electrolytes (SPEs) have attracted significant attention because they enhance the safety and enable flexible cell design. However, because SPEs suffer from low ionic conductivity and insufficient interfacial stability, additives are essential to address these problems. In this work, cellulose nanocrystals (CNCs) were introduced as an alternative filler in poly(ethylene oxide) (PEO)-based electrolytes. Due to their rod-like geometry, their high surface area, hydrophilicity, and good compatibility with the polymer matrix, CNCs enable uniform dispersion and enhance interfacial interactions. Rheological, mechanical, and electrochemical analyses were conducted to evaluate solution stability, film integrity, and ionic transport. This study investigates how CNCs govern the structural and electrochemical attributes of SPEs, aiming to simultaneously enhance both cell performance and manufacturability for next-generation all-solid-state batteries (ASSBs).
