Electroactive polymers (EAPs) represent a versatile class of smart materials capable of converting electrical stimuli into mechanical motion and vice versa, positioning them as key components in the next generation of actuators and sensors. This review summarizes recent developments in both electronic and ionic EAPs, highlighting their activation mechanisms, material architectures, and multifunctional capabilities. Representative systems include dielectric elastomers, ferroelectric and conducting polymers, liquid crystal elastomers, and ionic gels. Advances in fabrication methods, such as additive manufacturing, nanocomposite engineering, and patternable electrode deposition, are discussed with emphasis on miniaturization, stretchability, and integration into soft systems. Applications span biomedical devices, wearable electronics, soft robotics, and environmental monitoring, with growing interest in platforms that combine actuation and sensing within a single structure. Finally, the review addresses critical challenges such as long-term material stability and scalability, and outlines future directions toward self-powered, AI-integrated, and sustainable EAP technologies.

The present work demonstrates the manufacturing process of a pneumatic bellow actuator with an embedded sensor, utilizing a novel manufacturing approach through the complete use of additive manufacturing techniques, such as direct ink writing (DIW) and traditional fused deposition modeling (FDM) methods. This study is innovative in its integration of a dielectric electroactive polymer (DEAP) structure with sensing electrodes made of conductive carbon grease (CCG), showcasing a unique application of a 3D-printed DEAP with CCG electrodes for combined DEAP sensing and pneumatic actuation. Initial experiments, supported by computational simulations, evaluated the distinct functionality of the DEAP sensor by itself under various pressure conditions. The findings revealed a significant change in capacitance with applied pressure, validating the sensor’s performance. After sensor validation, an additive manufacturing process for embedding the DEAP structure into a soft pneumatic actuator was created, exhibiting the system’s capability for dual sensing and actuation, as the embedded sensor effectively responded to applied actuation pressure. This dual functionality represents an advancement in soft actuators, especially in applications that require integrated and responsive actuation and sensing capabilities. This work also represents a preliminary step in the development of a 3D-printed dual-modality actuator (pneumatic and electrically activated DEAP) with embedded sensing.

Additive manufacturing (AM) has expanded the design space for actuator systems by enabling complex internal geometries, multimaterial architectures, functional gradients, embedded channels, and application-specific components that are difficult to realize using conventional fabrication alone. These capabilities are particularly relevant when actuator performance is governed by the coupling between material selection, printed architecture, stimulus response, and system-level integration. This review examines additively manufactured actuators and actuator components using a material-architecture-function-integration framework. The actuator classes considered include soft pneumatic and fluidic actuators, electroactive and piezoelectric polymer actuators, shape-memory and 4D-printed actuators, magnetic and magnetoactive actuators, and printed pneumatic, hydraulic, mechanical, and aerospace-grade actuator components. Representative applications are discussed across biomedical and rehabilitation systems, aerospace and deployable mechanisms, soft robotics, and industrial automation. Beyond summarizing printed actuator demonstrations, the review analyzes the integration barriers that determine whether AM actuators can transition from laboratory prototypes to functional systems. These barriers include material durability, leakage, fatigue, dielectric breakdown, filler dispersion, interfacial failure, dimensional variability, environmental sensitivity, auxiliary hardware requirements, sensing, control, and benchmarking. By organizing recent developments across actuator classes, application domains, and integration strategies, this review clarifies where AM provides a functional advantage over conventional fabrication and where further validation is required for reliable deployment.

A tightly regulated inflammatory response occurs during and following parturition; however, excessive or prolonged inflammation negatively affects herd health and productivity. The gut microbiota plays an important role in host immunity and metabolism and undergoes substantial changes during the transition period. However, the relationship between systemic inflammation, measured by serum acute-phase proteins, and gut microbial dynamics during early lactation remains poorly understood. We investigated fecal microbiota dynamics in relation to systemic inflammation in early postpartum dairy cows. Fecal and blood samples were collected from 71 Holstein cows on days 1 and 3 in milk (DIM). The V3-V4 region of the 16S rRNA gene was sequenced and microbial diversity, differential abundance, and microbial interaction networks were evaluated. Inflammatory status, defined by fibrinogen, haptoglobin, and their combined classification, was associated with significant alterations in fecal microbial composition during the immediate postpartum period, independent of body condition score, parity, DIM, and DNA extraction parameters. Differential abundance analyses revealed extensive taxonomic restructuring, while network analyses identified increased modularity, altered keystone taxa distribution, and greater compartmentalization of microbial interactions in animals with elevated inflammatory markers. Several taxa were consistently associated with inflammatory status across analytical approaches. Notably, Ruminococcaceae UCG-002 and Dielma were associated with inflammatory states, whereas Xylanibacter, Marvinbryantia, Akkermansia, and Oscillibacter were associated with non-inflammatory status. This study identifies an association between systemic inflammation and fecal microbiota composition in early transition dairy cows, providing a foundation for future microbiome-based biomarkers of inflammatory status.