3D printing of conductive elastomers is a promising route to personalized health monitoring applications due to its flexibility and biocompatibility. Here, a one‐part, highly conductive, flexible, stretchable, 3D printable carbon nanotube (CNT)‐silicone composite is developed and thoroughly characterized. The one‐part nature of the inks: i) enables printing without prior mixing and cures under ambient conditions; ii) allows direct dispensing at ≈100 µm resolution printability on nonpolar and polar substrates; iii) forms both self‐supporting and high‐aspect‐ratio structures, key aspects in additive biomanufacturing that eliminate the need for sacrificial layers; and iv) lends efficient, reproducible, and highly sensitive responses to various tensile and compressive stimuli. The high electrical and thermal conductivity of the CNT‐silicone composite is further extended to facilitate use as a flexible and stretchable heating element, with applications in body temperature regulation, water distillation, and dual temperature sensing and Joule heating. Overall, the facile fabrication of this composite points to excellent synergy with direct ink writing and can be used to prepare patient‐specific wearable electronics for motion detection and cardiac and respiratory monitoring devices and toward advanced personal health tracking and bionic skin applications.

3D Printing In article number 2202204, Daeha Joung and co‐workers present a 3D printed magnet‐infused origami platform for 3D cell culture assessments. The platform enables spatiotemporal control of 3D cell activities and planar and vertical proliferation of cells in microchannels. This system can propel higher‐order control in capturing cell culture conditions at an appropriate scale.

3D printed platforms have diverse possible applications in cell‐based assays, creating biomimetic tissue or organ microenvironments, delineating cell‐to‐cell, cell‐to‐matrix, or cell‐to‐local microenvironment interactions, and investigating drug discovery. Existing engineering techniques limit physiologically relevant 3D cell proliferation and spatiotemporal organization of cells. Herein, a facile fabrication strategy is proposed for magnetically controllable, shape‐morphing, superparamagnetic 3D iron oxide nanoparticle/cellulose acetate scaffolds produced via origami‐inspired 3D printing technology. The additional dimensionality allows the creation of highly customizable 3D in vitro magnetoactive cell culture platforms in which cells can experience gravity with uniform surface morphology, favorable long‐term biodegradability, and low iron ion release that can be actuated numerous times. Leveraging this platform's properties, the spatial and temporal proliferation of Saccharomyces cerevisiae cells are demonstrated, enabling pre‐ and post‐folding dynamic regulation of cellular behaviors at a local level. It is further demonstrated that the viability of the seeded NIH/3T3 fibroblasts remains > 94% and spreads and proliferates within the scaffold channels over a period of 7 d in culture. Therefore, this transformative cell culture assessment could provide alternative directions to revolutionize the 3D cell culture platform to monitor cellular responses to drugs, compounds, and external stimuli and advance personalized treatments.

Bio‐inspired cilium‐based mechanosensors offer a high level of responsiveness, making them suitable for a wide range of industrial, environmental, and biomedical applications. Despite great promise, the development of sensors with multifunctionality, scalability, customizability, and sensing linearity presents challenges due to the complex sensing mechanisms and fabrication methods involved. To this end, high‐aspect‐ratio polycaprolactone/graphene cilia structures with high conductivity, and facile fabrication are employed to address these challenges. For these 3D‐printed structures, an “inter‐cilium contact” sensing mechanism that enables the sensor to function akin to an on‐off switch, significantly enhancing sensitivity and reducing ambiguity in detection, is proposed. The cilia structures exhibit high levels of customizability, including thickness, height, spacing, and arrangement, while maintaining mechanical robustness. The simplicity of the sensor design enables highly sensitive detection in diverse applications, encompassing airflow and water flow monitoring, braille detection, and debris recognition. Overall, the unique conductive cilia‐based sensing mechanism that is proposed brings several advantages, advancing the development of multi‐sensing capabilities and flexible electronic skin applications in smart robotics and human prosthetics.