Abstract Introduction Mechanical forces provide critical biological signals to cells. Within the distal lung, tensile forces act across the basement membrane and epithelial cells atop. Stretching ...devices have supported studies of mechanical forces in distal lung epithelium to gain mechanistic insights into pulmonary diseases. However, the integration of curvature into devices applying mechanical forces onto lung epithelial cell monolayers has remained challenging. To address this, we developed a hammock-shaped platform that offers desired curvature and mechanical forces to lung epithelial monolayers. Methods We developed hammocks using polyethylene terephthalate (PET)-based membranes and magnetic-particle modified silicone elastomer films within a 48-well plate that mimic the alveolar curvature and tensile forces during breathing. These hammocks were engineered and characterized for mechanical and cell-adhesive properties to facilitate cell culture. Using human small airway epithelial cells (SAECs), we measured monolayer formation and mechanosensing using F-Actin staining and immunofluorescence for cytokeratin to visualize intermediate filaments. Results We demonstrate a multi-functional design that facilitates a range of curvatures along with the incorporation of magnetic elements for dynamic actuation to induce mechanical forces. Using this system, we then showed that SAECs remain viable, proliferate, and form an epithelial cell monolayer across the entire hammock. By further applying mechanical stimulation via magnetic actuation, we observed an increase in proliferation and strengthening of the cytoskeleton, suggesting an increase in mechanosensing. Conclusion This hammock strategy provides an easily accessible and tunable cell culture platform for mimicking distal lung mechanical forces in vitro. We anticipate the promise of this culture platform for mechanistic studies, multi-modal stimulation, and drug or small molecule testing, extendable to other cell types and organ systems.
Developable surfaces based on closed‐shape, planar, rotationally symmetric kirigami (RSK) sheets approximate 3D, globally curved surfaces upon (reversible) out‐of‐plane deflection. The distribution ...of stress and strain across the structure is characterized experimentally and by finite‐element analysis as a function of the material and cut parameters, enabling the integration with strain gauges to produce a wearable, conformal patch that can capture complex, multiaxis motion. Using the patch, real‐time tracking of shoulder joint and muscle behavior is demonstrated. The facile fabrication and unique properties of the RSK structures potentially enable wearable, textile‐integrated joint monitoring for athletic training, wellness, rehabilitation, feedback control for augmented mobility, motion of soft and traditional robotics, and other applications.
This work introduces a new paradigm for realizing 2D to curved, 3D, functional surface transformation using rotationally symmetric kirigami as a platform for deploying wearable sensors; here it is demonstrated for real‐time tracking of complex motion of joints within the body and circumventing longstanding tradeoffs in the design of materials, structures, and devices for conformable, wearable electronics.
Electrohydrodynamic jet (e‐jet) printing is a high‐resolution additive manufacturing technique that holds promise for the fabrication of customized micro‐devices. In this companion paper set, e‐jet ...printing is investigated for its capability in depositing multilayer thin‐films with microscale spatial resolution and nanoscale thickness resolution to create arrays of 1D photonic crystals (1DPC). In this paper, an empirical model for the deposition process is developed, relating process and material parameters to the thickness and uniformity of the patterns. Standard macroscale measurements of solid surface energy and liquid surface tension are used in conjunction with microscale contact angle measurements to understand the length scale dependence of material properties and their impact on droplet merger into uniform microscale thin‐films. The model is validated with several photopolymer inks, a subset of which is used to create pixelated, multilayer arrays of 1DPCs with uniformity and resolution approaching standards in the optics manufacturing industry. It is found that the printed film topography at the microscale can be predicted based on the surface energetics at the microscale. Due to the flexibility in design provided by the e‐jet process, these findings can be generalized for fabricating additional multimaterial, multilayer micro‐ and nanostructures with applications beyond the field of optics.
Herein, electrohydrodynamic jet (e‐jet) printing is investigated for its capability in depositing thin‐film, multi‐material, layered microstructures. An empirical model for the deposition process is developed, relating process and material parameters to film thickness. Standard macroscale measurements of surface energy and surface tension are used in conjunction with microscale contact angle measurements to understand material behaviors at the microscale.
The thermal conductivities of crystalline and amorphous CuPc structures have been studied using molecular dynamics simulations. To this end, a Hybrid-COMPASS force field for the CuPc molecule has ...been developed and parametrized using ab initio and empirical parametrization techniques. The valence parameters and atomic partial charges were derived by fitting to ab initio calculation results, and the van der Waals (vdW) parameters were derived by comparing MD simulations of CuPc crystal structures to experimentally determined characteristics. The resulting force field successfully predicts accurate molecular structure, crystal structure, and vibration density of states (VDOS) of CuPc molecule in isolation and in condensed phase. Thermal conductivities calculated using the Green–Kubo formalism show a significant difference between crystalline and amorphous CuPc. Further analysis of the thermal conductivity spectral modes reveals that this difference mainly stems from the scattering of acoustic phonons, and to a lesser extent from the suppression of optical phonon modes in the amorphous structure. Accordingly, phonon scattering at amorphous domain walls in nanocrystalline materials effectively eliminates nearly two-thirds of conduction pathways.
Parylene films are commonly used as transparent, flexible coatings in electronic devices and biomedical applications, exhibiting barrier properties against corrosion, low dielectric constant, and ...moisture resistance. Reactive vapor deposition of parylene results in conformal coverage of features at room temperature, which is advantageous for passivating, for example, organic optoelectronic devices. Conventional parylene deposition methods, however, coat surfaces virtually indiscriminately and utilize separate chambers for vaporization, pyrolysis, and polymerization, resulting in a large footprint and limited processing integration ability, especially at a laboratory scale. Here, we demonstrate the vaporization and pyrolysis of the di-p-xylylene (parylene dimer) in a single compact nozzle, producing a jet of monomer that polymerizes into a film upon contact with the substrate at room temperature. A guard flow jet is employed to shield the reactive monomer molecules en route to the substrate, thereby enabling polymer deposition and patterning in ambient atmosphere. We present an analytical model predicting film growth rate as a function of process parameters (e.g., gas flow rate and source, pyrolysis & substrate temperatures). The effect of jet flow dynamics on film morphology is also discussed. A 100% increase in the lifetime of air-sensitive OLEDs is demonstrated upon encapsulation of the devices with parylene-N film deposited by this technique. Potential advantages of this approach include increased material utilization efficiency, localized conformal coating capabilities, and an apparatus that is compact, inexpensive, and does not require vacuum.
Circular supply chains require more accurate product labeling and traceability. In the apparel industry, product life cycle management is hampered in part by inaccurate, poorly readable, and ...detachable standard care labels. Instead, this article seeks to enable a labeling system capable of being integrated into the fabric itself, intrinsically recyclable, low‐cost, encodes information, and allows rapid readout after years of normal use. In this work, all‐polymer photonic crystals are designed and then fabricated by thermal drawing with >100 layers having sub‐micrometer individual thickness and low refractive index contrast (Δn = 0.1). The fibers exhibit reflectance features in the 1–5.5 µm wavelength range, characterized using insitu Fourier transform infrared spectroscopy. Drawn photonic fibers are then woven into fabrics, characterized by near‐infrared spectroscopy and short‐wave infrared imaging, techniques commonly used in industrial facilities for sorting materials. The fibers’ optical design also enables the use of overtone peaks to avoid overlap with parasitic molecular absorption, substantially improving the signal‐to‐noise ratio (and therefore ease and speed) of readout. The ability to produce kilometers of fiber that are compatible with existing textile manufacturing processes, coupled with low input material cost, make these a potential market‐viable improvement over the standard care label.
Over 85% of textiles currently end up in landfills, despite a recent study indicating 74% of low‐value, post‐consumer textiles could be recovered via fiber‐to‐fiber recycling. A key challenge in implementing fiber‐to‐fiber recycling is feedstock ambiguity, and in this work, a polymeric photonic tracer fiber is proposed as a method to enable more efficient life cycle tracing and sorting.
PDF
