Capacitance of Flexible Polymer/Graphene Microstructures with High Mechanical Strength.

Carbon-modified fibrous structures with high biocompatibility have attracted much attention due to their low cost, sustainability, abundance, and excellent electrical properties. However, some carbon-based materials possess low specific capacitance and electrochemical performance, which pose significant challenges in developing electronic microdevices. In this study, we report a microfluidic-based technique of manufacturing alginate hollow microfibers incorporated by water dispersed modified graphene (bovine serum albumin-graphene).

Hydrodynamic Assembly of Astrocyte Cells in Conductive Hollow Microfibers.

The manufacturing of 3D cell scaffoldings provides advantages for modeling diseases and injuries as it enables the creation of physiologically relevant platforms. A triple-flow microfluidic device is developed to rapidly fabricate alginate/graphene hollow microfibers based on the gelation of alginate induced with CaCl . This five-channel microdevice actualizes continuous mild fabrication of hollow fibers under an optimized flow rate ratio of 300:200:100 µL min .

Machine learning-assisted E-jet printing for manufacturing of organic flexible electronics.

Electrohydrodynamic-jet (E-jet) printing technique enables the high-resolution printing of complex soft electronic devices. As such, it has an unmatched potential for becoming the conventional technique for printing soft electronic devices. In this study, the electrical conductivity of the E-jet printed circuits was studied as a function of key printing parameters (nozzle speed, ink flow rate, and voltage).

Targeted Microfluidic Manufacturing to Mimic Biological Microenvironments: Cell-Encapsulated Hollow Fibers.

At present, the blood-brain barrier (BBB) poses a challenge for treating a wide range of central nervous system disorders; reliable BBB models are still needed to understand and manipulate the transfer of molecules into the brain, thereby improving the efficiency of treatments. In this study, hollow, cell-laden microfibers are fabricated and investigated as a starting point for generating BBB models. The genetic effects of the manufacturing process are analyzed to understand the implications of encapsulating cells in this manner.

Minute-sensitive real-time monitoring of neural cells through printed graphene microelectrodes.

Real-time and high-throughput cytometric monitoring of neural cells exposed to injury mechanisms is invaluable for in-vitro studies. Electrical impedance spectroscopy via microelectrode arrays is a label-free technique for monitoring of neural growth and their detachment upon death. In this method, the interface material plays a vital role to provide desirable attachment cues for the cell network.

Microfluidic Seeding of Cells on the Inner Surface of Alginate Hollow Microfibers.

Mimicking microvascular tissue microenvironment in vitro calls for a cytocompatible technique of manufacturing biocompatible hollow microfibers suitable for cell-encapsulation/seeding in and around them. The techniques reported to date either have a limit on the microfiber dimensions or undergo a complex manufacturing process. Here, a microfluidic-based method for cell seeding inside alginate hollow microfibers is designed whereby mouse astrocytes (C8-D1A) are passively seeded on the inner surface of these hollow microfibers.

Graphene Microelectrodes for Real-Time Impedance Spectroscopy of Neural Cells.

Understanding the changes in the electrochemical properties of neural cells upon exposure to stress factors imparts vital information about the conditions prior to their death. This study presents a graphene-based biosensor for real-time monitoring of N27 rat dopaminergic neural cells which characterizes cell adhesion and cytotoxicity factors through impedance spectroscopy. The aim was to monitor the growth of the entire cell network via a nonmetallic flexible electrode array.

Behavior of Neural Cells Post Manufacturing and After Prolonged Encapsulation within Conductive Graphene-Laden Alginate Microfibers.

Engineering conductive 3D cell scaffoldings offer advantages toward the creation of physiologically relevant platforms with integrated real-time sensing capabilities. Dopaminergic neural cells are encapsulated into graphene-laden alginate microfibers using a microfluidic approach, which is unmatched for creating highly-tunable microfibers. Incorporating graphene increases the conductivity of the alginate microfibers by 148%, creating a similar conductivity to native brain tissue.

Protein-assisted scalable mechanochemical exfoliation of few-layer biocompatible graphene nanosheets.

A facile method to produce few-layer graphene (FLG) nanosheets is developed using protein-assisted mechanical exfoliation. The predominant shear forces that are generated in a planetary ball mill facilitate the exfoliation of graphene layers from graphite flakes. The process employs a commonly known protein, bovine serum albumin (BSA), which not only acts as an effective exfoliation agent but also provides stability by preventing restacking of the graphene layers.

The influence of spacer composition on thermomechanical properties, crystallinity, and morphology in ionene segmented copolymers.

A series of segmented ammonium ionenes with varying weight fractions of 2000 g mol-1 poly(ethylene glycol) (PEG) or poly(tetramethylene oxide) (PTMO) soft segments were synthesized, and a simplified coarse-grained model of these materials was implemented using molecular dynamics simulations. In addition to varying soft segment type (PTMO vs. PEG), charge density and soft segment content were varied to create a comprehensive series of segmented ammonium ionenes; thermogravimetric analysis reveals that all segmented ionenes in the series are thermally stable up to 240 °C.

Recent Advances in Microfluidically Spun Microfibers for Tissue Engineering and Drug Delivery Applications.

In recent years, the unique and tunable properties of microfluidically spun microfibers have led to tremendous advancements for the field of biomedical engineering, which have been applied to areas such as tissue engineering, wound dressing, and drug delivery, as well as cell encapsulation and cell seeding. In this article, we analyze the most recent advances in microfluidics and microfluidically spun microfibers, with an emphasis on biomedical applications. We explore in detail these new and innovative experiments, how microfibers are made, the experimental purpose of making microfibers, and the future work that can be done as a result of these new types of microfibers.

Advancement of Sensor Integrated Organ-on-Chip Devices.

Organ-on-chip devices have provided the pharmaceutical and tissue engineering worlds much hope since they arrived and began to grow in sophistication. However, limitations for their applicability were soon realized as they lacked real-time monitoring and sensing capabilities. The users of these devices relied solely on endpoint analysis for the results of their tests, which created a chasm in the understanding of life between the lab the natural world.

Characterization of Astrocytic Response after Experiencing Cavitation In Vitro.

When a traumatic brain injury (TBI) occurs, low-pressure regions inside the skull can cause vapor contents in the cerebral spinal fluid (CSF) to expand and collapse, a phenomenon known as cavitation. When these microbubbles (MBs) collapse, shock waves are radiated outward and are known to damage surrounding materials in other applications, like the steel foundation of boat propellers, so it is alarming to realize the damage that cavitation inflicts on vulnerable brain tissue. Using cell-laden microfibers, the longitudinal morphological response that mouse astrocytes have to surrounding cavitation in vitro is visually analyzed.

Active Transiency: A Novel Approach to Expedite Degradation in Transient Electronics.

Transient materials/electronics is an emerging class of technology concerned with materials and devices that are designed to operate over a pre-defined period of time, then undergo controlled degradation when exposed to stimuli. Degradation/transiency rate in solvent-triggered devices is strongly dependent on the chemical composition of the constituents, as well as their interactions with the solvent upon exposure. Such interactions are typically slow, passive, and diffusion-driven.

Study of Partially Transient Organic Epidermal Sensors.

In this study, an all-organic, partially transient epidermal sensor with functional poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conjugated polymer printed onto a water-soluble polyethylene oxide (PEO) substrate is studied and presented. The sensor's electronic properties were studied under static stress, dynamic load, and transient status. Electrode resistance remained approximately unchanged for up to 2% strain, and increased gradually within 6.

High-Yield Production of Aqueous Graphene for Electrohydrodynamic Drop-on-Demand Printing of Biocompatible Conductive Patterns.

Presented here is a scalable and aqueous phase exfoliation of graphite to high yield and quality of few layer graphene (FLG) using Bovine Serum Albomine (BSA) and wet ball milling. The produced graphene ink is tailored for printable and flexible electronics, having shown promising results in terms of electrical conductivity and temporal stability. Shear force generated by steel balls which resulted in 2-3 layer defect-free graphene platelets with an average size of hundreds of nm, and with a concentration of about 5.

Hybrid Cellulose-Glass Fiber Composites for Automotive Applications.

In the recent years, automakers have been striving to improve the carbon footprint of their vehicles. Sustainable composites, consisting of natural fibers, and/or recycled polymers have been developed as a way to increase the "green content" and reduce the weight of a vehicle. In addition, recent studies have found that the introduction of synthetic fibers to a traditional fiber composite such as glass filled plastics, producing a composite with multiple fillers (hybrid fibers), can result in superior mechanical properties.

Placenta-on-a-Chip: In Vitro Study of Caffeine Transport across Placental Barrier Using Liquid Chromatography Mass Spectrometry.

Due to the particular structure and functionality of the placenta, most current human placenta drug testing methods are limited to animal models, conventional cell testing, and cohort/controlled testing. Previous studies have produced inconsistent results due to physiological differences between humans and animals and limited availability of human and/or animal models for controlled testing. To overcome these challenges, a placenta-on-a-chip system is developed for studying the exchange of substances to and from the placenta.

Viability of Neural Cells on 3D Printed Graphene Bioelectronics.

Parkinson's disease (PD) is the second most common neurodegenerative disease in the United States after Alzheimer's disease (AD). To help understand the electrophysiology of these diseases, N27 neuronal cells have been used as an in vitro model. In this study, a flexible graphene-based biosensor design is presented.

Photo-Cross-Linked Poly(ethylene glycol) Diacrylate Hydrogels: Spherical Microparticles to Bow Tie-Shaped Microfibers.

Bow tie-shaped fibers and spherical microparticles with controlled dimensions and shapes were fabricated with poly(ethylene glycol) diacrylate hydrogel utilizing hydrodynamic shear principles and a photopolymerization strategy under a microfluidic regime. Decreasing the flow rate ratio between the core and sheath fluids from 25 (50:2) to 1.25 (100:80) resulted in increasing the particles size and reducing the production rate by 357 and 86%, respectively.

Microfluidic Manufacturing of Alginate Fibers with Encapsulated Astrocyte Cells.

Encapsulating cells within microfibers allows for immobilization with a high degree of spatial-temporal control. Furthermore, microfluidic encapsulation allows for the continuous creation of tunable fibers using mild, cell-friendly gelation conditions, making it advantageous over other fabrication methods. Mouse astrocyte cells (MACs) encapsulated within microfluidically produced alginate fibers had a 24 h survival rate of up to 89%, with up to 60% of cells surviving 11 days of encapsulation.

Study of Agave Fiber-Reinforced Biocomposite Films.

Thermoplastic resins (linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and polypropylene (PP)) reinforced by different content ratios of raw agave fibers were prepared and characterized in terms of their mechanical, thermal, and chemical properties as well as their morphology. The morphological properties of agave fibers and films were characterized by scanning electron microscopy and the variations in chemical interactions between the filler and matrix materials were studied using Fourier-transform infrared spectroscopy. No significant chemical interaction between the filler and matrix was observed.

3D Microfibrous Scaffolds Selectively Promotes Proliferation and Glial Differentiation of Adult Neural Stem Cells: A Platform to Tune Cellular Behavior in Neural Tissue Engineering.

Biomaterials are essential for the development of innovative biomedical and therapeutic applications. Biomaterials-based scaffolds can influence directed cell differentiation to improve cell-based strategies. Using a novel microfluidics approach, poly (ε-caprolactone) (PCL), is used to fabricate microfibers with varying diameters (3-40 µm) and topographies (straight and wavy).

Controlled positioning of microbubbles and induced cavitation using a dual-frequency transducer and microfiber adhesion techniques.

We report a study on two methods that enable spatial control and induced cavitation on targeted microbubbles (MBs). Cavitation is known to be present in many situations throughout nature. This phenomena has been proven to have the energy to erode alloys, like steel, in propellers and turbines.

Microfibers as Physiologically Relevant Platforms for Creation of 3D Cell Cultures.

Microfibers have received much attention due to their promise for creating flexible and highly relevant tissue models for use in biomedical applications such as 3D cell culture, tissue modeling, and clinical treatments. A generated tissue or implanted material should mimic the natural microenvironment in terms of structural and mechanical properties as well as cell adhesion, differentiation, and growth rate. Therefore, the mechanical and biological properties of the fibers are of importance.