Microfluidic Gastrointestinal Cell Culture Technologies-Improvements in the Past Decade.

Gastrointestinal cell culture technology has evolved in the past decade with the integration of microfluidic technologies, bringing advantages with greater selectivity and cost effectiveness. Herein, these technologies are sorted into three categories, namely the cell-culture insert devices, conventional microfluidic devices, and 3D-printed microfluidic devices. Each category is discussed in brief with improvements also discussed here.

Core-Shell Particles: From Fabrication Methods to Diverse Manipulation Techniques.

Core-shell particles are micro- or nanoparticles with solid, liquid, or gas cores encapsulated by protective solid shells. The unique composition of core and shell materials imparts smart properties on the particles. Core-shell particles are gaining increasing attention as tuneable and versatile carriers for pharmaceutical and biomedical applications including targeted drug delivery, controlled drug release, and biosensing.

Fabrication and characterization of core-shell microparticles containing an aqueous core.

Core-shell microparticles containing an aqueous core have demonstrated their value for microencapsulation and drug delivery systems. The most important step in generating these uniquely structured microparticles is the formation of droplets and double emulsion. The droplet generator must meet the performance and reliability requirements, including accurate size control with tunability and monodispersity.

Acoustic Biosensors and Microfluidic Devices in the Decennium: Principles and Applications.

Lab-on-a-chip (LOC) technology has gained primary attention in the past decade, where label-free biosensors and microfluidic actuation platforms are integrated to realize such LOC devices. Among the multitude of technologies that enables the successful integration of these two features, the piezoelectric acoustic wave method is best suited for handling biological samples due to biocompatibility, label-free and non-invasive properties. In this review paper, we present a study on the use of acoustic waves generated by piezoelectric materials in the area of label-free biosensors and microfluidic actuation towards the realization of LOC and POC devices.

Realization of Three-Dimensionally MEMS Stacked Comb Structures for Microactuators Using Low-Temperature Multi-Wafer Bonding with Self-Alignment Techniques in CMOS-Compatible Processes.

A high-aspect-ratio three-dimensionally (3D) stacked comb structure for micromirror application is demonstrated by wafer bonding technology in CMOS-compatible processes in this work. A vertically stacked comb structure is designed to circumvent any misalignment issues that could arise from multiple wafer bonding. These out-of-plane comb drives are used for the bias actuation to achieve a larger tilt angle for micromirrors.

Development of a Microfluidic Droplet-Based Microbioreactor for Microbial Cultivation.

Droplet microfluidics creates new opportunities for microbial engineering. Most microbial cultivations are carried out in bioreactors, which are usually bulky and consume a large amount of reagents and media. In this paper, we propose a microfluidic droplet-based microbioreactor for microbial cultivation.

On-Demand Droplet Merging with an AC Electric Field for Multiple-Volume Droplet Generation.

We introduce a unique system to achieve on-demand droplet merging and splitting using a perpendicular AC electric field. The working mechanism involves a micropillar to split droplets, followed by electrocoalescence using an AC electric field. Adjusting the parameters of the AC signal and conductivity of the fluid result in different merging regimes.

Influence of Interfacial Gas Enrichment on Controlled Coalescence of Oil Droplets in Water in Microfluidics.

Interfacial gas enrichment (IGE) of dissolved gases in water is shown to govern the strong attraction between solid hydrophobic surfaces of an atomic force microscopy (AFM) colloidal probe and solid substrate. However, the role of IGE in controlling the attraction between fluid-fluid interfaces of foam films and emulsion films is difficult to establish by AFM techniques because of the extremely fast coalescence. Here, we applied droplet-based microfluidics to capture the fast coalescence event under the creeping flow condition and quantify the effect of IGE on the drainage and stability of water films between coalescing oil droplets.

Fundamentals of Differential Particle Inertial Focusing in Symmetric Sinusoidal Microchannels.

Focusing and separation of particles such as cells at high throughput is extremely attractive for biomedical applications. Particle manipulation based on inertial effects requires a high flow speed and thus is well-suited to high-throughput applications. Recently, inertial focusing and separation using curvilinear microchannels has been attracting a great amount of interest because of the linear structure for parallelization, small device footprint, superior particle-focusing performance, and easy implementation of particle separation.

Negative Pressure Induced Droplet Generation in a Microfluidic Flow-Focusing Device.

We introduce an effective method to actively induce droplet generation using negative pressure. Droplets can be generated on demand using a series of periodic negative pressure pulses. Fluidic network models were developed using the analogy to electric networks to relate the pressure conditions for different flow regimes.

Self-Aligned Interdigitated Transducers for Acoustofluidics.

The surface acoustic wave (SAW) is effective for the manipulation of fluids and particles at microscale. The current approach of integrating interdigitated transducers (IDTs) for SAW generation into microfluidic channels involves complex and laborious microfabrication steps. These steps often require full access to clean room facilities and hours to align the transducers to the precise location.

Polymeric Biomaterials for Medical Implants and Devices.

In this review article, we focus on the various types of materials used in biomedical implantable devices, including the polymeric materials used as substrates and for the packaging of such devices. Polymeric materials are used because of the ease of fabrication, flexibility, and their biocompatible nature as well as their wide range of mechanical, electrical, chemical, and thermal behaviors when combined with different materials as composites. Biocompatible and biostable polymers are extensively used to package implanted devices, with the main criteria that include gas permeability and water permeability of the packaging polymer to protect the electronic circuit of the device from moisture and ions inside the human body.