Carbon microspheres with macro-meso-microporous hierarchical pore has increasingly become a subject of great interest, driven by the need to obtain high performing carbons in multidisciplinary fields,  such as lithium battery materials, catalyst carriers, capacitor electrode materials, adsorption materials and drug delivery. Numerous methods like arc discharge, hydrothermal , chemical vapor deposition and template are generally chosen to prepare carbon microspheres. However, these methods has poor experimental repeatability and wide particle size distribution. Notably, the droplet-based microfluidic technique is useful for the generation of various uniform microparticles, reducing the experimental errors and ensuring stability and quality.

To prepare uniform particles, we developed a novel plug-and-play coaxial microfluidic device . The capillary device was based on commercial components that can readily be assembled, adjusted and cleaned. In this device, regardless of  surface wettability of fluidic channel, monodisperse droplets with average diameter in the range of 50-800μm could be controllably prepared. This design strategy allows for generation of various granular material and simplifies the fabrication process to meet different conditions during preparation, which would be an attractive tool in the future.

By radical polymerization and two-phase shear flows in the microchannel, a three-dimensional network structure of light-cured spherical gel was formed . After high-temperature carbonization and activation , hybrid resin transformed to carbon and spherical carbon particles with well-balanced pore distribution and uniform size were obtained. Comparing the characterization results of various activation, it shows that carbon microspheres using chemical activation process have a richer microporous network. When the mass ratio of activator and carbon is 4:1, the pore size distribution is concentrated and the range of pore size is 0.5 to 0.8 nm, with a specific surface area up to 1800 m²/g, which implies great potential of engineering applications.

Microencapsulation of probiotics using biomaterials such as alginate is a highly effective strategy for probiotic delivery to prevent the degradation of probiotics from harsh conditions in the gastrointestinal tract.1, 2 This work demonstrates an efficient method for the encapsulation of anaerobic Lactobacillus probiotics in calcium cross-linked alginate microparticles by using on-chip microfluidics to form monodisperse and highly-stable microbeads. In this study, we performed the numerical simulation of the droplet formation method (Fig 1). Following this, we investigated the size variation of microdroplets with different ratios of flow rates of the dispersed and continuous phases (Fig 3). The morphology of the microparticles was characterized using optical microscopy and scanning electron microscopy (SEM). We assessed the viability of encapsulated bacteria using SYTO 9 dye and fluorescence microscopy. The chemical structure of the microparticles containing Lactobacillus was analyzed via Fourier transform infrared spectroscopy (FTIR). We also calculated the encapsulation efficiency of bacteria by measuring their survival after encapsulation. The survival rate percentage of encapsulated versus non-encapsulated probiotic cells was determined at various storage times (at 7, 14, 21 and 28 days). The results indicated the successful entrapment of Lactobacillus within highly stable and uniform microdroplets using the developed microfluidic platform. The optical microscopy and SEM images determined that the probiotic bacteria occupied almost all of the inner space of hydrogel alginate microbeads and the morphology of microparticles were regular spherical structures (Fig 2). Fluorescent images revealed the presence of living bacteria inside the microbeads (Fig 4). The encapsulation yield of the freshly prepared alginate microparticles was 86.95 %. The storage results confirmed that the encapsulated cells stored at -15 ºC showed a relatively high survival rate compared to free cells (Fig 6). SEM results indicated that bacterial cells were successfully entrapped, and freeze-dried microbeads exhibited irregularly shaped with cracks on the surface (Fig 5). The Lactobacillus-encapsulated in alginate microparticles also provided prolonged viability and enhanced shelf-life.  Taken together, the results demonstrate the promising potential of our microfluidic flow-focusing system to be used as a high-throughput single-step process that provides stable and uniform microparticles containing anaerobic probiotic bacteria.

A novel flow sensor is presented to measure the flow rate within microchannels in a real-time, noncontact and nonintrusive manner. This patented sensing technology can be further used in measuring a physical characteristic of a fluid in a microfluidic system. The sensing platform includes a microfluidic chip that has a thin deformable membrane that separates a microfluidic channel from a microwave resonator sensor. The membrane is deformable in response to loading from interaction of the membrane with the fluid. Loading may be fluid pressure in the channel, or shear stress or surface stress resulting from interaction of the membrane with the fluid. The deformation of the membrane changes the permittivity in the region proximate the sensor. A change in permittivity causes a change in the electrical parameters of the sensor, thereby allowing for a characteristic of the fluid, such as flow rate, or a biological or chemical characteristic, to be measured.