top of page
SCALE-UP OF MONODISPERSE DROPLETS VIA PARALLELIZATION
Droplet-based microfluidics has led to transformational new approaches in diverse areas including materials synthesis and high-throughput biological assays. However, the translation of droplet microfluidics technology into commercial applications requires scale-up of droplet generation from the laboratory (<10 mL/h) to the industrial (>1 L/h) scale. To address this challenge, we develop a three-dimensional monolithic elastomer device (3D MED) for mass production of monodisperse single droplets, gas bubbles, and core-shell emulsion. Using double-sided imprinting, 3D microchannels are formed in a single elastomer piece that has 1000 parallel flow focusing generators (k-FFGs). Compared to previous work that parallelizes droplet generation, the 3D MED eliminates the needs for alignment and bonding of multiple pieces and thus makes it possible to achieve the high flow rates and pressure necessary for the kilo-scale generation of droplets. Using this approach, we demonstrate mass production of water-in-oil (W/O) emulsion droplets at production rates as high as 1.5 L/h (>30 billion 45 μm diameter droplets per hour), with a coefficient of variation of droplet diameter of around 5.0%. Because of the simplicity, robustness, and manufacturability of our 3D MED architecture, it is well suited to bridge the gap between the continuously growing library of promising microfluidic technologies to generate microparticles that have been demonstrated in laboratory settings and their successful application in industry.
A HIGHLY ADDRESSABLE AND PROGRAMMABLE STATIC DROPLET ARRAY
Droplet-based microfluidics enabling exquisite liquid-handling has been developed for diagnosis, drug discovery and quantitative biology. Compartmentalization of samples into a large number of tiny droplets is a great approach to perform multiplex assays and to improve reliability and accuracy using a limited volume of samples. Despite significant advances in microfluidic technology, individual droplet handling in picovolume resolution is still a challenge in obtaining more efficient and varying multiplex assays. We present a microfluidic static droplet array (SDA) that combines a droplet generator with hydrodynamic traps to independently generate a bacterial population gradient into a parallel series of droplets under complete chemical and physical isolation. The SDA independently manipulates both a chemical concentration gradient and a bacterial population density. In addition, the bacterial population gradient in the SDA can be tuned by a simple change in the number of sample plug loading. Also, we present a highly addressable static droplet array (SDA) enabling individual digital manipulation of a single droplet using a microvalve system. In a conventional single-layer microvalve system, the number of microvalves required is dictated by the number of operation objects; thus, individual trap-and-release on a large-scale 2D array format is highly challenging. By integrating double-layer microvalves, we achieve a “balloon” valve that preserves the pressure-on state under released pressure; this valve can allow the selective releasing and trapping of 7200 multiplexed pico-droplets using only 1 μL of sample without volume loss. This selectivity and addressability completely arranged only single-cell encapsulated droplets from a mixture of droplet compositions via repetitive selective trapping and releasing. Thus, it will be useful for efficient handling of miniscule volumes of rare or clinical samples in multiplex or combinatory assays, and the selective collection of samples.
BACTERIAL CHEMOTAXIS ASSAY USING MICROFLUIDIC DEVICE
Bacterial chemotaxis is a complex response to temporal changes of concentrations of chemoeffectors. Conventional methods,including microfluidic approaches,for the precise analysis of bacterial chemotaxis are limited in the accurate control of chemical gradients, low sensitivity, and longer analytical times although the advances in microfluidic technology provide a novel platform. Here,we present a diffusion-based microfluidic device to provide rapid diffusion of chemoeffectors using a liquid–liquid interface, which is a critical advance in the analysis of bacterial chemotaxis. The microfluidic method can rapidly analyze attractants and repellents, achieving a chemotaxis index corresponding to the concentrations and types of chemoeffectors. Moreover, we find that the dynamics witch in bacterial chemotaxis from attraction to repellence in response to specific chemoeffectors occurs in a concentration-dependent manner. Thus, our microfluidic method is promising and reliable for the analysis of bacterial chemotaxis.
PROFILING SURFACE GLYCANS ON TUMOR CELLS AND TISSUES ARRAYS
The surface of mammalian cells is densely coated with complex glycans, which are directly involved in cell–cell or cell–protein interactions that trigger various biological responses. Here, we present a novel glycomics approach that uses quantum dot (Qdot)-lectin nanoconjugates to interrogate the surface glycans of tissues and patterned cells. Our approach allows highly sensitive in situ monitoring of specific lectin–glycan interactions and quantitative information on surface glycans for each examined cell line and tissue. The results clearly show significant changes in glycosylation for each cell line and tissue sample. We expect that these results will be applicable in cancer diagnostics and promote the development of new analytical tools for glycomics.
bottom of page