Definitions

Microfluidic chips are usually fabricated by making thin grooves or small wells on the surface of a layer, and then enclosing those features by means of a second layer to form microchannels or chambers. Channels need to be leak-proof thus the layers must be properly bonded. Depending on material choice, the channels are made via soft lithography, hot embossing, injection molding, micro-machining, or etching. 3D printing may be used for producing microfluidic chips, although it has serious limitations in terms of minimum feature size, surface roughness, optical transparency, or choice of material.

There are several reasons to use microfluidics. First, to make use of a small size scale in the range of microns. For every 3D shape type, e.g. a rectangular channel or chamber, the ratio of surface area to volume increases as size decreases. This makes it favourable for microchannels to captures targets such as cells, germs or nanoparticles. Alternatively, Magnetic or Electric fields are more effective at a short distance, making microfluidics ideal for sensing or detecting. Ability to visualize and characterize small objects such as living cells is another advantage of microfluidics. Microfluidics is also used to miniaturize or integrate conventional laboratory practices by making lab on a chip devices to save cost or reduce time.

Microfluidics has application in most experimental science and engineering. Examples are molecular and cell biology research, genetics, fluid dynamics, micro-mixing, Point of Care Diagnostics, Lab on a Chip, Tissue engineering, Organ on a Chip, drug delivery device, fertility testing and assistance, synthesis of chemicals or proteins.

Droplet-based microfluidic has recently emerged as a powerful tool in the microfluidics domain. Droplet microfluidic devices generate droplets of tiny volumes (nL to fL). There are three major applications for droplet microfluidics; molecular biology, microparticle synthesis, and microorganism studies. In molecular biology, droplets serve as bioreactors. Single cells are entrapped in the droplets where they experience a series of reactions where each droplet can be analyzed individually. For microparticle synthesis, the droplets are often made of hydrogels and are solidified after generation using a photo, chemical, or thermal technique. In microorganism studies, the microorganisms are encapsulated within droplets for analyzing their responses to various reagents for drug development.

A biochip is a small device that directly connects an organism to an engineering system. To do so, biochips often include tiny built-in sensors that analyze biochemical targets in organisms such as cells, blood, or skin. Biochips utilize a wide array of technological advances such as microfluidics, microarrays, optics, or electronics. Current applications of biochips are in disease diagnostics, security, and gene sequencing, with many new applications emerging.

A DNA chip is a device usually size of a microscope slide containing thousands of pre-defined spots. Each of these spots hosts a unique probe that can bind to a specific target gene sequence. When a sample such as prepared and purified blood comes in contact with the surface of the DNA Chip, the matching gene in the sample can pair with the probes on the DNA Chip. The researcher, then, uses a computer program to analyze the position of the spots to identify targets such as pathogens, mutations, etc.. in the sample.