Definitions

Find the answers to frequently asked questions about microfluidics

What is microfluidics?

Microfluidics relates to design and study of devices which move or analyze the tiny amount of liquid, smaller than a droplet. Microfluidic devices have microchannels ranging from submicron to few millimetres. To compare, a human hair is about 100 microns thick. Microfluidics has been increasingly used in the biological sciences because precise and controlled experiments can be conducted at a lower cost and faster pace. Lab on a Chip devices use microfluidics for applications such as Point of Care testing of diseases, or Organ on a Chip studies.

How do microfluidics work?

Microfluidics systems work by using a pump and a chip. Different types of pump precisely move liquid inside the chip with the rate of 1 μL/minute to 10,000 μL/minute. For comparison, a small water drop is ~10 microliter (μL). Inside the chip, there are microchannels that allow the processing of the liquid such as mixing, chemical or physical reactions. The liquid may carry tiny particles such as cells or nanoparticles. The microfluidic device enables the processing of these particles, for example, trapping and collection of cancer cells from normal cells in the blood.

What is a microfluidic chip?

A microfluidic chip is a device that enables a tiny amount of liquid to be processed or visualized. The chip is usually transparent and its length or width are from 1 cm (0.5″) to 10 cm (4″). The chip thickness ranges from about 0.5 mm (1/64″) to 5 mm (1/4″). Microfluidic chips have internal hair-thin microchannels that are connected to outside by means of holes on the chip called inlet/outlet ports. Microfluidic chips are made from thermoplastics such as acrylic, glass, silicon, or a transparent silicone rubber called PDMS.

How to make a microfluidic chip?

Microfluidic chips are usually made 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.

Why use microfluidics?

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.

What are the microfluidics applications?

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.

What is droplet-based microfluidics?

Droplet-based microfluidic has recently emerged as a powerful tool in 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 hydrogel and are solidified after generation using a photo, chemical, or thermal techniques. In microorganism studies, the microorganisms are encapsulated within droplets for analyzing their response to various reagents for drug development.

What is a biochip?

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 which 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.

What is a DNA chip?

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.