You are probably reading these words on a mobile phone, tablet or laptop – all highly portable computers. The Digital Revolution was ushered in fifty years ago and since then, integrated circuits miniaturized computers from something that took up an entire room to something that could sit on a desk. Now, computers are everywhere—in our homes, in our cars, and in our pockets—automatically processing and calculating to get us the information we need quickly.
Chemistry and biology labs as well as medical diagnostic labs still take up entire rooms and even buildings. But what if you could shrink down the lab to something that fits in your pocket, just like we did with computers? This is exactly what researchers at the University of Toronto are trying to do.
Professor Aaron Wheeler and his team are trying to miniaturize the chemistry and biology lab to something the size of a credit card. They work in the field of microfluidics—an area of physics, engineering, and chemistry that’s all about controlling and moving tiny volumes of liquids—and their specialty is a technology called digital microfluidics (DMF).
Let’s get digital!
In DMF, individual micro-droplets of liquid (0.5-2 microlitres) are manipulated using electrostatic forces, in a similar fashion to how a statically charged comb or balloon can bend a gentle stream of tap water. A DMF device, or “chip”, is made from two layers that sandwich the liquid. The bottom layer contains a grid system of electrodes that are covered by an insulator and a non-stick coating. The top layer is glass covered with a clear, conductive indium tin oxide coating, which is also given a further non-stick coating. When a voltage is applied between an electrode in the bottom layer and the top layer, a charge builds up in the insulator and can “pull” a nearby droplet of liquid towards it.
The ability to manipulate individual droplets enables researchers to mimic a lot of the same liquid handling procedures used in a traditional lab—they can split, move, and combine droplets to do all sorts of reactions. Because droplets are manipulated by the application of voltages, these chips can be connected to computers and automated. The individual droplets and procedures can be programmed to do a number of functions, just like bits in a computer program are used for different functions.
Mini labs, global problems
These miniature “lab-on-a-chip” devices can be used for a whole host of experiments. One application is disease diagnostics. Because these mini labs can mimic the same procedures of big labs, they can get the same accurate results in less time and with smaller samples. Recently, a team from the Wheeler Lab returned from Kakuma Refugee Camp in Kenya, where they were using their lab-on-a-chip to test infection and immunity status of patients as part of a vaccination campaign. The portability of their chip and control system means that mini diagnostic labs could be setup at the site of an outbreak rather than having to send samples back to a centralized lab.
Maybe one day, along with mobile phones in our pockets, we will carry around tiny labs that can do all sorts of tests and experiments for us, yielding accurate chemical information about ourselves and the world around us.