{"id":2653,"date":"2019-01-30T09:46:50","date_gmt":"2019-01-30T14:46:50","guid":{"rendered":"http:\/\/ufluidix.com\/circlesecond\/?p=2653"},"modified":"2019-10-09T14:40:23","modified_gmt":"2019-10-09T18:40:23","slug":"a-brief-introduction-to-digital-microfluidics","status":"publish","type":"post","link":"https:\/\/www.ufluidix.com\/circle\/a-brief-introduction-to-digital-microfluidics\/","title":{"rendered":"A Brief Introduction to Digital Microfluidics"},"content":{"rendered":"

In the early 1900s when digitization of data came about to be a boom in data processing technology, one wouldn’t have imagined that similarly a droplet containing biological samples could be digitized in order to be processed in a programmed order of complex reactions. Digital microfluidics (DMF) has made it possible to perform a stepwise procedure on precise quantities of liquid on a microscale thereby combining the benefits of microfluidics<\/a> as well as discrete processing of information.<\/p>\n

The digitization is achieved by a technology called electro-wetting on dielectric (EWOD). As the name suggests, EWOD involves “electric field” and “wetting of dielectric”, later as a result of the former. The ability to capture liquid droplets on a layer of dielectric using electric field help achieve the DMF control. In DMF, picoliter- to microliter-sized droplets are independently addressed on an open array of electrodes coated with a hydrophobic insulator1<\/a><\/sup><\/span>. The EWOD device used for DMF mainly consists of multiple layers stacked intelligently to form a simple circuit [Figure 1].<\/p>\n

\"Schematic<\/a>

Figure 1. Schematic cross-section of a typical EWOD device showing all layers7<\/a><\/sup><\/span>.<\/p><\/div>\n

The figure shows a two plate EWOD device. The bottom plate consists of electrodes and a dielectric layer and the top plate consists of a common grounded electrode. The circuit is broken as long as there is air between these two plates, but the circuit is completed when an electrode under a droplet is supplied with high voltage. This is due to the fact that the ions in the droplet provide a medium for conduction through the droplet. The droplet along with the capacitive dielectric layer and the electrode form the total impedance of the circuit. Once the electrode is supplied with high voltage it causes a decrease in the contact angle of the droplet and thereby making the droplet to stick to the electrode. Further, by switching the supply to the adjacent electrode the droplet can be moved to that electrode, establishing movement on the plate. This movement on droplet can be in order to move, mix two drops, split a bigger drop into two smaller droplets which are the basic functions to carry out a bioassay on the chip (watch a video below).<\/p>\n