Kshirasagar, Saniya Sanjay and Unni, H N
(2018)
Digital Microfluidic (DMF) devices based on
electrowetting on dielectric (EWOD) for biological
applications.
Masters thesis, Indian Institute of Technology, Hyderabad.
Abstract
Microfluidic devices have been used in various applications including automated analysis systems,
biological applications like DNA sequencing, antigen-antibody reactions, protein studies, chemical
applications, single cell studies, etc.
Microfluidic devices are primarily categorised into two types. First are continuous microfluidic
devices. These devices consist of predefined microchannels, micro-valves, and syringe pumps. Fluid
is continuously flowing in these channels. The second type is digital microfluidic platforms. In this
type, MXN array of electrodes is patterned on non-conducting substrate. Fluid is discretized to
form tiny droplets. These droplets are transported, mixed and split using external electric field.
Digital microfluidic devices are configurable as there are no permanently etched channels. Also,
they have high throughput. Multiple reactions can be performed on the same platform at the same
time. The time taken to complete one reaction is less compared to the continuous devices. Thus they
help in faster analysis. These devices are controlled by electrical field and thus unlike continuous
devices, digital microfluidic devices are free from mechanically moving parts.
Digital microfluidic devices may suffer from charge accumulation due to electrostatic forces. Also,
voltage levels applied play an important role. The applied voltage has to be enough to move droplets
but should not cause electrolysis of the liquid used. Also voltage switching time between electrodes
and frequency applied are important. These parameters can change the mixing quality. In this
work, 2D simulations of droplet manipulation due to voltage application, transport and mixing are
carried out. Also digital microfluidic device is designed and fabricated to carry out biological mixing
experiments.
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