- This system is divided into two category: (1) Digital Microfluidics (2) Continuous Microfluidics
- The system has general user friendly GUI in which above both category operations can be performed
- For Digital Microfluidics operations on droplet, DMF Electronics Control Unit which contains programmable system with electromagnetic relay circuits for controlling voltage actuation is used. It is required to use DMF test chip to enable discrete electrodes actuation.
- For Continuous Microfluidics operation, Infusion Syringe Pumps along with tubings are used. It is required to use Continuous fluidics test chip preferably made up of PDMS/Si.
- The complete setup consists of USB Digital camera for capturing image/video in real time, XYZ stage for holding sample, Arm7 based electronic system which has standard circuits to provide actuation of voltage and to handle image processing along with HDMI display. The system is designed to achieve real time precise control over movement of droplet in real time embedded Linux platform
- The Contact Angle Measurement,Velocity Measurement, Volume Measurement, mixing efficiency on the developed samples are studied using our characterization setup.
PCB based Cu Electrodes for EWOD with Top Ground used for DMF
140µm PDMS serpentine Y Mixer used for continuous Microfluidics
50µm width Si Channel with Hexagonal micromixer
Hexagonal passive Si micromixer after PDMS glass bonding
What can you Do using This Instrument?
- Measurement of contact angle.
- Droplet Transporting and Merging in forward and Reverse Direction.
- Calculation of Mixing Efficiency of a merged droplet.
- Velocity Measurement of a transported droplet.
- Volume Measurement of a static droplet.
- Observe the laminar behavior of fluids when mixing
Contact Angle Measurement:
The contact angle is defined as the angle formed by the intersection of the liquid-solid interface and liquid-vapor interface device has been characterized through contact angle measurements using Scilab in open configuration.For contact angle measurement digital camera should be placed horizontally whereas proper ground must be provided to the droplet by means of an overhead catena. For measuring contact angle variation with respect to the voltage the droplet should be in contact with the vertical ground electrode. Contact angle changes with respect to voltage of different devices with different dielectric thickness can be measured.
Droplet position while measuring contact angle
Variation of contact angle with respect to different actuation of voltage with theoretical and practical comparison
Droplets merging and Mixing Efficiency Calculation:
Place the two water droplets of nearly same size on 3 adjacent electrodes in such a way that the two droplets overlap the central electrode. Now the electrodes at the end aregrounded and the central electrode is activated by applying DC voltage. We can observe that the two droplets get merged at 150 volts for the PCB based copper electrodes. If the Voltage further increased beyond, one can observe that the merged droplet rearrange itself in circular shape over the central electrode.
Merging of two droplets.
Place a discrete droplet on any electrodesuch a way that it partially overlapped with the neighboring electrode and ground the droplet itself with one probe.The electrode below the droplet is actuated with 200Vto create an interfacial energy gradient at droplet-dielectric (solid) interface between the portion overlapping with actuated electrode and rest. Thus the droplet tends to realign itself completely over the actuated electrode
Droplet Transporting in (a) forward direction (b) reverse direction
A droplet of unknown volume can be placed in a substrate and its side view can be captured as an image using camera. Then the captured Image should be processed using customized code developed in Scilab which is pre-installed in our setup.
Velocity of a transported droplet/particle in a flow can be measured using ImageJ pluggin which is freely available under GNU license. To do that one should transport the droplet/particle using above mentioned way or using external means like pumps and capture the video of 30fps and extract the frames using our GUI.
Velocity measurement for (a)Forward velocity for all cases (b) Reverse velocity for all cases
- Output Voltage range(DC):10V to 300V
- Simultaneous control of voltage over 8 Channel
- Magnification Range of camera 25 X ~ 200X (Manually)
- Camera Frame Rate 30 f/s
- White-light LED strip for adjustable illumination of camera.
- XY linear movement stage for sample:
- Ethernet Port
- 4 USB ports for interfacing of mouse, keyboard, Camera etc.
- Z movement stand for camera
- User Friendly
- Camera Interface
- Control Software enables Contact angle Measurement and Velocity measurement Using ImageJ, Calculation of mixing Efficiency using Scilab.
Input Power:190~280 volts AC,50 Hz
- Micro-mixing of binary liquids.
- MEMS based experimental kit.
- Chemical Analysis
Manual XY Stage
USB Microscope Camera
Z stage for camera movement