Browsing by Author "Karingula, Varun Kumar"

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    AFM-Based Fabrication of Nanofluidic Device for Medical Application
    (Office of the Vice Chancellor for Research, 2014-04-11) Promyoo, Rapeepan; El-Mounayri, Hazim; Karingula, Varun Kumar
    Recent developments in science and engineering have advanced the atomic manufacture of nanoscale structures, allowing for improved high-performance technologies. Among them, AFM-based nanomachining is considered a potential manufacturing tool for operations including machining, patterning, and assembling with in situ metrology and visualization. In this work, atomic force microscope (AFM) is employed in the fabrication of nanofluidic device for DNA stretching application. Nanofluidic channels with various depths and widths are fabricated using AFM indentation and scratching techniques. To introduce the fluid inside the nanochannels, microchannels are made on both sides of the nanochannels. Photolithography technique is used to fabricate microfluidic channels on silicon wafers. A 3D Molecular Dynamics (MD) model is used to guide the design and fabrication of nanodevices through nanoscratching. The correlation between the scratching conditions, including applied force, scratching depth, and distant between any two scratched grooves and the defect mechanism in the substrate/workpiece is investigated. The MD model allows proper process parameter identification resulting in more accurate nanochannel size.
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    AFM-Based Nanofabrication: Modeling, Simulation, and Experimental Verification
    (Office of the Vice Chancellor for Research, 2013-04-05) Promyoo, Rapeepan; El-Mounayri, Hazim; Karingula, Varun Kumar; Varahramyan, Kody
    Recent developments in science and engineering have advanced the fabrication techniques for micro/ nanodevices. Among them, atomic force microscope (AFM) has already been used for nanomachining and fabrication of micro/nanodevices. In this paper, a computational model for AFM-based nanofabrication processes is being developed. Molecular Dynamics (MD) technique is used to model and simulate mechanical indentation and scratching at the nanoscale. The effects of AFM-tip radius and crystal orientation are investigated. The simulation is also used to study the effect of the AFM tip speed on the indentation force at the interface between the tip and the substrate/workpiece. The material deformation and indentation geometry are extracted from the final locations of atoms, which are displaced by the rigid indenter. Material properties including modulus of elasticity and hardness are estimated. It is found that properties vary significantly at the nanoscale. AFM is used to conduct actual nanoindentation and scratching, to validate the MD simulation. Qualitative agreement is found. Finally, AFM-based fabrication of nanochannels/nanofluidic devices is conducted using different applied forces, scratching length, and feed rate.
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    MANUFACTURING PROCESS OF NANOFLUIDICS USING AFM PROBE
    (2015-05) Karingula, Varun Kumar; HAZIM, EL-MOUNAYRI; ZHU, LIKUN; DECCA, RICARDO S.
    A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nano fluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.