Ph.D. Thesis Colloquium

Dear All


                                         Ph.D. Thesis Colloquium 

NAME OF THE CANDIDATE   :  Mr. Vikrant Kumar Singh 

DEGREE                                   :  Ph.D.  

TITLE OF THE THESIS            :  Diamagnetically levitated nanopositioners: Development and Applications

SUPERVISOR                          :  Prof. G.R Jayanth 

DATE & TIME                           :  Tuesday, 26th October 2021 at 11:00 AM. 

VENUE                                      :  Online (Microsoft team) Link




    Precision positioning stages are indispensable in many branches of science and engineering, where they are employed for alignment, imaging, manipulation, and characterization. Compact, multi-degree-of-freedom stages with a large dynamic range are especially desirable since they improve the throughput, versatility in manipulation, and ease of integration with other instruments. However, most positioning technologies demand large compromises to be made on one or more of these fronts. This work describes compact diamagnetically levitated stages to achieve large-range and high precision six degrees-of-freedom (DOF) positioning.

    The first part of the talk describes the design and modelling of a diamagnetically levitated multi-DOF actuator. The actuator comprises a magnetic stage sandwiched between two current-carrying traces. The loads acting on the magnetic stage due to the actuating traces are derived, and it is shown that dual-sided actuation enables trapping a magnetic stage in 3-dimensions (3D), with independent control of the trap stiffness about two axes and independent application of forces in 3D and torques about 2 axes. Subsequently, a simplified model was proposed to obtain closed-form expressions for loads in terms of the actuation currents.

     The second part of the talk discusses the design of two novel six-axis positioners, based on these actuators. The first design uses four zones of actuating traces to apply a couple on an extended X-shaped magnetic stage and thus rotate it about the Z-axis. The second design employs compliant mechanisms integrated with two actuators to convert large range in-plane motion to large range out-of-plane motion. Subsequently, the dynamic modelling of the positioners and an analysis of the maximum volume of the stages are presented.

     The third part of the talk discusses the development of the positioning system, which includes the measurement system, the control system, and the positioners. The images acquired from the measurement system are digitally processed to make sub-pixel measurements of positioners’ motion. The resolution and range of the developed position measurement system are 1.85 ?? and 5.4 ?? respectively. The developed positioners demonstrate in-plane translational motion with a range of 5 mm and with positioning precision better than 1.88 nm and an angular motion range of 1.1 radians with a resolution of 50 micro-radian. The out-of-plane translational range has been shown to be 900 ??.

    The final part of the talk discusses the application of the developed nano-positioner for automated tip-replacement in Atomic Force Microscopy (AFM). It is worthwhile to note that the modular tip-replacement system can be retrofitted in a commercial microscope and is suitable for in-situ tip-replacement because of the small volume of the nano-positioner (10?20 ??3) and the compatibility of the developed tip-replacement module with the available commercial AFM cantilevers.


                                                         ALL ARE WELCOME 


Date(s) - 26/10/2021
11:00 am - 12:30 pm

Online-Microsoft Teams
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