Honors & Awards


  • Teaching Fellowship, Stanford University (Sept. 2019)
  • Centennial Teaching Assistant Award Winner, Stanford University (June, 2019)
  • Robert S. Hilbert Memorial Optical Design Competition Winner, Synopsys (Aug, 2018)
  • James F. Gibbons Outstanding Student Teaching Award in Electrical Engineering, Stanford University (June 18, 2017)
  • Departmental Fellowship, Department of Electrical Engineering, Stanford University (Sept. 2014)

Education & Certifications


  • MS, Bangladesh University of Engineering and Technology, Electrical and Electronic Engineering (2011)
  • BS, Bangladesh University of Engineering and Technology, Electrical and Electronic Engineering (2009)

Stanford Advisors


Service, Volunteer and Community Work


  • Member, Technical Committee for evaluating radiation hazards from commercial roof-top cellphone towers in Bangladesh, Bangladesh Telecommunication Regulatory Commission (BTRC) and Bangladesh University of Engineering and Technology (2013)

    Location

    Dhaka, Bangladesh

  • Guest Lecturer, National Institute of Mass Communication (2011 - 2012)

    Location

    Dhaka, Bangladesh

  • Treasurer, IEEE Bangladesh Section (January 2012 - December 2012)

    Location

    Bangladesh

  • Member, Organizing Committee, International Conference on Electrical and Computer Engineering (ICECE) (2012)

    Location

    Dhaka, Bangladesh

Personal Interests


Amateur Radio (License: Amateur extra, Call sign: AE6AZ)
Chess
Reading
Astronomy

Current Research and Scholarly Interests


My research focuses on trapping and controlled manipulation of sub-micron sized particles. The work included modeling, fabrication and testing of chips that employ optical forces and/or dielectrophoretic forces to trap and transport nanoparticles. Our goal is to develop lab-on-a-chip systems for biomedical and chemical applications.

Projects


  • Plasmonic trapping and manipulation of nanoparticles, Stanford University (9/1/2014 - Present)

    Design, fabrication and testing of C-shaped plasmonic structures for trapping and manipulation of dielectric and metallic nanoparticles.

    Location

    Stanford, CA

    Collaborators

    • Punnag Padhy, Ph.D. Student in Electrical Engineering, admitted Summer 2016, School of Engineering
    • Paul Hansen, Phys Sci Res Assoc, Academic Units, Academic Units
    • Lambertus Hesselink, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University
  • Dielectrophoretic trapping, Stanford University (August 1, 2015 - Present)

    Selective trapping and manipulation of dielectric particles using dielectrophoresis

    Location

    Stanford, CA

    Collaborators

    • Punnag Padhy, Ph.D. Student in Electrical Engineering, admitted Summer 2016, School of Engineering
    • Lambertus Hesselink, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University
  • Adjoint optimization, Stanford University (March 1, 2016 - December 1, 2016)

    Application of discrete and continuous adjoint optimization techniques in practical engineering problems

    Location

    Stanford, CA

    Collaborators

    • Lars Neustock, Ph.D. Student in Electrical Engineering, admitted Autumn 2015, School of Engineering
    • Paul Hansen, Phys Sci Res Assoc, Academic Units, Academic Units
    • Lambertus Hesselink, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University
  • Microfluidic system design for droplet generation, Stanford University (June 1, 2017 - Present)

    We are developing a microfluidic system that can generate droplets with diameters of a few micron.

    Location

    Stanford, CA

    Collaborators

    • Punnag Padhy, Ph.D. Student in Electrical Engineering, admitted Summer 2016, School of Engineering
    • Maha Yusuf, Ph.D. Student in Chemical Engineering, admitted Autumn 2015, School of Engineering
    • Lambertus Hesselink, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University
  • On chip system for small volume biochemistry, Stanford University (June 1, 2017 - Present)

    A lab-on-a-chip microfluidic system capable of trapping and manipulating particles will be developed to perform small scale chemical reactions for bio applications.

    Location

    Stanford, CA

    Collaborators

    • Punnag Padhy, Ph.D. Student in Electrical Engineering, admitted Summer 2016, School of Engineering
    • Maha Yusuf, Ph.D. Student in Chemical Engineering, admitted Autumn 2015, School of Engineering
    • Lambertus Hesselink, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University

Lab Affiliations


2019-20 Courses


Work Experience


  • Research Assistant, Stanford University (June 22, 2015 - Present)

    Hesselink Group

    Location

    Stanford, CA 94305

  • Teaching Assistant, Stanford University (January 9, 2017 - March 17, 2017)

    Teaching Assistant of the course EE 134

    Location

    Stanford, CA 94305

All Publications


  • Solenoidal optical forces from a plasmonic Archimedean spiral PHYSICAL REVIEW A Zaman, M., Padhy, P., Hesselink, L. 2019; 100 (1)
  • Fokker-Planck analysis of optical near-field traps. Scientific reports Zaman, M. A., Padhy, P., Hesselink, L. 2019; 9 (1): 9557

    Abstract

    The motion of a nanoparticle in the vicinity of a near-field optical trap is modeled using the Fokker-Planck equation. A plasmonic C-shaped engraving on a gold film is considered as the optical trap. The time evolution of the position probability density of the nanoparticle is calculated to analyze the trapping dynamics. A spatially varying diffusion tensor is used in the formulation to take into account the hydrodynamic interactions. The steady-state position distribution obtained from the Fokker-Planck equation is compared with experimental results and found to be in good agreement. Computational cost of the proposed method is compared with the conventionally used Langevin equation based approach. The proposed method is found to be computationally efficient (requiring 35 times less computation time) and scalable to more complex lab-on-a-chip systems.

    View details for DOI 10.1038/s41598-019-45609-x

    View details for PubMedID 31266994

  • Near-field optical trapping in a non-conservative force field. Scientific reports Zaman, M. A., Padhy, P., Hesselink, L. 2019; 9 (1): 649

    Abstract

    The force-field generated by a near-field optical trap is analyzed. A C-shaped engraving on a gold film is considered as the trap. By separating out the conservative component and the solenoidal component of the force-field using Helmholtz-Hodge decomposition, it was found that the force is non-conservative. Conventional method of calculating the optical potential from the force-field is shown to be inaccurate when the trapping force is not purely conservative. An alternative method is presented to accurately estimate the potential. The positional statistics of a trapped nanoparticle in this non-conservative field is calculated. A model is proposed that relates the position distribution to the conservative component of the force. The model is found to be consistent with numerical and experimental results. In order to show the generality of the approach, the same analysis is repeated for a plasmonic trap consisting of a gold nanopillar. Similar consistency is observed for this structure as well.

    View details for PubMedID 30679539

  • Extracting the potential-well of a near-field optical trap using the Helmholtz-Hodge decomposition APPLIED PHYSICS LETTERS Zaman, M., Padhy, P., Hansen, P. C., Hesselink, L. 2018; 112 (9)

    View details for DOI 10.1063/1.5016810

    View details for Web of Science ID 000427022500003

  • Capturing range of a near-field optical trap PHYSICAL REVIEW A Zaman, M., Padhy, P., Hesselink, L. 2017; 96 (4)
  • Dielectrophoresis-assisted plasmonic trapping of dielectric nanoparticles PHYSICAL REVIEW A Zaman, M. A., Padhy, P., Hansen, P. C., Hesselink, L. 2017; 95 (2)
  • Photonic radiative cooler optimization using Taguchi's method INTERNATIONAL JOURNAL OF THERMAL SCIENCES Zaman, M. 2019; 144: 21–26
  • Design of a high numerical aperture achromatic objective lens for endomicroscopy OPTICAL ENGINEERING Zaman, M., Buyukalp, Y. 2019; 58 (7)
  • In-plane near-field optical barrier on a chip OPTICS LETTERS Padhy, P., Zaman, M., Hesselink, L. 2019; 44 (8): 2061–64

    Abstract

    Nanoparticles trapped on resonant near-field structures engraved on a metallic substrate experience forces due to the engravings, as well as the image-like interaction with the substrate. In the case of normally incident optical excitation, the force due to the substrate is solely perpendicular to its surface. Numerical simulations are presented to demonstrate that under the combined influence of the aforementioned forces, a plasmonic nanoparticle can be repelled from the engraving along the substrate, while attracting it towards the substrate along its normal. This behavior can be achieved over a range of excitation wavelengths of the short wavelength mode of the coupled particle-substrate-trap system. To the best of our knowledge, this is the first illustration of an in-plane near-field optical barrier on a chip. The barrier is stable against resistive heating of the nanoparticle, as well as the induced non-isothermal flow. The wavelength-dependent switch between the proposed in-plane potential barrier and the stable potential well can pave the way for the gated transport of single nanoparticles, while holding them bound to the chip.

    View details for DOI 10.1364/OL.44.002061

    View details for Web of Science ID 000464601900046

    View details for PubMedID 30985811

  • A semi-analytical model of a near-field optical trapping potential well JOURNAL OF APPLIED PHYSICS Zaman, M., Padhy, P., Hesselink, L. 2017; 122 (16)

    View details for DOI 10.1063/1.5000269

    View details for Web of Science ID 000414225500001

  • On the substrate contribution to the back action trapping of plasmonic nanoparticles on resonant near-field traps in plasmonic films OPTICS EXPRESS Padhy, P., Zaman, M., Hansen, P., Hesselink, L. 2017; 25 (21): 26198–214

    Abstract

    Nanoparticles trapped on resonant near-field apertures/engravings carved in plasmonic films experience optical forces due to the steep intensity gradient field of the aperture/engraving as well as the image like interaction with the substrate. For non-resonant nanoparticles the contribution of the substrate interaction to the trapping force in the vicinity of the trap (aperture/engraving) mode is negligible. But, in the case of plasmonic nanoparticles, the contribution of the substrate interaction to the low frequency stable trapping mode of the coupled particle-trap system increases as their resonance is tuned to the trap resonance. The strength of the substrate interaction depends on the height of the nanoparticle above the substrate. As a result, a difference in back action mechanism arises for nanoparticle displacements perpendicular to the substrate and along it. For nanoparticle displacements perpendicular to the substrate, the self induced back action component of the trap force arises due to changing interaction with the substrate as well as the trap. On the other hand, for displacements along the substrate, it arises solely due to the changing interaction with the trap. This additional contribution of the substrate leads to more pronounced back action. Numerical simulation results are presented to illustrate these effects using a bowtie engraving as the near-field trap and a nanorod as the trapped plasmonic nanoparticle. The substrate's role may be important in manipulation of plasmonic nanoparticles between successive traps of on-chip optical conveyor belts, because they have to traverse over regions of bare substrate while being handed off between these traps.

    View details for DOI 10.1364/OE.25.026198

    View details for Web of Science ID 000413103300123

    View details for PubMedID 29041280

  • Adjoint method for estimating Jiles-Atherton hysteresis model parameters JOURNAL OF APPLIED PHYSICS Zaman, M. A., Hansen, P. C., Neustock, L. T., Padhy, P., Hesselink, L. 2016; 120 (9)

    View details for DOI 10.1063/1.4962153

    View details for Web of Science ID 000383978100014

  • Optimization of multilayer antireflection coating for photovoltaic applications OPTICS AND LASER TECHNOLOGY Sikder, U., Zaman, M. A. 2016; 79: 88-94
  • Application of Taguchi's method to optimize fiber Raman amplifier OPTICAL ENGINEERING Zaman, M. A. 2016; 55 (4)
  • Bouc-Wen hysteresis model identification using Modified Firefly Algorithm JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Zaman, M. A., Sikder, U. 2015; 395: 229-233