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Silicon nitride and Indium Tin Oxide Nanostructures for dielectrophoretic manipulation of biomolecules

Photo of Dr. Sara Mahshid

Dr. Sara Mahshid

Postdoctoral Fellow, Departments of Physics and of Human Genetic, McGill University, Montreal, Canada

November 27, 2015 14:30 - 16:00

Colonel By Building Room B205, University of Ottawa

Registration not required.


Nanofeatures on semiconductor and metal oxide are used for biomolecule sensing [1,2] and low resolution sequencing of DNA [3,4]. Classical nanochannel-based confinement methods have gained worldwide acceptance for the manipulation and trapping of single DNA molecules. Nanochannel based devices are typically derived on either in pure silicon or silicon dioxide [3,4]. These devices allow highly parallel biomolecular analysis. Despite their widespread use for genomic and physical studies, inherent characteristics, these methods continue to limit the potential for dynamic manipulation and trapping of DNA molecules. They are limited either by sensing resolution or by low concentration of molecules at the nanofeatures.

In order to overcome technical challenges of conventional practices, we propose and demonstrate a novel technological approach, one that utilizes reversible, tunable nanofluidic confinement to immobilize and linearize DNA molecules for single molecule optical analysis- a design based on di-electrophoresis force and ITO patterned electrodes [5]. In this study, the device of design contains a nano-patterned dielectric layer on silicon nitride that sits on top of an indium tin oxide. The second surface contains a uniform transparent conductor. An alternating electric field is then applied between the two surfaces. On the patterned surface, the field is concentrated in the conductive nanofeatures, leading to an enhanced local electric field magnitude. The DEP-force will gently drive the macromolecules into the nanofeatures and then confine them in the features, forcing the molecules to adopt a conformation determined by the local geometry of the patterning, including stretched conformations (in 1D-nanogrooves) and concentrated trapped conformations (quasi 0D cavity patterns).

The ease of fabrication and instrumentation may make our nanostructured device can be a unique point of care instrument for high resolution and highly sensitive biomolecular sensing.


  1. Sara Mahshid, Ch. Li, S. S. Mahshid, M. Askari, A. Dolati, L.Yang, Sh. Luo and Q. Cai, Analyst, 136, 2011, 2322-2329.
  2. Sara Mahshid, Sh. Luo, L. Yang, S. S. Mahshid, M. Askari, A. Dolati and Q. Cai, Journal of Nanoscience and Nanotechnology, 11, 2011, 6668-6675.
  3. D. Berard, F. Michaud, Sara Mahshid, M. J. Ahamed, M.J. McFaul, P. Burebe, R. Sladek, W. Reisner, S. R. Leslie, PNAS (Proceedings of National Academy of Science), 111, 2014, 13295-13300.
  4. Sara Mahshid, Mohammed Jalal Ahamed, Daniel Berard, Susan Amin, Rob Sladek, Sabrina Leslie, Walter Reisner, Lab-on-a-chip, 2015.
  5. Sara Mahshid, Mohammed Jalal Ahamed, Rob Sladek, and Walter Reisner, "Methods and Systems Relating to Dielectrophoretic Manipulation of Molecules", McGill ROI 15117, US patent pending, 2015.

Last updated November 22, 2015

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