Bennett Goldberg

Bennett Goldberg

Office: PHO, Room 920. 617-353-5789
Lab: PHO, Room B11/B21. 3-1712/8-4260
Email:

 

Research Interests:

Selected papers:

  • 02/07/14 Charge Tuning of Nonresonant Magnetoexciton Phonon Interactions in Graphene
  • 11/20/13 Aberration compensation in aplanatic solid immersion lens microscopy
  • 04/29/13 How Graphene Slides: Measurement and Theory of Strain-Dependent Frictional Forces between graphene and SiO2
  • 03/14/12 Single nanoparticle detectors for biological applications
  • 03/21/11 Label-free multiplexed virus detection using spectral reflectance imaging
  • 03/14/11 Chromatic and spherical aberration correction for silicon aplanatic solid immersion lens for fault isolation and photon emission microscopy of integrated circuits
  • 11/21/10 High-Throughput Detection and Sizing of Individual Low-Index Nanoparticles and Viruses for Pathogen Identification
  • 03/21/09 Subsurface microscopy of integrated circuits with angular spectrum and polarization control
  • 07/02/07 Scaling of exciton binding energy with external dielectric function in carbon nanotubes
  • 05/09/07 Screening of Excitons in Single, Suspended Carbon Nanotubes
  • 11/01/06 Tunable Resonant Raman Scattering From Singly Resonant Single Wall Carbon Nanotubes

Bennett B Goldberg (BA'82, MS'84, PhD'87) was born in Boston, Mass. in 1959, and is a life-long Red Sox fan. He received a B.A from Harvard College in 1982, an M.S. and Ph.D. in Physics from Brown University in 1984 and 1987. Following a Bantrell Post-doctoral appointment at the Massachusetts Institute of Technology and the Francis Bitter National Magnet Lab, he joined the physics faculty at Boston University in 1989. Goldberg is a Fellow of the American Physical Society, has been awarded a Sloan Foundation Fellowship and is a recipient of the Presidential Young Investigators Award.

Goldberg is a Professor of Physics, Professor of Electrical and Computer Engineering, Professor of Biomedical Engineering, and Professor of Education. He is a former chair of the Physics Department and his active research interests are in the general area of nano-optics and spectroscopy for hard and soft materials systems. With colleagues, he has studied graphene and other 2D crystals, exploring strain and friction. He has worked in near-field imaging, developed subsurface solid immersion microscopy for Si inspection, and imaging through strongly scattering media. His group is working on novel approaches to subcellular imaging, biosensors and single virus imaging.

Goldberg is Director of Boston University's Center for Nanoscience and Nanobiotechnology, an interdisciplinary center that brings together academic and industrial scientists and engineers in the development of nanotechnology with applications in materials and biomedicine. He is director of BU’s nanomedicine program, bringing engineers and physical scientists together with medical researchers and clinicians.

Goldberg is the inaugural Director of STEM Education Initiatives in the Office of the Provost, working with colleges, departments and faculty in course transformation toward increasing the amount of evidence-based and active-learning in STEM instruction, and in developing and implementing training in teaching and learning for STEM PhD’s and postdocs, our nations future faculty.

 

In the news:

 

Research Descriptions:

High Resolution 4Pi Microscopy

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Confocal fluorescence microscopy has developed into a standard tool in cell biology research; Light can easily penetrate inside the cell and furthermore, a fluorescent dye can be made to interact with specific cellular components, for example attach to an antibody that binds to a cellular protein. The resolution of confocal microscopy is ca 0.5 um laterally and 0.75 um axially.

The axial resolution of a conventional confocal microscope can be improved by a factor of 3-5 in 4Pi microscopy. A 4Pi confocal fluorescence microscope uses two opposing, high numerical aperture objectives, shown in Fig 1. The counter propagating wave fronts of the illumination form interference fringes at the common focal point of the two objectives. Likewise, the collected light is interfered at the detector. This effectively reduces the axial focal volume compared to conventional confocal microscope, illustrated in Fig. 2. The measured point spread function for a fluorescent 100 nm bead is shown in figure 3. The improvement in axial resolution using two objectives (b) compared to standard confocal microscopy (1) can clearly be seen.

We are now combining 4Pi microscopy with an interferometric method we have developed, spectral self-interference fluorescent microscopy. The technique transforms the variation in emission intensity for different path lengths used in fluorescence interferometry to a variation in the intensity for different wavelengths in emission, encoding the high-resolution information in the emission spectrum. Using monolayers of streptavidin, we have demonstrated better than 5nm axial height determination for thin layers of fluorophores and built successful models that accurately fit the data.

Microring Resonator Biosensors

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Microring resonators provide high sensitive label-free optical biosensor platforms. The light coupled into the resonator via a waveguide is confined within the microring cavity due to total internal reflections and high-Q resonant modes (Q~12000) are formed. The positions of these modes depend on the effective index of the resonant structure and thus get shifted when there is a molecular interaction on the surface. This shift can be determined with high precision using our method of detection. We have accomplished to demonstrate biosensing application of the microring resonators by investigating a well studied binding event (Avidin-Biotin complex). The high sensitivities (1.8×10-5 refractive index units) obtained with this method are comparable to commercially available surface plasmon resonance devices. The detection methods that are currently available deliver high sensitivity and specificity; however they fail to provide a clear path to compact optical packaging that will lead to portable devices for field use. Towards this goal, and with the efforts of our interdisciplinary research team and industrial collaborators, we are currently modifying our table-top, fiber-coupled system to develop a cost- efficient, compact integrated biosensor platform.

Numerical Aperture Increasing Lens Microscopy (NAIL)

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Numerical Aperture Increasing Lens (NAIL) microscopy is a far-field subsurface imaging technique that simultaneously enhances the light gathering power and resolution of an optical microscope. When a NAIL is placed on the backside of a sample, its convex surface effectively transforms the NAIL and the planar sample into an integrated solid immersion lens, capable of aberration-free imaging of the structures underneath the substrate. Addition of the NAIL to a standard microscope increases the numerical aperture (NA) by a factor of the square of the optical index n. The NAIL technology has had the greatest impact in the field of optical failure analysis of Si integrated circuits. In silicon, the NA is increased by a factor of 13. Using an optimized confocal microscope, we have already demonstrated a lateral resolution of 230 nm. Recently, we have applied the technique to optical spectroscopy of single quantum dots demonstrating an 8-fold improvement in light collection from a single dot.

Resonant Cavity Imaging Biosensor (RCIB)

The Resonant Cavity Imaging Biosensor (RCIB) detects binding between target biomolecules from a sample and probe biomolecules fixed to a microarray surface with the potential for tens of thousands of simultaneous parallel observation sites. Such ability yields information about the affinity of the biomolecules under test for the molecules on the capturing surface. Information about the affinity between molecules of interest such as particular proteins or DNA strands, yields great benefit to a number of applications in biological research, medical diagnostics, and biohazard detection. Current high-throughput microarray technology requires that the target molecules be labeled with a fluorescent dye. At best, this preparation step adds an acceptably small amount of time and money, but at its worse, can be prohibitively difficult depending on the nature of the application.

RCIB operates label-free without the need to add fluorescent labels or otherwise modify the target molecules in any way. An optical IR beam couples resonantly through a cavity constructed from Bragg mirrors that contains the microarray surface; the wavelength of the IR beam is swept using a tunable IR laser source; and an IR camera monitors cavity transmittance at each pixel, creating a highly parallel signature of transmittance versus wavelength for the microarray surface. This novel technique is enabled by high quality silicon substrates with buried Bragg reflectors previously developed within our group for improved photodetectors. The technique additionally relies on the use of commercial telecommunications hardware that has become readily available in recent years. In an alternative approach for microarray detection, the reflection from the substrate is measured with the varying wavelength. When binding occurs on the surface of the wafer, reflectivity vs. wavelength curve shifts, from which the height information can be extracted. This alternative approach is less sensitive than RCIB, but it draws attention with its simplicity. RCIB improves on existing label-free methods by offering dramatically improved throughput necessary to meet the needs of the microarray user community.