Alumni
The Art and Science of Seeing the Unknown
Spring 2009 Images
The Spring 2009 issue of Engineer, the BU College of Engineering magazine, featured artistic, scientific images from ENG laboratories. More information about the science behind these images is provided here.
Graphene –a one atom thick layer of carbon—rests on silicon oxide on top of silicon. It is possible to see a single layer of graphene because of interference, a familiar phenomenon seen in the rainbow colors of soap bubbles or in a thin oil film on a water puddle. The addition of something as thin as an atomic layer on the oxide shows up as a change in color of the reflected light. This helps researchers locate the graphene for processing and measurements. Under a light microscope the graphene layer (in purple, 50x magnification) can be seen along with 6 patterns for electrodes which have been processed using e-beam lithography. These devices are used to understand the physics of graphene, which may help enable the development of advanced microelectronic devices. (Images courtesy of Associate Professor Anna Swan and graduate researcher Sebastian Remi.)
"Vortices appear almost everywhere in fluids, and they are responsible for many phenomena we would like to understand and control. They behave in many surprising ways -- especially in the oceans and atmosphere. This visualization shows the result of a simulation where a vortex system results in the "splitting" and "remerging" of a core, or central, vortex [blue, near right; red, far right]. A remarkably similar pattern has been seen in the polar vortex, which was split in half in 2002," said Assistant Professor Lorena Barba. (Image (left) credit to the ICSU World Data Center for Remote Sensing of the Atmosphere. Image (right) courtesy of Lorena Barba.)
This surface scan reveals the contours of a computer chip used to perform microelectrophresis, a method of separating fragments of DNA or other large molecules based on size and electric charge. Researchers use specialized computer programs to design the chip's layout and a manufacturing facility then constructs the chip. In the final steps of manufacture, channels are cut into a thin layer of glass overlying the chip's silicon substrate. The image was produced using a Zygo NewView6000 surface mapping interference microscope. The colors indicate the topography of the chip in relation to the interference microscope. Blue and green features are farther away from the microscope and red, closer. The red rectangles on the right and left are electrodes that provide the electrostatic charge to move DNA through solution. (Image area 2 x 2 millimeters.) (Courtesy of Professor Allyn Hubbard).
An artist’s rendering depicts the conversion of a single-color laser beam (entering from right) into an ultra-broadband spectrum of colors (left). The resulting photons are generated as entangled pairs (indicated by white curves), meaning that the arrival times of the two photons are correlated. This process, a nonlinear optical phenomenon called chirped quasi-phase matched optical parametric down conversion, was used for the first time by a team at BU led by Professor Malvin Teich and their colleagues at the Institute of Photonic Sciences (ICFO) in Barcelona and the Ginzton Laboratory at Stanford University. The generation of such entangled light will be useful in applications such as entangled-photon microscopy, which promises improved resolution in the imaging of biological specimens. (Image by ICFO & Digivision, courtesy of M.C. Teich.)
To study the aurora borealis, Professor Joshua Semeter observes it from above and from below. A classic auroral oval image, captured by the NASA IMAGE satellite (right), reveals far UV light from the aurora. The light is produced by electrons precipitating into the atmosphere from space. The colors in the aurora reveal information about the energy of these electrons (which typically exceed 50000 km/s), and the chemical composition of the upper atmosphere. Patterns observed in auroral displays reveal information about the complex plasma physics occurring in the magnetic environment surrounding the Earth.
An image from the ground (left), captured at the same time from a Greenland research facility helps highlight the difference in scale between these two types of image. “The satellite image shows a lot of structure in the auroral oval. There are two concentric bands, the northern band is about 100 kilometers wide, and each band consists of blobs of light, arranged like a string of pearls. The ‘rays’ [in the ground-based photo] are embedded in these pearls and are less than one kilometer across. We don’t fully understand how all this structuring occurs,” said Semeter. (Images courtesy of Josh Semeter.)
Fibronectin, a fiber that lends structure and strength to tissues, (in green and blue on right) may be one of the few tissue types capable of translating mechanical force, such as tension or sound, into chemical signals, ordering other cells to carry out certain tasks. Fluorescent stains reveal how much strain is on the fibers –blue and green indicate an extremely stretched fiber, red and orange reveal relaxation. As the strain changes, fibronectin sends chemical signals to other cells such as fibroblasts (purple and green, on left). These fibroblasts are stretched along a skeleton of fibronectin (black vertical and horizontal lines, on left). "You use the response of these cells as an indication of the altered function of the fibronectin fibers," said Assistant Professor Michael Smith (BME). He used a laser scanning confocal microscope to capture these 250 micrometer square images. A false color scale is added with computer software to interpret the intensity of the fluorescence and help calculate the exact degree of tension on the fibers. (Images courtesy of Michael Smith.)
Viruses accumulate as they are grabbed by a virus-specific antibody anchored on a platform of gold. An Atomic Force Microscope measures the height profile, the topography of the viral pile-up to gauge how many have stuck. Red indicates the baseline platform and the color scale progresses toward yellow (50 nanometers tall). Assistant Professor Hatice Altug’s (ECE) research group plans to eventually incorporate an array of these virus detectors into a nanostructure that can capture and identify many different types of virus. The scan sizes (left to right) are 16 micrometers, 30 micrometers and 60 micrometers. (Images courtesy of Hatice Altug.)
The members of Associate Professor Jerome Mertz’s (BME) laboratory develop their own microscopy techniques for biological imaging. Here, they test the capabilities of a homemade second-harmonic generation microscope by examining an area about 300 microns across, revealing a pattern of muscle fibers attached to the sclera –the white of an eye (left, colors have been altered). Another home-built device, a two-photon microscope with a 20X 0.95 N.A. Olympus objective was used to capture nerve activity, with the help of green fluorescent protein to highlight the inhibitory neurons and a blue fluorescent dye to reveal the neurons' activity. “I am studying seizures and using these data I will try to better understand what goes wrong in the dynamics of a neural circuit that leads to a seizure,” said graduate student Kyle Lillis. The image area (far right) is 750 x 550 microns.(Images courtesy of Jerome Mertz and Kyle Lillis.)
Silicon nitride nanopillars containing light emitting silicon nanocrystals are sprinkled across a silicon chip, forming an aperiodic array --a deterministic two-dimensional pattern without translational symmetry. This image from the laboratory of Assistant Professor Luca Dal Negro (ECE) shows the Rudin-Shapiro pattern. Each pillar shown in this Scanning Electron Microscopy image is about 2 microns tall and 800 nanometers in diameter. Color added. (Image courtesy of Luca Dal Negro.)
A landscape of red, orange and yellow is actually a staircase of gold – Associate Professor Kamil Ekinci’s research group has developed a specialized version of a scanning tunneling microscope with resolution on the scale of atoms. One way to test its ability to perform as well as, or better than, a traditional STM is to cut one atom thick stairs into a sheet of gold. The black band (far left image) is the bottom step, and the dark red, orange, and yellow bands each represent one-atom steps up. (Image courtesy of Kamil Ekinci and graduate student Utku Kemiktarak.)
These 10 micrometer-tall pillars of soft polymer material self-assemble, leaning towards each other (left, color added). Associate Professor Xin Zhang’s research group explores polymer fabrication techniques, making pillars of many different shapes and sizes for different applications. Pillars similar to those in this Scanning Electron Microscope image can be used to detect forces occurring within a cell, by setting the cell on top of the pillars. Zhang's laboratory explores the fabrication and properties of many types of metamaterials, materials not normally occuring in nature (below). (Images courtesy of Xin Zhang.)
When a bone is allowed to bend during healing from a break (top), rather than being held immobile (bottom), a different type of recovery occurs. More cartilage forms around the break, indicating that mechanical cues in the microenvironment of healing tissues can direct whether bone or cartilage forms. These types of experiments can be used to identify ways of promoting cartilage formation in damaged or diseased joints. These three-dimensional images were assembled from series of two-dimensional histology sections, and then digitized using visualization software. The 3-D false color images allow Assistant Professor Elise Morgan to quickly see different types of tissue and to quantify the volume of each. (Image courtesy of Elise Morgan.)
