The goal of CRISP professional development workshops is to improve the quality and diversity of STEM education for science teachers in neighboring urban school districts. CRISP offers inquiry-based workshops which utilize CRISP specialized research facilities to emphasize the interdisciplinary nature of materials science and nanotechnology. Workshops have been offered to more than 100 participants to date.
The unique properties of transition metal oxides allow electrons to be manipulated in new ways. At CRISP, we have created an oxide device that enables a gas of electrons to be expanded or compressed with an applied electric field. The expansion or compression of the gas modulates the speed of moving electrons. The change in the speed of the electrons could be utilized in high speed transistors.
Many species of birds have feathers with colors that are the result
of light scattering from a disordered arrangement of nanoscale air
spheres. The feathers appear to be the same color from every angle.
Inspired by these beautiful feathers, we design structures of polymer
nanoparticles that produce color the same way. This is a new way to make
color from nanostructures and could be useful for textiles, coatings,
and cosmetics.
A multi-partner collaborative effort has focused on understanding semiconductor-oxide interfaces. This involves atomic layer precision in synthesis of the structures, correlating the structure and electronic properties using first principles, and obtaining subatomic resolution of structures from synchrotron x-ray diffraction a the Advanced Photon Source (Argonne National Laboratory) and electron micrsocopy (Brookhaven National Laboratory). The outcomes of these studies are critical for the design of ferroelectric field effect transistors.
Transition metal oxides exhibit many properties that can be harnessed in novel devices. For example, an epitaxial ferroelectric on silicon enables a nonvolatile transistor that remembers its state without continuous power consumption. A critical question is how the oxide/silicon interface affects the oxide functionality.
The vivid, angle-dependent structural colors of some butterfly wing-scales are produced by light scattering from complex three-dimensional nanoscale structures. With intricate structural knowledge from synchrotron small angle x-ray scattering (SAXS), we hypothesize that the butterfly nanostructures develop by the self-organizing kinetics of cellular membranes, as with soft matter systems such as a soap film spanning a wire contour.
Optical properties of nanomaterials are at the basis of a host
of new technology and prototypes, including sensors, computing devices, and
enhancing substrates for spectroscopy, yet fundamental understanding on how to
tune such properties is just emerging. Researchers at Northwestern University
have previously developed a method to accurately correlate the structure and
properties of nanoparticles at the single particle
level. This technique has now been used in a high throughput fashion to observe
and quantify how the optical response of nanocubes is
affected by size, composition and environment.
When a negatively
charged, high molecular weight polymer (hyaluronic acid) is mixed with a positively charged peptide-based,
self-assembling molecule, a membrane is instantaneously formed at the interface
of the two solutions. These closed membranes (sacs) have a complex hierarchical
structure which presents a unique challenge in quantifying its mechanical
properties. Membrane inflation and osmotic swelling techniques have been used
to quantitatively characterize the membrane properties. These findings will be
essential for tailoring the membrane characteristics for specific future
applications.
Molecular
semiconductors are important materials for technology applications, such as
solar cells. Current research focuses on how to organize molecules at interfaces for more efficient energy
conversion. Maryland MRSEC researchers
and NIST collaborators recently showed
how the arrangement of molecules at a molecular junction impacts energy
conversion. Ultrafast electron transfer takes place when electron-donating CuPc charge transfer, leading to more
efficient devices molecules “stand up”
on their electron-accepting C60 neighbors. Such oriented molecular interfaces
enhance.
Hydrogels undergo volume changes when immersed in water, the degree of which is determined by the network chemical composition and crosslinking. When a hydrogel is attached to a rigid substrate, it swells preferentially perpendicular to the substrate, even though the initial gel was crosslinked homogeneously. This effect arises because the top layer has more freedom to expand. When the osmotic pressure is large enough, the outer surface buckles, resulting in the formation of a surface topography patterns. However, the nonlinear nature of the gel swelling and lack of the control on osmotic pressure make it challenging to control the long-range order and morphology of the final patterns. By introducing crosslinking gradient along the film thickness in poly(2-hydroxylethyl methacrylate) (PHEMA) gels, we are able to fine-tune the network modulus profile, leading to better control of the spontaneous formation of a wide range of surface patterns. Patterns range from highly ordered hexagonal structures to peanut shapes to lamellar and random worm-like structures. We have applied this patterning scheme to create a diverse range of hydrogels for exploration of ideal morphologies for tissue engineering scaffolds. Specifically, it allows us to look at living networks, such as cells, and identify the molecular mechanisms that cells use for mechanosensing.
When a negatively
charged, high molecular weight polymer (hyaluronic acid) is mixed with a positively charged peptide-based,
self-assembling molecule, a membrane is instantaneously formed at the interface
of the two solutions. These closed membranes (sacs) have a complex hierarchical
structure which presents a unique challenge in quantifying its mechanical
properties. Membrane inflation and osmotic swelling techniques have been used
to quantitatively characterize the membrane properties. These findings will be
essential for tailoring the membrane characteristics for specific future
applications.
Hydrogels undergo volume changes when immersed in water, the degree of which is determined by the network chemical composition and crosslinking. When a hydrogel is attached to a rigid substrate, it swells preferentially perpendicular to the substrate, even though the initial gel was crosslinked homogeneously. This effect arises because the top layer has more freedom to expand. When the osmotic pressure is large enough, the outer surface buckles, resulting in the formation of a surface topography patterns. However, the nonlinear nature of the gel swelling and lack of the control on osmotic pressure make it challenging to control the long-range order and morphology of the final patterns. By introducing crosslinking gradient along the film thickness in poly(2-hydroxylethyl methacrylate) (PHEMA) gels, we are able to fine-tune the network modulus profile, leading to better control of the spontaneous formation of a wide range of surface patterns. Patterns range from highly ordered hexagonal structures to peanut shapes to lamellar and random worm-like structures. We have applied this patterning scheme to create a diverse range of hydrogels for exploration of ideal morphologies for tissue engineering scaffolds. Specifically, it allows us to look at living networks, such as cells, and identify the molecular mechanisms that cells use for mechanosensing.