Navigation Links
Researchers at Penn add another tool in their directed assembly toolkit
Date:11/12/2013

An interdisciplinary team of University of Pennsylvania researchers has already developed a technique for controlling liquid crystals by means of physical templates and elastic energy, rather than the electromagnetic fields that manipulate them in televisions and computer monitors. They envision using this technique to direct the assembly of other materials, such as nanoparticles.

Now, the Penn team has added another tool to its directed assembly toolkit, developing a new kind of template for rearranging particles and a new set of patterns that can be formed with them.

The team consists of Kathleen Stebe, the School of Engineering and Applied Science's deputy dean for research and professor in Chemical and Biomolecular Engineering; Randall Kamien, professor in the School of Arts and Sciences' Department of Physics and Astronomy; and Shu Yang, professor in Engineering's departments of Materials Science and Engineering and Chemical and Biomolecular Engineering. Members of their labs also contributed to the new study, including lead author Marcello Cavallaro Jr., Mohamed Gharbi, Daniel Beller, Simon Čopar, Zheng Shi and Tobias Baumgart.

Their work was published in the Proceedings of the National Academy of Science.

Crystals are materials that have molecules arrayed in regular three-dimensional patterns; liquid crystals contain some but not all of these patterns, and their molecules can flow around one another and change the direction they face. This behavior allows defects, places on the surface where the molecular orientation of the liquid crystals is disrupted.

Despite their name, such defects are highly desirable. If the location of the defects can be controlled, the change in pattern or orientation can be put to use. In a liquid crystal display, for example, the crystals' orientation in different regions determines which parts of the screen are illuminated.

In an earlier study, the team had used a template consisting of microscopic posts to arrange the defects on the surface of smectic liquid crystals, a class of the material that forms layers. The position, shape and symmetry of the posts allowed the researchers to manipulate the bottom layer of these liquid crystals which in turn generated patterns of defects on the top layer that were orders of magnitude smaller than the original template.

In their new study, the researchers use nematic liquid crystal, which have less long-range order in their patterns but are the kind found in liquid crystal displays.

"These nematic structures are very reconfigurable. That's the basis of why they're good for displays," Stebe said. "Everyone knew that materials can be moved and positioned with electric and magnetic fields, but we're doing it with fields of elastic energy and showing that this technology can be used in assembling materials."

As in their previous experiments, the team started with a template consisting of microscopic posts that was then topped with the liquid crystal. In this experiment, however, instead of a pattern of defects forming only on the surface of the liquid crystal, a ring-shaped defect encircled each of the posts at their midpoints. This ring then acts like another template, directing the arrangement of patterns on the liquid crystal surface, more than 50 microns away.

"With the smectic liquid crystals," Kamien said, "the patterns of defects we could make were closely associated with the corners of the posts. With nematic liquid crystals, we can form these rings, which is a new way to tell what to go where."

"And we're showing," Yang said, "that, whether we use smectic or nematic crystals, we can use a template that directs these surface defect arrays, which can then hold things like colloids, nanoparticles or quantum dots."

Being able to control the spacing and arrangement of these secondary materials could allow for making new types of antennas, sensors or displays. The team's latest study provides a new set of shapes and patterns to work with in the directed assembly approach to making such devices.

"We're building up the toolkit of the different structures we can make via different confinements of these materials," Stebe said. "Once we have our toolkit filled out, it's going to become more readily apparent how we can make these structures dance how we can make them rearrange themselves however we want the next wave of applications will come."


'/>"/>

Contact: Evan Lerner
elerner@upenn.edu
215-573-6604
University of Pennsylvania
Source:Eurekalert  

Related biology technology :

1. York researchers discover important mechanism behind nanoparticle reactivity
2. Researchers discover how retinal neurons claim the best brain connections
3. Researchers measure flow from a nanoscale fluid jet
4. Researchers advance scheme to design seamless integrated circuits etched on graphene
5. Harvard researchers, pharma experts offer recommendations to expand access to clinical trial data
6. Virginia Tech researchers publish study on jellyfish energy consumption that will improve bio-inspired robotic designs for Navy
7. Spanish researchers sequence non-infiltrating bladder cancer exome
8. Researchers discover and treat toxic effects of ALS mutation in neurons made from patients skin cells
9. Researchers advance toward engineering wildly new genome
10. Researchers use nanoparticles to deliver vaccines to lungs
11. UCLA researchers smartphone microscope can detect a single virus, nanoparticles
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Researchers at Penn add another tool in their directed assembly toolkit
(Date:10/11/2017)... and LAGUNA HILLS, Calif. , Oct. ... Cancer Research, London (ICR) and University ... SKY92, SkylineDx,s prognostic tool to risk-stratify patients with multiple myeloma ... MUK nine . The University of Leeds ... partly funded by Myeloma UK, and ICR will perform the ...
(Date:10/10/2017)... ... 2017 , ... San Diego-based team building and cooking events company, Lajollacooks4u, has ... The bold new look is part of a transformation to increase awareness, appeal to ... period. , It will also expand its service offering from its signature gourmet cooking ...
(Date:10/10/2017)... 10, 2017 International research firm Parks Associates announced ... at the TMA 2017 Annual Meeting , October 11 in ... residential home security market and how smart safety and security products impact ... Parks Associates: Smart Home ... "The residential security market has ...
(Date:10/9/2017)... DIEGO , Oct. 9, 2017  BioTech ... biological mechanism by which its ProCell stem cell ... critical limb ischemia.  The Company, demonstrated that treatment ... amount of limbs saved as compared to standard ... the molecule HGF resulted in reduction of therapeutic ...
Breaking Biology Technology:
(Date:3/28/2017)... , March 28, 2017 The ... Hardware (Camera, Monitors, Servers, Storage Devices), Software (Video Analytics, ... Region - Global Forecast to 2022", published by MarketsandMarkets, ... 2016 and is projected to reach USD 75.64 Billion ... and 2022. The base year considered for the study ...
(Date:3/24/2017)... 24, 2017 The Controller General of Immigration from ... Abdulla Algeen have received the prestigious international IAIR Award for the ... Continue Reading ... ... Controller Abdulla Algeen (small picture on the right) have received the IAIR ...
(Date:3/23/2017)... The report "Gesture Recognition and Touchless Sensing Market by Technology (Touch-based ... to 2022", published by MarketsandMarkets, the market is expected to be worth USD ... 2022. Continue Reading ... ... ...
Breaking Biology News(10 mins):