Navigation Links
Smart materials get SMARTer
Date:7/11/2012

Cambridge, Mass. July 11, 2012 Living organisms have developed sophisticated ways to maintain stability in a changing environment, withstanding fluctuations in temperature, pH, pressure, and the presence or absence of crucial molecules. The integration of similar features in artificial materials, however, has remained a challengeuntil now.

In the July 12 issue of Nature, a Harvard-led team of engineers presented a strategy for building self-thermoregulating nanomaterials that can, in principle, be tailored to maintain a set pH, pressure, or just about any other desired parameter by meeting the environmental changes with a compensatory chemical feedback response.

Called SMARTS (Self-regulated Mechano-chemical Adaptively Reconfigurable Tunable System), this newly developed materials platform offers a customizable way to autonomously turn chemical reactions on and off and reproduce the type of dynamic self-powered feedback loops found in biological systems.

The advance represents a step toward more intelligent and efficient medical implants and even dynamic buildings that could respond to the weather for increased energy efficiency. The researchers also expect that their methodology could have considerable potential for translation into areas such as robotics, computing, and healthcare.

Structurally, SMARTS resembles a microscopic toothbrush, with bristles that can stand up or lie down, making and breaking contact with a layer containing chemical 'nutrients'.

"Think about how goosebumps form on your skin," explains lead author Joanna Aizenberg, Amy Smith Berylson Professor of Materials Science at the Harvard School of Engineering and Applied Sciences (SEAS) and a Core Faculty Member at the Wyss Institute for Biologically Inspired Engineering at Harvard. "When it is cold out, tiny muscles at the base of each hair on your arm cause the hairs to stand up in an insulating layer. As your skin warms up, the muscles contract and the hairs lie back down to keep you from overheating. SMARTS works in a similar way."

Natural materials like skin are incredibly dynamic and can maintain control in a wide range of environments through self-regulation. By contrast, synthetic materials cannot easily replicate homeostasis. Even the "smartest" materialslike eyeglasses that darken in sunlight, or a piezoelectric sensor that converts the vibrations of an acoustic guitar into a digital audio signaltypically only react to one specific environmental stimulus and do not self-regulate.

"By building dynamic feedback loops into SMARTS from the bottom up, we were able to integrate the desired regulatory features into the material itself," says co-lead author Ximin He, a postdoctoral fellow in the Aizenberg lab. "Whether it is the pH level, temperature, wetness, pressure, or something else, SMARTS can be designed to directly sense and modulate the desired stimulus using no external power or complex machinery, giving us a conceptually new robust platform that is customizable, reversible, and remarkably precise."

To demonstrate SMARTS, He, Aizenberg, and the team chose temperature as the stimulus and embedded an array of tiny nanofibers, akin to little hairs, in a layer of hydrogel. The hydrogel, similar to a muscle, can either swell or contract in response to changes in the temperature. (See movie.)

When the temperature drops, the gel swells, and the hairs stand upright and make contact with the 'nutrient' layer; when it warms up, the gel contracts, and the hairs lie down. The key aspect is that molecular catalysts placed on the tips of the nanofibers can trigger heat-generating chemical reactions in the 'nutrient' layer.

"The bilayer system effectively creates a self-regulated on-and-off switch controlled by the motion of the hairs, turning the reaction on and generating heat when it is cold. Once the temperature has achieved a pre-determined level, the hydrogel contracts, causing the hairs to lie down, interrupting further generation of heat. When it cools again below the set-point the cycle restarts autonomously. It's homeostasis, right down at the materials level," says Aizenberg.

The researchers anticipate that with further refinement the technique could be integrated into materials for medical implants to help stabilize bodily functions, perhaps sensing and adjusting the level of glucose or carbon dioxide in the blood. Furthermore, the oscillating mechanical motion of the hairs could be put to work or used for propulsion, like cilia in a living organism.

"In principle, you can turn anythingheat, light, mechanical pressureinto a chemical signal within the gel. Likewise, the reactions triggered by the moving hairs can produce many different types of compensatory responses. By matching signals and responses, we can, in principle, create a wide variety of self-regulating feedback loops," adds He.

Beside its technological applications, SMARTS is also an ideal "laboratory" to study the fundamental properties of biological and chemical systems, such as how living systems are able to so efficiently convert between chemical and mechanical processes.

"We found a new way to think about materials and created a fascinating system to look at some fundamental, deep questions about how living things maintain a stable state," says Aizenberg.


'/>"/>
Contact: Michael Patrick Rutter
mrutter@seas.harvard.edu
617-496-3815
Harvard University
Source:Eurekalert  

Related biology technology :

1. Squid and zebrafish cells inspire camouflaging smart materials
2. AMRI Launches SMARTSOURCING™ For Contract Manufacturing and Research Services
3. Smart, self-healing hydrogels open far-reaching possibilities in medicine, engineering
4. Netsmart Selects Overland Park, Kansas, for New Office
5. Netsmart Clients to Receive Nearly $2 Million in Meaningful Use EHR Incentive Payments
6. Shape-shifting materials are goal of new nanotechnology project
7. Unprecedented subatomic details of exotic ferroelectric nanomaterials
8. First 3-D nanoscale optical cavities from metamaterials
9. Penn researchers study of phase change materials could lead to better computer memory
10. ATCC Announces Agreement with Life Technologies Corporation to Sell and Distribute Green Fluorescent Protein (GFP)-based Materials
11. Metamaterials, quantum dots show promise for new technologies
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Smart materials get SMARTer
(Date:10/12/2017)... ... October 12, 2017 , ... ... Lithuania, announced today that they have entered into a multiyear collaboration to identify ... CRISPR researchers with additional tools for gene editing across all applications. , Under ...
(Date:10/12/2017)... , ... October 12, 2017 , ... ... Wound Market with the addition of its newest module, US Hemostats & Sealants. ... for thrombin hemostats, absorbable hemostats, fibrin sealants, synthetic sealants and biologic sealants used ...
(Date:10/12/2017)... ... October 12, 2017 , ... ... Rosalind™, the first-ever genomics analysis platform specifically designed for life science researchers ... honor of pioneering researcher Rosalind Franklin, who made a major contribution to ...
(Date:10/11/2017)... ... October 11, 2017 , ... ... in its endogenous context, enabling overexpression experiments and avoiding the use of exogenous ... RNA guides is transformative for performing systematic gain-of-function studies. , This complement ...
Breaking Biology Technology:
(Date:7/20/2017)... Delta (NYSE: DAL ) customers now can use fingerprints instead ... National Airport (DCA). ... Delta launches biometrics to board aircraft at Reagan Washington National Airport ... Delta,s biometric boarding pass experience that launched in ... the boarding process to allow eligible Delta SkyMiles Members who are enrolled ...
(Date:5/23/2017)... the first robotic gym for the rehabilitation and functional motor sense evaluation ... Genoa, Italy . The first 30 robots will be available from ... . The technology was developed and patented at the IIT laboratories ... Technology thanks to a 10 million euro investment from entrepreneur Sergio Dompè. ... ...
(Date:4/24/2017)... , April 24, 2017 ... and partner with  Identity Strategy Partners, LLP (IdSP) ... "With or without President Trump,s March 6, 2017 ... Terrorist Entry , refugee vetting can be instilled with ... resettlement. (Right now, all refugee applications are suspended ...
Breaking Biology News(10 mins):