Visiting Fellowship for Professor Bhattacharya - new materials and their implementation for micro mechanics.

Lead Research Organisation: University of Cambridge
Department Name: Physics


Bhattacharya studies the link between the microscopic structure of materials and its macroscopic properties and seeks to use that understanding to guide the development of new materials. Every materials has structural features on a variety of scales and the properties that we experience are a sum-total of the interaction between all these scales. he is specifically interested in active materials, solids that possess unusual coupling between mechanical, thermal, electrical, optical and other properties so that one property can be controlled using another. These include piezoelectric materials that are central to any ultra-sonic device and shape-memory alloys that remember their shape and are used for a number of medical devices. Bhattacharya will visit Cambridge to collaborate with researchers with overlapping interest and complementary expertise on a variety of projects involving active materials and nano-systems. His expertise will bridge the gap from novel materials to macroscopic response. He will lecture and give tutorial seminars on new theoretical methods for the analysis of materials, on active materials and emerging ideas for nano-systems where the materials acts as the machine.


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Bhattacharya K (2009) Stress-Induced Phase Transformations in Shape-Memory Polycrystals in Archive for Rational Mechanics and Analysis

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Biggins J (2009) Textured deformations in liquid crystal elastomers in Liquid Crystals

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Biggins J (2012) Elasticity of polydomain liquid crystal elastomers in Journal of the Mechanics and Physics of Solids

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Biggins JS (2009) Supersoft elasticity in polydomain nematic elastomers. in Physical review letters

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Biggins JS (2009) Characterization of soft stripe-domain deformations in Sm-C and Sm-C* liquid-crystal elastomers. in Physical review. E, Statistical, nonlinear, and soft matter physics

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Dondl P (2009) A Sharp Interface Model for the Propagation of Martensitic Phase Boundaries in Archive for Rational Mechanics and Analysis

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Modes C (2010) Gaussian curvature from flat elastica sheets in Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

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Modes CD (2010) Disclination-mediated thermo-optical response in nematic glass sheets. in Physical review. E, Statistical, nonlinear, and soft matter physics

Description 1. The collaboration under this grant discovered that polydomain liquid crystalline rubber, depending on its genesis, can deform with extremely low energy cost. This was known from the research of this group to hold for delicately made monodomains, but exploiting this unusual property is hard because of the skill needed to make samples. Polydomains are simple to make. The result was highly counterintuitive, but was found independently in experiments done in Japan.

2. Another revolutionary property was discovered - that with the application of light or heat, the Gaussian (intrinsic) curvature of initially flat sheets could be changed. The problem is well-known to map makers or wrappers of presents! How can you wrap a foot ball (a sphere, that is a shape with intrinsic curvature) with a flat sheet of paper without folds, creases, crumpling? It cannot be done. Liquid crystalline solid sheets with topological defects and/or gradients in their nematic fields were shown theoretically to react to heat or light by developing Gaussian curvature - a totally new departure.
Exploitation Route 1. The remarkable property of extension without energy cost (ie with minimal tension developed) is lost on heating or illumination (in the case of photo-elastomers). If the material has been thus stretched and then is illuminated, then it has the strong need to contract to eliminate the tension built up. In doing so, it can be harnessed to do work, thereby converting light or heat to mechanical (eg electrical) energy. A sequence of proposals for energy harvesting devices has been made as a consequence of this grant.

2. Change in curvature is developed in response to light in order to avoid stretches that would develop if the sample remained flat. These are typically nematic photo-glasses. On removal of the light source, the Gaussian curvature must be eliminated (the sample returned to the flat state) in order to avoid stretches. This means that work can be done. Applications to health care devices (micro-fluidics components) have been pursued by collaborators in Holland (TU Eindhoven and Philips Eindhoven). The principle is that for instance fluids could be pumped by the changes in shape; the stimulus being light is very attractive since light is easy to deliver compared with heat or electricity, and is very fast.
Adaptive shapes for drag reduction are another possibility and discussions are being held with aerospace engineers (for instance in Bhattacharya's home institution, Cal Tech).
Sectors Aerospace, Defence and Marine,Energy,Healthcare

Description Research groups in the USA and Japan have made solar-powered engines using the principles of nematic photo-elastomer response predicted and modeled under this grant. Engineers have done finite element modeling of Gaussian curvature creation and its exploitation in device geometries. Collaborators in Eindhoven, Zaragossa and the USAF Wright Patterson research Lab have made sheets with suitable topological defects or spatially varying patterns in their nematic fields. These have been demonstrated to show Gaussian curvature as predicted. Groups (Eindhoven & Zaragossa) interested in Heath Care Devices have made sheets with patterns such that on illumination arrays of nano slits open up, the extent of which is determined by light intensity. These will be light-driven sieves and clearable filters.
First Year Of Impact 2011
Sector Energy,Healthcare
Impact Types Economic