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Periods of human civilization are often denoted by a major materials group that emerged during the respective period. There are ample and significant examples in communications, entertainment, information, healthcare, energy, and environment industries to assume that we currently live in a period of sub-micron materials, i.e., materials engineered at the micrometer and nanometer length scales. The timeline in the figure illustrates various periods of civilization. Both high income countries and emerging countries are facing various societal challenges which include a growing demand for clean water, energy and environment, affordable transportation and healthcare, and security of information, built environment and food supply. Further research in the field of materials science and engineering is expected to mitigate these societal challenges and needs. Significant efforts are necessary in (a) using abundant and cost effective materials more widely, (b) ecologically friendly processing of materials, (c) improving the multi-functionality of materials, (d) developing reliable methods and tools to select materials based on full life cycle analysis, (e) recycling materials, and (f) the conservation of materials.
The conventional definition of ‘biomaterial’ is a material intended to interface with biological systems to evaluate, treat, augment, or replace any tissue, organ or function of the human body. Biomaterials have evolved alongside medical devices, and their world market size is estimated to be $30 billion. In general, researchers, educators and students in the biomaterials field limit themselves to medical devices. However, it is to be noted that biomaterials are also used in pharmaceuticals, complimentary medicines and health supplements, biotechnology and biologics, functional foods, fortified foods, and food packaging, cosmetics, and animal medicines and food sectors. There is growing concern on the safety and efficacy aspects of materials used, and national regulatory bodies are catching up with these sectors. Broadening the scope of conventional biomaterials science and engineering to these sectors will benefit the public in terms of higher quality products, and students in terms of wider career options and experience. Hence there is a need to re-cast the field of biomaterials as it is set to grow in the years ahead [1].
Historical experience indicates that global electricity and energy consumption continue to increase despite intermittent economic shocks. The bulk of the need is met from fossil fuels: namely coal, natural gas and oil. Hydro, nuclear, geothermal, biomass, wind, solar, wave and tidal sources contribute less than the desired levels to the overall energy mix and are subject to availability in different countries and regions. Natural gas is less polluting among the fossil fuels, and hence several countries are increasing the share of its use. Moreover with the discovery of new gas fields and new methods of harnessing shale gas, additional supplies of natural gas continue to enter the world market. However there is growing concern for the climate change effects of fossil fuel generated emissions. Capturing and storing emission gases in cost effective and environmentally friendly ways requires significant advancements in catalysts, mineralization, separation, and storage materials.
Hydro and nuclear generated electricity projects are facing public concern regarding their impact on the environment. Geothermal and marine (tidal and wave) energy sources tend to be located away from major energy consumption centers. Long distance electricity transmission is well established; however transmission energy losses are significant. To overcome this challenge, there is a need to further advance super-conducting materials which can perform at the ambient temperature conditions and better insulating materials.
Wind energy and solar energy have gained an increased share of the energy mix with the help of government subsidies, tax breaks, feed-in tariffs, and long term fixed price arrangements. Further advancements in terms of materials and systems design are necessary to lower the high cost of harvesting energy from such sources. Wind and solar energies are intermittent and hence require large energy storage systems which are safe, reliable and cost effective. Some energy storage systems such as re-chargeable batteries require rare earth materials. Developing energy harvesting and storage based on earth and low cost elements is the way forward to further deepen the usage of energy from renewable sources. Smart grids are critical to maximize the potential of renewable energies as well as conventional energies.
Biomass potential is limited by the availability of land mass and concerns of food security and prices. Other promising areas such as waste heat recovery, energy efficiency, energy conservation, smart grids, and hydrogen generation by water splitting require materials advancements in terms of high figure of merit thermoelectric materials [2] superior thermal management materials, visible light operated and stable catalysts, and high performing multi-functional materials.
More than sixty per cent of the world population lives in urban areas. Cities with more than a million people are now common in all regions of the world. The built environment of urban areas must cater to diverse purposes such as residences, business and commercial activities, manufacturing industries, and recreation. Provision of clean water, energy, electricity, food, supplies, transportation, waste disposal, etc., for such large populations will invariably have an impact on the quality of the built environment and in turn on the health of urbanites [3]. Light weight, damage tolerant, energy efficient, eco-friendly materials which reduce the energy envelope of built-up areas and facilitate the removal of pollutants in the environment are desired to improve the quality of life in urban areas. Materials which can filter air, water, and liquids in a more energy efficient manner, and which are tailorable to remove specific pollutants need to be designed and engineered.
The miniaturization of various products in recent years has happened due to advances in tailoring materials at sub-micron length scales. Often, they are not single materials but composites or hybrids of several distinct material phases integrated on several dimensional scales. Different tailored functions such as electron transport, energy storage, sensing, light absorption, light generation, and gas permeability are performed by different material phases. There is growing need to increase the functionalities of materials, while reducing the energy consumption, thereby leading to faster, more reliable, and self-regulating systems. Future multi-functional materials are expected to adapt to the dynamic needs of their intended applications. Scientists and engineers are thinking of new materials which are designed by mimicking nature, and which can sense, self-heal and re-configure in shape, color, and specific functional characteristics should they get damaged or affected while in use. The overarching goal of developing multi-functional materials is to further improve and optimize the overall system performance.
Advancing materials science and engineering in isolation will yield less than desired benefits to society. Pursuing materials advancement integratively with other emerging fields such as nanotechnology, geoscience, astrophysics, neuroscience, stem cells, biomimetics, ubiquitous sensing, cloud computing, quantum computing, algorithms, logics, full life cycle analysis and eco-friendly design is likely to lead to scientific and technological breakthroughs. Innovations based on such materials advancements are likely to improve the quality of life, and positively change the way of life for billions of people. In the years ahead, materials scientists and engineers around the world are well placed to pursue such super-disciplinary efforts involving several emerging areas.
Further reading
[1 ]S. Ramakrishna, Science (2012) http://sciencecareers.sciencemag.org/career_magazine/previous_issues/articles/2012_11_16/caredit.a1200127
[2] H. Alam, S. Ramakrishna, Nano Energy (2012) http://dx.doi.org/10.1016/j.nanoen.2012.10.005
[3] M.M. Khin, A. Sreekumaran Nair, V. Jagadeesh Babu, R. Murugan, S. Ramakrishna, Energy Environ. Sci. (2012) http://dx.doi.org/10.1039/C2EE21818F