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“Smaller-sized components have much larger surface area-to-volume ratios as compared to bigger components and hence, surface forces and surface properties determine their performance and durability within the machines in which they run – this is especially so in miniature machines with components several micrometers in dimension.”
– Dr Sujeet Sinha, Department of Mechanical Engineering on the importance of lubrication for micro machines. |
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Into the age of mighty micro machines
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| HIGH PERFORMANCE: Team working on lubrication of MEMS, Dr Sujeet K Sinha (seated, right) with two of his collaborators, Dr Choo Jian Huei (on his left) and Dr Nalam Satyanarayarana (standing, 3rd from right), and his motivated team of students. |
GIVING micro machines the added oomph and power is a team of researchers at the NUS Department of Mechanical Engineering led by Dr Sujeet Sinha. Their research project, Biologically-inspired Design, Nano-Fabrication and Nano-Lubrication of MEMS, NEMS, and Micro-Mechanical Devices has garnered funding from the National Research Foundation (NRF)’s Competitive Research Programme Funding Scheme that provides up to $10 million over three to five years period. Their project was one of the four research programmes to have won the grant in NRF’s second call for applicants under the scheme.
Elaborating on his research, Dr Sinha said that as machines become smaller and smaller with the help of nanotechnology, the surfaces of mechanical components would play a crucial role in affecting performance.
“Smaller-sized components have much larger surface area-to-volume ratios as compared to bigger components and hence, surface forces and surface properties determine their performance and durability within the machines in which they run – this is especially so in miniature machines with components several micrometers in dimension,” he said.
Dr Sinha has always been interested in inventing new coatings and surface modification techniques using polymeric systems for micro/macro machines and studying biological materials for surface related applications. He has published more than 100 articles in international journals and conference proceedings.
The success of the next industrial revolution in the area of micro-electro-mechanical systems (MEMS), nano-electro-mechanical systems (NEMS) and other small devices such as those used in medical applications -- and possibly in future clean energy generation -- would crucially depend on the ingenious design of new surfaces.
“Nature has provided us with many examples where surfaces have been tailored to perform specific roles in a wide range of flora and fauna. We aim to adopt Nature’s solutions to design surfaces with unique texturing, chemical modifications and coatings to be applied in nano machines to attain specific surface properties required for successful long-term operation in the nano world,” said Dr Sinha.
For example, the surface of the lotus leaf has a unique texture that provides super hydrophobic properties that allow for self-cleaning when a drop of dew rolls down the leaf. Our own hip and knee joints are able to work tirelessly because a network of collagen fibre and proteoglycan molecules helps to trap water thus forming a gel-like layer which helps in the lubrication process. Many small organisms such as bacteria have also developed unique molecules that show a lubricious nature. Thus, a study of the natural systems would help in mimicking “nature-designed” surfaces to address engineering issues, such as adhesion and friction, that we currently face in the development of micro machines.
Their research will bring together mechanical engineers, material scientists, physicists and chemists to find an enabling solution to a multi-disciplinary problem. The team hopes their effort will help strengthen Singapore in becoming a world-class centre for research and commercialisation of microsystems and medical devices.
The team’s latest findings on the lubrication of MEMS material (Friction, adhesion and wear durability of an ultra-thin PFPE-coated 3-Glycidoxypropyltrimethoxy silane self-assembled monolayer on a Si surface) was published in Philosophical Magazine in August 2007.
The team led by Dr Sinha include four international collaborators from Basel University (Switzerland), Imperial College London (UK), Indian Institute of Science (India) and Brown University (USA), and seven members from the Department of Mechanical Engineering, NUS – Prof Lim Seh Chun, Assoc Prof Vincent Tan, Assoc Prof Lim Siak Piang, Assoc Prof Lim Kian Meng, Dr Zhou Guangya, Dr Choo Jian Huei and Dr Nalam Satyanarayarana.
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