Noise power on adhesion: New model may help robotic fingers, made of a soft surface, manipulate small objects

Dec. 17, 2012 — Imagine a solid ball rolling down a slightly inclined ramp. What could be perceived as child's play is the focus of serious theoretical research by Manoj Chaudhury and Partho Goohpattader, two physicists from Lehigh University, Bethlehem, Pennsylvania, USA.

Their study, which is about to be published in EPJ E, has one thing in common with childhood behaviour. It introduces a mischievous idea, namely studying the effect of random noise, such as vibrations, on the ball. They found it could lower the energy barrier to set the ball in motion.

The authors used a ramp with a micro-textured surface. This surface is akin to that of a gecko's feet, made of so-called microfibrils capable of adhering to any surface by deforming elastically. They then studied the effect of vibration on a ball left on the top of such a textured ramp. They found that the sphere starts rolling when subjected to a computer-generated random vibration. To set the ball in motion requires activation energy, the model shows. It has been long known that the same applies to the adhesion of molecules, on a much smaller scale, as predicted theoretically by the so-called Arrhenius kinetics. This study pinpoints a finite threshold of intensity for the vibration noise above which the ball is set in motion.

This finding could have implications for the removal of water droplets from super-hydrophobic surfaces such as plant leaves. Other applications could also include gecko feet-mimetic adhesives, better adhesion of rubber tires on roads, and the use of fluids, instead of electronics, to perform a digital operation. In addition, new MicroElectroMechanical systems (MEMs), based on robotic fingers capable of displacing a small object, could be assisted by noise.

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The above story is reprinted from materials provided by Springer Science+Business Media, via AlphaGalileo.

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Journal Reference:

M. K. Chaudhury, P. S. Goohpattader. Noise-activated dissociation of soft elastic contacts. The European Physical Journal E, 2012; 35 (12) DOI: 10.1140/epje/i2012-12131-9

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Synthetic biology research: Could fuel for cars or household power supplies be created from naturally-occurring fatty acids?

Dec. 17, 2012 — Writing in PNAS, the researchers have shown that the emerging field of synthetic biology can be used to manipulate hydrocarbon chemicals, found in soaps and shampoos, in cells.

This development, discovered with colleagues at the University of Turku in Finland, could mean fuel for cars or household power supplies could be created from naturally-occurring fatty acids.

The researchers, led by Professor Nick Turner from The University of Manchester, used synthetic biology to hijack the naturally-existing fatty acids and direct those fatty molecules towards the production of ready-to-use fuel and household chemicals.

Hydrocarbon chemicals are everywhere in our daily lives; as fragrance in soap, thickener in shampoo and fuel in the car. Their number of carbons and whether they are acid, aldehyde, alcohol or alkane are important parameters that influence how toxic they are to biological organisms, the potential for fuel and their olfactory perception as aroma compounds.

The breakthrough allows researchers to further explore how to create renewable energy from sustainable sources, and the advance could lead to more innovative ways of sourcing fuel from natural resources.

Synthetic biology is an area of biological research and technology that combines science and engineering for the benefit of society. Significant advances have been made in this field in recent years.

Professor Turner said: "In our laboratories in Manchester we currently work with many different biocatalysts that catalyse a range of chemical reactions -- the key is to match up the correct biocatalyst with the specific product you are trying to make.

"Biocatalysts recognise molecules in the way that a lock recognises a key -- they have to fit perfectly together to work. Sometime we redesign the lock so that if can accept a slightly different key allowing us to make even more interesting products.

"In this example we need to make sure that the fatty acid starting materials would be a perfect match for the biocatalysts that we discovered and developed in our laboratories.

"As with many leading areas of science today, in order to make major breakthroughs it is necessary for two or more laboratories around the world to come together to solve challenging problems."

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The above story is reprinted from materials provided by University of Manchester, via EurekAlert!, a service of AAAS.

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Journal Reference:

M. Kalim Akhtar, Nicholas J. Turner, and Patrik R. Jones. Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities. PNAS, December 17, 2012 DOI: 10.1073/pnas.1216516110

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Electricity from water mains: Inline hydropower system generates power from water pipelines

Dec. 10, 2012 — Generating electricity from water is not a new thing. Hydro power stations have already sprung up across the world in China, United States and Canada. However, scientists will not stop exploring advanced technologies for further improvement to benefit people's lives.

Recently, PolyU's Department of Building Services Engineering and the Water Supplies Department (WSD) of the Hong Kong Special Administrative Region Government have been working together to turn water mains into an alternative source of power.

Hong Kong has a network of water mains travelling over 7,800 km, which is comprehensively monitored by WSD using monitoring devices to make sure our water supply remain clean and well-maintained. Water mains need power for those devices. Conventionally, they are putting small turbines into our pipes to produce electricity from drinking water.

Our water main pipes present a real challenge. They are just one metre across and hold far less water volume and potential energy compared to giant water dams, say for example. In pushing the boundaries, specialists in hydrodynamics, mechanical engineering and renewable energy have created a highly efficient device in harnessing the power of water. The resulting turbine is small enough to fit into a pipe, and uses just a fraction of hydro-energy to generate about 80 volts, enough to power four compact fluorescent light bulbs.

The novel device consists of an external hydroelectric generator and highly efficient spherical water turbine which dips into flowing water and reclaims residual pressure. When water passes through, the turbine drives a central rotating shaft and a micro generator to produce electricity.

The key lies in a number of intelligent designs to extract more energy from flowing water. The 8-blade turbine would only take away a fraction of kinetic energy because it strikes an accurate balance between water volume, water pressure and consumption of hydrokinetic energy, which boosts efficiency without reducing the momentum of running water to guarantee a reliable water supply. Turbine blades are carefully sized to intersect the largest possible area of water flow and minimise water bypassing.

To achieve maximum power output, a revolutionary design made the central rotating shaft hollow on the inside to minimise energy losses when driving the generator and utilize the harvested energy in full. The team also made the water more energetic and produced a strong current with a special metal block placed at the centre of the pipe to compress and accelerate the water flow. To further protect our drinking water, the turbine does not have moving parts and does not need any lubricant to eliminate the slightest change of contamination.

The mini-hydro power has been put to test in a number of locations including underground pits and outdoor environments. The principal investigator, Prof. Hong-xing Yang from Department of Building Services Engineering commented, "We have made the water pipes self-sufficient." In full operation, an array of in-pipe turbines is expected to save 700kWh of electricity and reduce 560 kg of carbon dioxide emission per year.

It is not only a green innovation to further cut our reliance on coal-based power plants, but also an engineering triumph that gives WSD an easy access to electricity in areas without power grid, such as treacherous terrains and underground. "This technology also points to viable turbine solutions for waters that have little potential for energy generation," added Prof. Yang.

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The above story is reprinted from materials provided by The Hong Kong Polytechnic University.

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