World's tiniest nano-engine is powered by LIGHT: 'Ant' device is so small it could one day enter living cells to fight disease

  • Device consists of charged particles of gold bound into a polymer resin gel
  • This absorbs and stores energy from lasers, causing it to shrink 
  • Power is then released instantly thanks to the device's spring-like reaction
  • Nano-engine is a hundred times more powerful than any muscle

The potential for nano-machines that 'work' inside the human body took a step closer to reality today after researchers designed a microscopic nano-engine. 

Just a few billionths of a metre in size, the world's tiniest engine uses light to power itself and works at scales much smaller than a human cell.  

The nanoscale engine could form the basis of future nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease. 

Just a few billionths of a metre in size, the world's tiniest engine (illustrated) uses light to power itself and works at scales smaller than a human cell. The nanoscale engine could form the basis of  nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease

Just a few billionths of a metre in size, the world's tiniest engine (illustrated) uses light to power itself and works at scales smaller than a human cell. The nanoscale engine could form the basis of nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease

The simple device consists of tiny charged particles of gold bound into a polymer resin gel.

These 'actuating nano-transducers', or Ants, can deliver almost a hundred times more force per unit weight than any existing engine or muscle cell, said the Cambridge scientists who developed them.

When the Ant engine is heated with a laser, the polymer gel expels water and collapses.

This forces the gold nanoparticles to bind together in tight clusters.

WORLD'S TINIEST THERMOMETER 

Biochemists recently designed DNA strands that fold and unfold at specific temperatures to produce a nanoscale themometer.

By combining several of these together they were able to measure temperatures between 86°F (30°C) and 185°F (85°C). 

When heated DNA undergoes a process known as denaturation, where it loses structure and unfolds.

Strands of DNA are held together by hydrogen bonds of different strength according to the molecules involved in the bond.

Not as strong as atomic bonds, these hydrogen bonds can be broken with relatively low levels of energy, such as moderate increases in heat. 

The researchers said this tiny thermometer could provide new ways of monitoring temperatures at a cellular level. 

When the laser is turned off, the device instantly cools and water is re-absorbed.

This pushes the gold nanoparticles apart, releasing the stored energy as useable work.

'It's like an explosion,' said Dr Tao Ding from the Cavendish Laboratory, first author of the paper published today in the journal Proceedings of the US National Academy of Sciences.

'We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them.'

Co-author Dr Ventsislav Valev added: 'We know that light can heat up water to power steam engines, now we can use light to power a piston engine at the nanoscale.'

The researchers think this development could make the science fiction dream of nano-machines and robots a reality. 

The Ant engine is bio-compatible, cheap to make, and energy efficient, they claimed.

'The smart part is we make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible,' said research leader Professor Jeremy Baumberg, who coined the term Ant engine. 

When the 'actuating nano-transducers', or Ants, engine is heated with a laser, the polymer gel expels water and collapses. This forces gold nanoparticles to bind together (pictured). When the laser is turned off, the device cools and water is re-absorbed. This pushes the gold nanoparticles apart, releasing the stored energy 

When the 'actuating nano-transducers', or Ants, engine is heated with a laser, the polymer gel expels water and collapses. This forces gold nanoparticles to bind together (pictured). When the laser is turned off, the device cools and water is re-absorbed. This pushes the gold nanoparticles apart, releasing the stored energy 

The Ant engine is bio-compatible, cheap to make, and energy efficient. The researchers make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible. The rising temperatures and release of energy is illustrated

The Ant engine is bio-compatible, cheap to make, and energy efficient. The researchers make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible. The rising temperatures and release of energy is 

Van der Waals energy attracts atoms and molecules together and is a weak electric force that works at short distances when atoms spontaneously generate a positive-negative dipole pair due to their proximity.

Van der Waals forces are what holds water molecules together in a liquid and are also responsible for the ability of geckos to cling to smooth surfaces.

The forces are named after their discoverer, the 19th century Dutch scientist Johannes Diderik van der Waals. 

The new engine could form the basis of nano-machines that can navigate in any watery situation, such as inside a living body, and sense the environment around them.

 They could even enter living cells to fight disease. 

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