Matt Smith

Engineers race to create real sonic screwdriver

There could be some real-life applications for this fictional device from the Doctor Who universe.

It is a gadget that takes its place on the roster of tantalisingly feasible sci-fi hardware, next to the ray-gun and the lightsaber. Doctor Who's sonic screwdriver is modest enough to be possible, surely? One man who ought to know is Bruce Drinkwater, professor of sonics at Bristol University, who has been working on practical applications for sonic energy in several different sectors.

A few years ago, the university announced findings pointing out the similarities of the experiments being conducted there and at the University of Dundee, and how they could possibly be used to create a real-life sonic screwdriver - the type that the Doctor regularly uses to get out of a tight situation.

The analogy with Doctor Who is quite important in explaining that sonics, specifically ultrasonics, can produce usable energy. In reality, however, we are many years away from the type of applications that the fictional sonic screwdriver has been used for. Indeed, the Doctor's device resembles not so much a screwdriver as a high-tech Swiss Army knife - something that makes for, dare we say it, a very convenient plot device.

Beyond the screwdriver

When the original sonic screwdriver was introduced, during the second regeneration of the Doctor, played by Patrick Troughton, it was just that: a screwdriver that used energy to propel screws and unlock doors.

This was at a time when 'sonic' was associated with the modern era of jet engines breaking the sound barrier and ultrasonic sensors used in medical applications, such as detecting a foetus in the womb. Beyond this, very few practical applications have been discovered for sonic energy.

But Professor Drinkwater hopes that this could change in a few years' time with sonics being used to manipulate minuscule objects. As we move further into nanoscale technologies - electronic, mechanical and biological, and often a combination of all three - this could potentially offer a solution to manipulating structures, many of which are quite fragile at this scale.

In 2004, Dr Mark Thurber from New York University developed a mathematical model for matching sound frequency, oscillator design, and work applications that make it practical to use low-frequency oscillators to convert sound into energy. Basically, low-frequency sound is used to produce a pressure differential on two opposite sides of an object and this difference causes the object to move.

Sonic energy in society

One application that Professor Drinkwater considers will be a prime candidate for sonic energy is medical research. The manipulation of individual cells will become increasingly important in the growing field of synthetic biology and in vitro cell research. Therefore, it is likely that sonic screwdriver-type devices will be used by a doctor in the future - although not the Timelord variety.

Professor Drinkwater's device - based on small, electronic, easily integrated ultrasonic transducers - is known as the sonotweezer. He envisages widespread use ranging from tissue engineering through to micro- and potentially nano-materials, particle/cell sorting and counting, bioassay technology, and sensing and detection. Forensic science and border security, for example, could benefit from the device in terms of detecting banned particulants common in narcotics and chemicals used to assemble bombs.

The use of bioparticles is developing rapidly and has already been shown to work safely. However, existing systems are limited by their reliance on resonance between piezoelectric plates, in turn fixing the nodal points towards which particles move or their need to trap particles before physically moving the transducers. In essence, Professor Drinkwater is turning sonic waves from backward-and-forward motion to constant forward motion.

"We will use electronically ultrasonic transducer systems to produce and dynamically modify the potential/force landscape which allows us to control particles in sonotweezer devices," he explains.

Sonic experiments

PhD students at the Bristol laboratory have been carrying out intricate laboratory experiments - carefully fine-tuning the frequencies and upgrading the devices to produce better results, and the experiments are in their fourth year of operation.

A series of silicone particles are immersed in fluid on a petri dish. Surrounding the petri dish are transducers that transmit energy controlled via an electronic module. When a sonic charge is applied, the particles instantly line up like microscopic synchronised swimmers preparing to form a water ballet.

Another experiment involves a simple set of '100 speakers connected to a sonic sound source. Polystyrene balls are placed within a sonic field, making it possible to create a grid of balls suspended in mid-air which are only held there by the sonic waves travelling through the speakers.

The first experiment demonstrates the more practical applications where sonic energy can be deployed in medical and research fields. The second experiment has been designed to educate the general public about the value of sonic energy. It has been taken to the annual Big Bang Fair - a science, technology, engineering and manufacturing jamboree aimed at schoolchildren.

Various groups have demonstrated the basic principles of ultrasonic energy and the race is on to develop devices to best exploit this phenomenon. Bristol University established the feasibility of the concept of electronic sonic devices to manipulate objects, but now at a more practical scale.

Additionally, researchers at the University of Southampton have demonstrated that ultrasound can manipulate bioparticles and is both safe and suitable for miniaturisation.

The Bristol group demonstrated how the new device can improve on existing particle and cellular manipulation devices. Such devices could be used in forensic science for cell sorting and counting of micro- and potentially nano-materials, sensing and detection. In tissue engineering, for instance, researchers can potentially bring together small populations of cells for multi-layered structures that better replicate such things as the lining of the lung.

It's a small world

While it is already possible to manipulate cells individually, the sonotweezers can operate on groups of cells and produce artificial tissue on a much larger scale.

"In all these applications, crucial processing steps require the movement of individual particles or small clusters of particles from one location to another," says Professor Drinkwater.

Electronic sonotweezers will allow very fine control of manipulation, involving no moving parts, scaling down to microlevel, but maintaining the higher forces available from ultrasound.

But in a world where miniaturisation is increasing in mechanical and electronic manufacture, is it possible that the properties of sonic energy could be useful as a tool used for engineers and technicians?

In fact, researchers at Dundee University, working very closely with Professor Drinkwater's team, claim to have invented a'real-life Doctor Who-style sonic screwdriver.

The prototype has successfully used ultrasound waves to lift and rotate a rubber disc floating in a cylinder of water - the first time ultrasound has turned objects rather than simply pushed them. The team, which includes both engineers and physicists, believe the applications can only expand.

3D printers

Such a device could be incorporated into a 3D printer to manipulate small and delicate components. 3D printers use additive processes to construct solid objects and some mechanical moving parts. But incorporating complex electronics is far more difficult.

The development of 3D printers has gathered pace greatly over the past ten years - to the extent that the first commercially available 3D printer will soon be available in high-street electronics retailer Maplin. Such small-scale manufacturing offers the possibility of creating complex objects far more cheaply. However, they currently require the investment and construction of multi-billion-dollar wafer fabrication facilities.

"Like Doctor Who's own device, our sonic screwdriver is capable of much more than just spinning things around," claims Dr Mike MacDonald of the Institute for Medical Science and Technology at Dundee.

But it appears that the first major application of sonic energy will likely be in the medical sector. While the use of ultrasound is not uncommon - think about the surgeons and medical practitioners who already use it to avoid the need for exploratory surgery - sonic energy could be used to steer objects such as drug capsules to precise locations, making it an invaluable surgeon's tool. We may not need a Tardis to see sonics being used in our lifetime.

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