Tag Archives: MEMS

Wolrd’s smallest FM radio transmitter made out of graphene

I’m always amazed at how often nanotechnology is paired with radio. The latest ‘nanoradio’ innovation is from the University of Columbia School of Engineering. According to a November 18, 2013 news item on ScienceDaily,

 A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, has taken advantage of graphene’s special properties — its mechanical strength and electrical conduction — and created a nano-mechanical system that can create FM signals, in effect the world’s smallest FM radio transmitter.

One of my first ‘nanorado’ stories (in 2007 and predating the existence of this blog) focused on carbon nanotubes and a Zettl Group (Alex Zettl) project at the University of California at Berkeley (from the Zettl Group’s Nanotube Radio: Supplementary materials webpage),

We have constructed a fully functional, fully integrated radio receiver, orders-of-magnitude smaller than any previous radio, from a single carbon nanotube. The single nanotube serves, at once, as all major components of a radio: antenna, tuner, amplifier, and demodulator. Moreover, the antenna and tuner are implemented in a radically different manner than traditional radios, receiving signals via high frequency mechanical vibrations of the nanotube rather than through traditional electrical means. We have already used the nanotube radio to receive and play music from FM radio transmissions such as Layla by Eric Clapton (Derek and the Dominos) and the Beach Boy’s Good Vibrations. The nanotube radio’s extremely small size could enable radical new applications such as radio controlled devices small enough to exist in the human bloodstream, or simply smaller, cheaper, and more efficient wireless devices such as cellular phones.

The group features four songs transmitted via their carbon nanotube radio (from the ‘supplementary materials’ webpage),

A high resolution transmission electron microscope allows us to observe the nanotube radio in action. We have recorded four videos from the electron microscope of the nanotube radio playing four different songs. At the beginning of each video, the nanotube radio is tuned to a different frequency than that of the transmitted radio signal. Thus, the nanotube does not vibrate, and only static noise can be heard. As the radio is brought into tune with the transmitted signal, the nanotube begins to vibrate, which blurs its image in the video, and at the same time, the music becomes audible. The four songs are Good Vibrations by the Beach Boys, Largo from the opera Xerxes by Handel (this was the first song ever transmitted using radio), Layla by Eric Clapton (Derek & the Dominos), and the Main Title from Star Wars by John Williams.

Good Vibrations (Quicktime, 8.06 MB)
Layla (Quicktime, 6.13 MB)
Largo (Quicktime, 8.73 MB)
Star Wars (Quicktime, 8.68 MB)

‘Layla’ is quite scrtachy and barely audible but it is there, if you care to listen to this 2007 carbon nanotube radio project. Now in 2013 we have a graphene radio receiver and this graphene radio project is intended to achieve some of the goals as the carbon nanotube radio project,. From the Nov. 17, 2013 University of Columbia news release on newswise and also on EurekAlert),

“This work is significant in that it demonstrates an application of graphene that cannot be achieved using conventional materials,” Hone says. “And it’s an important first step in advancing wireless signal processing and designing ultrathin, efficient cell phones. Our devices are much smaller than any other sources of radio signals, and can be put on the same chip that’s used for data processing.”

Graphene, a single atomic layer of carbon, is the strongest material known to man, and also has electrical properties superior to the silicon used to make the chips found in modern electronics. The combination of these properties makes graphene an ideal material for nanoelectromechanical systems (NEMS), which are scaled-down versions of the microelectromechanical systems (MEMS) used widely for sensing of vibration and acceleration. For example, Hone explains, MEMS sensors figure out how your smartphone or tablet is tilted to rotate the screen.

In this new study, the team took advantage of graphene’s mechanical ‘stretchability’ to tune the output frequency of their custom oscillator, creating a nanomechanical version of an electronic component known as a voltage controlled oscillator (VCO). With a VCO, explains Hone, it is easy to generate a frequency-modulated (FM) signal, exactly what is used for FM radio broadcasting. The team built a graphene NEMS whose frequency was about 100 megahertz, which lies right in the middle of the FM radio band (87.7 to 108 MHz). They used low-frequency musical signals (both pure tones and songs from an iPhone) to modulate the 100 MHz carrier signal from the graphene, and then retrieved the musical signals again using an ordinary FM radio receiver.

“This device is by far the smallest system that can create such FM signals,” says Hone.

While graphene NEMS will not be used to replace conventional radio transmitters, they have many applications in wireless signal processing. Explains Shepard, “Due to the continuous shrinking of electrical circuits known as ‘Moore’s Law’, today’s cell phones have more computing power than systems that used to occupy entire rooms. However, some types of devices, particularly those involved in creating and processing radio-frequency signals, are much harder to miniaturize. These ‘off-chip’ components take up a lot of space and electrical power. In addition, most of these components cannot be easily tuned in frequency, requiring multiple copies to cover the range of frequencies used for wireless communication.”

Unfortunately I haven’t seen any audio files for this ‘graphene radio’ but here’s a link to and a citation for the 2013 paper ,

Graphene mechanical oscillators with tunable frequency by Changyao Chen, Sunwoo Lee, Vikram V. Deshpande, Gwan-Hyoung Lee, Michael Lekas, Kenneth Shepard, & James Hone. Nature Nanotechnology (2013) doi:10.1038/nnano.2013.232 Published online 17 November 2013

The paper is behind a paywall.

NUSIKIMO: plasma and nanotechnology applications

NUKISIMO's plama and nanotechnology applications? Credit: Shutterstock [downloaded from http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&RCN=36206]

NUKISIMO’s plama and nanotechnology applications? Credit: Shutterstock [downloaded from http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&RCN=36206]

It looks like a jewel, doesn’t it? Unfortunately, there’s no explanation for why this image is offered as an illustration for an Oct. 31, 2013 OORDIS news release (h/t phys.org) about plasma and nanotechnology applications, being worked on as part of the NUSIKIMO (‘Numerical simulations and analysis of kinetic models – applications to plasma physics and nanotechnology’) project,

Plasma is one of the four fundamental states of matter, alongside solid, liquid and gas. Ubiquitous in form, plasma is an ionised gas so energised that electrons have the capacity to break free from their nucleus.

Scientists are keen to shed light on the motion of particles in plasma physics, as well as the dynamics of rarefied gas – a gas whose pressure is much lower than atmospheric pressure. How can this be done? An EU-funded team of researchers has come up with a solution.

Prof. Francis Filbet from Université Claude Bernard Lyon 1 in France decided to tackle the question with mathematical and numerical analyses. He received an European Research Council (ERC) Starting Grant worth almost EUR 500 000 for the NUSIKIMO (‘Numerical simulations and analysis of kinetic models – applications to plasma physics and nanotechnology’) project. Prof Filbet and his research team modelled non-stationary collisional plasma with supercomputers, putting regimes and instabilities under the microscope.

One of the challenges researchers undertook was to approximate kinetic models and to develop novel techniques that could make numerical analysis in kinetic theory possible.

To do this, the team is working on adapting averaging lemmas (proven statements used for obtaining proof of other statements) to examine kinetic equations, including the Boltzmann equation. Devised in 1872, the seven-dimensional equation is used to model the behaviour of gases, but solving it has proved problematic as numerical capabilities fail to capture the complexities involved.

The NUSIKIMO team is also examining asymptotic preserving schemes, which can be described as performant procedures able to solve ‘singularly perturbed problems’ – those for which the character of the problem changes intermittently.

Such problems contain small parameters that cannot be approximated by setting the parameter value to zero. For comparison, an approximation for regular perturbation problems can be obtained when small parameters are set to zero.

Asymptotic preserving schemes were established to help scientists deal with singularly perturbed problems. This is especially the case when they are dealing with kinetic models in a diffusive environment.

Prof. Filbet and his team are developing a method to control numerical entropy (classical thermodynamics) production. Being able to control entropy production, which determines the performance of thermal machines, is an important feature for stability analysis – an assessment that helps us understand what happens to a system when it is perturbed. The researchers believe nonlinear equations could therefore be treated with a strategy based on asymptotic preserving schemes.

Applying these equations to plasma physics is one of the NUSIKIMO goals. The team is evaluating energy transport and seeking to determine the efficiency of plasma heating. The researchers are also looking into the measures required to secure fusion conditions through the interaction of intense, short laser pulses, and schemes like inertial confinement fusion or fast ignition.

Another objective is to apply the equations to microelectromechanical systems (MEMS). Prof. Filbet and his team are developing theoretical and numerical methods to investigate gaseous and liquid flows in micro devices. The key element here is the development of numerical methods. The researchers say: using numerical methods, rather than analytical methods, make modelling the three-dimensional flow geometries in MEMS configurations possible.

The project end date is December 2013 but in the meantime, you can get more information about NUSIKIMO here.

Music can recharge sensors in your body

According to a Jan.26, 2012 news item written by Emil Venere at Purdue University and posted on Nanowerk, researchers have found a new way to recharge batteries in new medical sensors that could be implanted in individuals stricken with aneurysms or bladder incontinence due to paralysis. From the news item,

“You would only need to do this for a couple of minutes every hour or so to monitor either blood pressure or pressure of urine in the bladder,” Ziaie [Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering] said. “It doesn’t take long to do the measurement.”

Findings are detailed in a paper (“A Novel Electromechanical Interrogation Scheme for Implantable Passive Transponders”) to be presented during the IEEE [Institute of Electrical and Electronics Engineers] MEMS [Micro Electro Mechanical Systems] 2012 conference, which will be Jan. 29 to Feb. 2 in Paris. The paper was written by doctoral student Albert Kim, research scientist Teimour Maleki and Ziaie.

“This paper demonstrates the feasibility of the concept,” he said.

As you may have guessed from that last line, this hasn’t been tried on people. According to the news item, the concept was tested using a water-filled balloon.

I checked out Venere’s Jan. 26, 2012 news release on the Purdue University website and am excerpting a few details about how these medical sensors work,

The sensor is capable of monitoring pressure in the urinary bladder and in the sack of a blood vessel damaged by an aneurism. Such a technology could be used in a system for treating incontinence in people with paralysis by checking bladder pressure and stimulating the spinal cord to close the sphincter that controls urine flow from the bladder. More immediately, it could be used to diagnose incontinence. The conventional diagnostic method now is to insert a probe with a catheter, which must be in place for several hours while the patient remains at the hospital.

The writer goes on to describe some of the reasons for why this new technology is being pursued,

“A wireless implantable device could be inserted and left in place, allowing the patient to go home while the pressure is monitored,” Ziaie said.

The new technology offers potential benefits over conventional implantable devices, which either use batteries or receive power through a property called inductance, which uses coils on the device and an external transmitter. Both approaches have downsides. Batteries have to be replaced periodically, and data are difficult to retrieve from devices that use inductance; coils on the implanted device and an external receiver must be lined up precisely, and they can only be about a centimeter apart.

The following image is  the researchers’ new sensor, balanced on a coin,

Researchers have created a new type of miniature pressure sensor, shown here, designed to be implanted in the body. Acoustic waves from music or plain tones drive a vibrating device called a cantilever, generating a charge to power the sensor. (Birck Nanotechnology Center, Purdue University)

I found the description of how the cantilever works and can be recharged quite interesting,

The heart of the sensor is a vibrating cantilever, a thin beam attached at one end like a miniature diving board. Music within a certain range of frequencies, from 200-500 hertz, causes the cantilever to vibrate, generating electricity and storing a charge in a capacitor …

The cantilever beam is made from a ceramic material called lead zirconate titanate, or PZT, which is piezoelectric, meaning it generates electricity when compressed. The sensor is about 2 centimeters long …

A receiver that picks up the data from the sensor could be placed several inches from the patient. Playing tones within a certain frequency range also can be used instead of music.

“But a plain tone is a very annoying sound,” Ziaie said. “We thought it would be novel and also more aesthetically pleasing to use music.”

Researchers experimented with four types of music: rap, blues, jazz and rock.

“Rap is the best because it contains a lot of low frequency sound, notably the bass,” Ziaie said.

“The music reaches the correct frequency only at certain times, for example, when there is a strong bass component,” he said. “The acoustic energy from the music can pass through body tissue, causing the cantilever to vibrate.”

When the frequency falls outside of the proper range, the cantilever stops vibrating, automatically sending the electrical charge to the sensor, which takes a pressure reading and transmits data as radio signals. Because the frequency is continually changing according to the rhythm of a musical composition, the sensor can be induced to repeatedly alternate intervals of storing charge and transmitting data.

“You would only need to do this for a couple of minutes every hour or so to monitor either blood pressure or pressure of urine in the bladder,” Ziaie said. “It doesn’t take long to do the measurement.”

It’s usually a long time from testing a concept (in this case, on a water balloon) to bringing a product to the marketplace. In the meantime, I wonder if this concept will work in the ‘wild’ where people are exposed to rap music accidentally or they like to listen to it themselves, all day long, or they loathe rap music and don’t want to listen for a few minutes every hour.

Finally, I have some special appreciation for Venere as he very neatly explained terms I’ve seen many times but for which I’ve only been able to find complicated definitions. Thank you, Mr. Venere and for a very clear description of this technology.

Back to my roots, writing nanotechnology

This July 18, 2011 news item title, Writing Nanostructures: Heated AFM Tip Allows Direct Fabrication of Ferroelectric Nanostructures On Plastic, on the Science Daily website brought back memories. The first part of the title, Writing Nanostructures, that is. My first project about nanotechnology and the language used to describe it for my master’s degree was titled, Writing Nanotechnology.

This, of course, is something entirely different. From the news item on Science Daily,

Using a technique known as thermochemical nanolithography (TCNL), researchers have developed a new way to fabricate nanometer-scale ferroelectric structures directly on flexible plastic substrates that would be unable to withstand the processing temperatures normally required to create such nanostructures.

The technique, which uses a heated atomic force microscope (AFM) tip to produce patterns, could facilitate high-density, low-cost production of complex ferroelectric structures for energy harvesting arrays, sensors and actuators in nano-electromechanical systems (NEMS) and micro-electromechanical systems (MEMS). The research was reported July 15 in the journal Advanced Materials.

“We can directly create piezoelectric materials of the shape we want, where we want them, on flexible substrates for use in energy harvesting and other applications,” said Nazanin Bassiri-Gharb, co-author of the paper and an assistant professor in the School of Mechanical Engineering at the Georgia Institute of Technology.

I particularly like this picture where the professor is holding something that looks like a pencil as a pointer,

Georgia Tech postdoctoral fellow Suenne Kim holds a sample of flexible polyimide substrate used in research on a new technique for producing ferroelectric nanostructures. Assistant professor Nazanin Bassiri-Gharb points to a feature on the material, while graduate research assistant Yaser Bastani observes. (Credit: Gary Meek)

You can check out the rest  in the Science Daily news item or you can check out the original Georgia Institute of Technology news release (which has more images) written by John Toon.