Tag Archives: piezoelectronics

Cardiac pacemakers: Korea’s in vivo demonstration of a self-powered and UK’s breath-based approach

As i best I can determine ,the last mention of a self-powered pacemaker and the like on this blog was in a Nov. 5, 2012 posting (Developing self-powered batteries for pacemakers). This latest news from The Korea Advanced Institute of Science and Technology (KAIST) is, I believe, the first time that such a device has been successfully tested in vivo. From a June 23, 2014 news item on ScienceDaily,

As the number of pacemakers implanted each year reaches into the millions worldwide, improving the lifespan of pacemaker batteries has been of great concern for developers and manufacturers. Currently, pacemaker batteries last seven years on average, requiring frequent replacements, which may pose patients to a potential risk involved in medical procedures.

A research team from the Korea Advanced Institute of Science and Technology (KAIST), headed by Professor Keon Jae Lee of the Department of Materials Science and Engineering at KAIST and Professor Boyoung Joung, M.D. of the Division of Cardiology at Severance Hospital of Yonsei University, has developed a self-powered artificial cardiac pacemaker that is operated semi-permanently by a flexible piezoelectric nanogenerator.

A June 23, 2014 KAIST news release on EurekAlert, which originated the news item, provides more details,

The artificial cardiac pacemaker is widely acknowledged as medical equipment that is integrated into the human body to regulate the heartbeats through electrical stimulation to contract the cardiac muscles of people who suffer from arrhythmia. However, repeated surgeries to replace pacemaker batteries have exposed elderly patients to health risks such as infections or severe bleeding during operations.

The team’s newly designed flexible piezoelectric nanogenerator directly stimulated a living rat’s heart using electrical energy converted from the small body movements of the rat. This technology could facilitate the use of self-powered flexible energy harvesters, not only prolonging the lifetime of cardiac pacemakers but also realizing real-time heart monitoring.

The research team fabricated high-performance flexible nanogenerators utilizing a bulk single-crystal PMN-PT thin film (iBULe Photonics). The harvested energy reached up to 8.2 V and 0.22 mA by bending and pushing motions, which were high enough values to directly stimulate the rat’s heart.

Professor Keon Jae Lee said:

“For clinical purposes, the current achievement will benefit the development of self-powered cardiac pacemakers as well as prevent heart attacks via the real-time diagnosis of heart arrhythmia. In addition, the flexible piezoelectric nanogenerator could also be utilized as an electrical source for various implantable medical devices.”

This image illustrating a self-powered nanogenerator for a cardiac pacemaker has been provided by KAIST,

This picture shows that a self-powered cardiac pacemaker is enabled by a flexible piezoelectric energy harvester. Credit: KAIST

This picture shows that a self-powered cardiac pacemaker is enabled by a flexible piezoelectric energy harvester.
Credit: KAIST

Here’s a link to and a citation for the paper,

Self-Powered Cardiac Pacemaker Enabled by Flexible Single Crystalline PMN-PT Piezoelectric Energy Harvester by Geon-Tae Hwang, Hyewon Park, Jeong-Ho Lee, SeKwon Oh, Kwi-Il Park, Myunghwan Byun, Hyelim Park, Gun Ahn, Chang Kyu Jeong, Kwangsoo No, HyukSang Kwon, Sang-Goo Lee, Boyoung Joung, and Keon Jae Lee. Advanced Materials DOI: 10.1002/adma.201400562
Article first published online: 17 APR 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

There was a May 15, 2014 KAIST news release on EurekAlert announcing this same piece of research but from a technical perspective,

The energy efficiency of KAIST’s piezoelectric nanogenerator has increased by almost 40 times, one step closer toward the commercialization of flexible energy harvesters that can supply power infinitely to wearable, implantable electronic devices

NANOGENERATORS are innovative self-powered energy harvesters that convert kinetic energy created from vibrational and mechanical sources into electrical power, removing the need of external circuits or batteries for electronic devices. This innovation is vital in realizing sustainable energy generation in isolated, inaccessible, or indoor environments and even in the human body.

Nanogenerators, a flexible and lightweight energy harvester on a plastic substrate, can scavenge energy from the extremely tiny movements of natural resources and human body such as wind, water flow, heartbeats, and diaphragm and respiration activities to generate electrical signals. The generators are not only self-powered, flexible devices but also can provide permanent power sources to implantable biomedical devices, including cardiac pacemakers and deep brain stimulators.

However, poor energy efficiency and a complex fabrication process have posed challenges to the commercialization of nanogenerators. Keon Jae Lee, Associate Professor of Materials Science and Engineering at KAIST, and his colleagues have recently proposed a solution by developing a robust technique to transfer a high-quality piezoelectric thin film from bulk sapphire substrates to plastic substrates using laser lift-off (LLO).

Applying the inorganic-based laser lift-off (LLO) process, the research team produced a large-area PZT thin film nanogenerators on flexible substrates (2 cm x 2 cm).

“We were able to convert a high-output performance of ~250 V from the slight mechanical deformation of a single thin plastic substrate. Such output power is just enough to turn on 100 LED lights,” Keon Jae Lee explained.

The self-powered nanogenerators can also work with finger and foot motions. For example, under the irregular and slight bending motions of a human finger, the measured current signals had a high electric power of ~8.7 μA. In addition, the piezoelectric nanogenerator has world-record power conversion efficiency, almost 40 times higher than previously reported similar research results, solving the drawbacks related to the fabrication complexity and low energy efficiency.

Lee further commented,

“Building on this concept, it is highly expected that tiny mechanical motions, including human body movements of muscle contraction and relaxation, can be readily converted into electrical energy and, furthermore, acted as eternal power sources.”

The research team is currently studying a method to build three-dimensional stacking of flexible piezoelectric thin films to enhance output power, as well as conducting a clinical experiment with a flexible nanogenerator.

In addition to the 2012 posting I mentioned earlier, there was also this July 12, 2010 posting which described research on harvesting biomechanical movement ( heart beat, blood flow, muscle stretching, or even irregular vibration) at the Georgia (US) Institute of Technology where the lead researcher observed,

…  Wang [Professor Zhong Lin Wang at Georgia Tech] tells Nanowerk. “However, the applications of the nanogenerators under in vivo and in vitro environments are distinct. Some crucial problems need to be addressed before using these devices in the human body, such as biocompatibility and toxicity.”

Bravo to the KAIST researchers for getting this research to the in vivo testing stage.

Meanwhile at the University of Bristol and at the University of Bath, researchers have received funding for a new approach to cardiac pacemakers, designed them with the breath in mind. From a June 24, 2014 news item on Azonano,

Pacemaker research from the Universities of Bath and Bristol could revolutionise the lives of over 750,000 people who live with heart failure in the UK.

The British Heart Foundation (BHF) is awarding funding to researchers developing a new type of heart pacemaker that modulates its pulses to match breathing rates.

A June 23, 2014 University of Bristol press release, which originated the news item, provides some context,

During 2012-13 in England, more than 40,000 patients had a pacemaker fitted.

Currently, the pulses from pacemakers are set at a constant rate when fitted which doesn’t replicate the natural beating of the human heart.

The normal healthy variation in heart rate during breathing is lost in cardiovascular disease and is an indicator for sleep apnoea, cardiac arrhythmia, hypertension, heart failure and sudden cardiac death.

The device is then briefly described (from the press release),

The novel device being developed by scientists at the Universities of Bath and Bristol uses synthetic neural technology to restore this natural variation of heart rate with lung inflation, and is targeted towards patients with heart failure.

The device works by saving the heart energy, improving its pumping efficiency and enhancing blood flow to the heart muscle itself.  Pre-clinical trials suggest the device gives a 25 per cent increase in the pumping ability, which is expected to extend the life of patients with heart failure.

One aim of the project is to miniaturise the pacemaker device to the size of a postage stamp and to develop an implant that could be used in humans within five years.

Dr Alain Nogaret, Senior Lecturer in Physics at the University of Bath, explained“This is a multidisciplinary project with strong translational value.  By combining fundamental science and nanotechnology we will be able to deliver a unique treatment for heart failure which is not currently addressed by mainstream cardiac rhythm management devices.”

The research team has already patented the technology and is working with NHS consultants at the Bristol Heart Institute, the University of California at San Diego and the University of Auckland. [emphasis mine]

Professor Julian Paton, from the University of Bristol, added: “We’ve known for almost 80 years that the heart beat is modulated by breathing but we have never fully understood the benefits this brings. The generous new funding from the BHF will allow us to reinstate this natural occurring synchrony between heart rate and breathing and understand how it brings therapy to hearts that are failing.”

Professor Jeremy Pearson, Associate Medical Director at the BHF, said: “This study is a novel and exciting first step towards a new generation of smarter pacemakers. More and more people are living with heart failure so our funding in this area is crucial. The work from this innovative research team could have a real impact on heart failure patients’ lives in the future.”

Given some current events (‘Tesla opens up its patents’, Mike Masnick’s June 12, 2014 posting on Techdirt), I wonder what the situation will be vis à vis patents by the time this device gets to market.

Getting to know your piezoelectrics

It took me a couple of tries before I could see the butterfly in the neutron scattering image (on the left), which illustrates work undertaken in an attempt to better understand piezoelectrics (found in hard drives, loud speakers, etc.) by researchers at Simon Fraser University (Vancouver area, Canada) and the US National Institute of Standards and Technology.

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive "butterfly" shape quite different from that of PZT, in which the atoms are more regularly spaced. Credit: NIST

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive “butterfly” shape quite different from that of PZT, in which the atoms are more regularly spaced.
Credit: NIST

A Jan. 30, 2014 news release on EurekAlert (also found on on the NIST website where it’s dated Jan. 29, 2014) describes piezoelectrics,

Piezoelectrics—materials that can change mechanical stress to electricity and back again—are everywhere in modern life. Computer hard drives. Loud speakers. Medical ultrasound. Sonar. Though piezoelectrics are a widely used technology, there are major gaps in our understanding of how they work. Now researchers at the National Institute of Standards and Technology (NIST) and Canada’s Simon Fraser University believe they’ve learned why one of the main classes of these materials, known as relaxors, behaves in distinctly different ways from the rest and exhibit the largest piezoelectric effect. And the discovery comes in the shape of a butterfly. …

The news release goes on to explain piezoelectrics and provide details about how the researchers made their discovery,

The team examined two of the most commonly used piezoelectric compounds—the ferroelectric PZT and the relaxor PMN—which look very similar on a microscopic scale. Both are crystalline materials composed of cube-shaped unit cells (the basic building blocks of all crystals) that contain one lead atom and three oxygen atoms. The essential difference is found at the centers of the cells: in PZT these are randomly occupied by either one zirconium atom or one titanium atom, both of which have the same electric charge, but in PMN one finds either niobium or manganese, which have very different electric charges. The differently charged atoms produce strong electric fields that vary randomly from one unit cell to another in PMN and other relaxors, a situation absent in PZT.

“PMN-based relaxors and ferroelectric PZT have been known for decades, but it has been difficult to identify conclusively the origin of the behavioral differences between them because it has been impossible to grow sufficiently large single crystals of PZT,” says the NIST Center for Neutron Research (NCNR)’s Peter Gehring. “We’ve wanted a fundamental explanation of why relaxors exhibit the greatest piezoelectric effect for a long time because this would help guide efforts to optimize this technologically valuable property.”

A few years ago, scientists from Simon Fraser University found a way to make crystals of PZT large enough that PZT and PMN crystals could be examined with a single tool for the first time, permitting the first apples-to-apples comparison of relaxors and ferroelectrics. That tool was the NCNR’s neutron beams, which revealed new details about where the atoms in the unit cells were located. In PZT, the atoms sat more or less right where they were expected, but in the PMN, their locations deviated from their expected positions—a finding Gehring says could explain the essentials of relaxor behavior.

“The neutron beams scatter off the PMN crystals in a shape that resembles a butterfly,” Gehring says. “It gives a characteristic blurriness that reveals the nanoscale structure that exists in PMN—and in all other relaxors studied with this method as well—but does not exist in PZT. It’s our belief that this butterfly-shaped scattering might be a characteristic signature of relaxors.”

Additional tests the team performed showed that PMN-based relaxors are over 100 percent more sensitive to mechanical stimulation compared to PZT, another first-time measurement. Gehring says he hopes the findings will help materials scientists do more to optimize the behavior of piezoelectrics generally.

Here’s a citation for the researchers’ paper,

Role of random electric fields in relaxors by Daniel Phelan, Christopher Stock, Jose A. Rodriguez-Rivera, Songxue Chia, Juscelino Leão, Xifa Long, Yujuan Xie, Alexei A. Bokov, Zuo-Guang Ye, Panchapakesan Ganesh, and Peter M. Gehring. Proceedings of the National Academy of Sciences, Jan. 21, 2014. DOI:10.1073/pnas.1314780111

This paper is behind a paywall.

Developing self-powered batteries for pacemakers

Imagine having your chest cracked open every time your pacemaker needs to have its battery changed? It’s not a pleasant thought and researchers are working on a number of approaches to change that situation.  Scientists from the University of Michigan have presented the results from some preliminary testing of a device that harvests energy from heartbeats (from the Nov. 4, 2012 news release on EurekAlert),

In a preliminary study, researchers tested an energy-harvesting device that uses piezoelectricity — electrical charge generated from motion. The approach is a promising technological solution for pacemakers, because they require only small amounts of power to operate, said M. Amin Karami, Ph.D., lead author of the study and research fellow in the Department of Aerospace Engineering at the University of Michigan in Ann Arbor.

Piezoelectricity might also power other implantable cardiac devices like defibrillators, which also have minimal energy needs, he said.

Today’s pacemakers must be replaced every five to seven years when their batteries run out, which is costly and inconvenient, Karami said.

A University of Michigan at Ann Arbor March 2, 2012 news release provides more technical detail about this energy-harvesting battery which the researchers had not then tested,

… A hundredth-of-an-inch thin slice of a special “piezoelectric” ceramic material would essentially catch heartbeat vibrations and briefly expand in response. Piezoelectric materials’ claim to fame is that they can convert mechanical stress (which causes them to expand) into an electric voltage.

Karami and his colleague Daniel Inman, chair of Aerospace Engineering at U-M, have precisely engineered the ceramic layer to a shape that can harvest vibrations across a broad range of frequencies. They also incorporated magnets, whose additional force field can drastically boost the electric signal that results from the vibrations.

The new device could generate 10 microwatts of power, which is about eight times the amount a pacemaker needs to operate, Karami said. It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute. That’s well below and above the normal range.

Karami and Inman originally designed the harvester for light unmanned airplanes, where it could generate power from wing vibrations.

Since March 2012, the researchers have tested the prototype (from the Nov. 4, 2012 news release on EurekAlert),

Researchers measured heartbeat-induced vibrations in the chest. Then, they used a “shaker” to reproduce the vibrations in the laboratory and connected it to a prototype cardiac energy harvester they developed. Measurements of the prototype’s performance, based on sets of 100 simulated heartbeats at various heart rates, showed the energy harvester performed as the scientists had predicted — generating more than 10 times the power than modern pacemakers require. The next step will be implanting the energy harvester, which is about half the size of batteries now used in pacemakers, Karami said. Researchers hope to integrate their technology into commercial pacemakers.

There are other teams working on energy-harvesting batteries, in my July 12, 2010 posting I mentioned a team led by Professor Zhong Lin Wang at Georgia Tech (Georgia Institute of Technology in the US) which is working on batteries that harvest energy from biomechanical motion such as heart beats, finger tapping, breathing, etc.

Dem bones, dem bones, dem dry bones

Making sounds with bones—but not as you might imagine.

Image from slideshow of Transjuicer exhibit in Science Gallery, Dublin, 2011 and John Curtin Gallery, Perth 2010

Christopher Mims in his Dec. 27, 2011 (?) article for Fast Company explains what artist Boo Chapple is doing with her Transjuicer installation of speakers made from bone tissue,

Turned on its head, bone’s response to physical stress can be used to produce music—or at least musical tones. That’s what artist Boo Chapple discovered during the course of a year-long collaboration at the University of Western Australia’s SymbioticA lab, the only research facility in the world devoted to providing access to wet labs to artists and artistically minded researchers.

When Chapple began this project, she knew that extensive scientific literature suggested bone had what are known as piezoelectric properties. Basically, when a piezoelectric material is bent, compressed, or otherwise physically stressed, it generates an electric charge. Conversely, applying an electric charge to a piezoelectric material can change its shape. This has made piezoelectrics the backbone of countless environmental sensors and tiny actuators.

Poring through this literature, Chapple realized that applying a current to bone at just the right frequency should make it vibrate like the diaphragm in an audio speaker. And because bone retains its piezoelectric properties even when it’s no longer living, it should be fairly straightforward to transform any old bone into the world’s most outre audio component.

Because Chapple is an artist and not a technologist, her goal wasn’t to pursue this technique until it yielded a new product. Rather, the point was to accomplish what all good art can: “making strange” otherwise familiar objects.

I first heard about the SymbioticA lab when they showed their Fish & Chips project (the report I’ve linked to is undated) at the 2001 Ars Electronic annual event in Linz, Austria. I never did get to see the performance (fish neurons grown on silicon chips and hooked up to software and musical instruments) but their work remains a source of great interest to me. (I last mentioned SymbioticA in my July 5, 2011 posting where they were scheduled for the same session that I was, at the 2011 ISEA conference in Istanbul.)

Here’s a bit more about the SymbioticA lab at the University of Western Australia (from their home page),

SymbioticA is a research facility dedicated to artistic inquiry into knowledge and technology in the life sciences.

Our research embodies:

  • identifying and developing new materials and subjects for artistic manipulation
  • researching strategies and implications of presenting living-art in different contexts
  • developing technologies and protocols as artistic tool kits.

Having access to scientific laboratories and tools, SymbioticA is in a unique position to offer these resources for artistic research. Therefore, SymbioticA encourages and favours research projects that involve hands on development of technical skills and the use of scientific tools.

The research undertaken at SymbioticA is speculative in nature. SymbioticA strives to support non-utilitarian, curiosity based and philosophically motivated research.

Boo Chapple, a resident at the SymbioticA Lab, had this to say about her installation, Transjuicer, and science when it was at Dublin’s Science Gallery (excerpted from the Visceral Interview),

Do you think that work like yours helps to open up science to public discussion and debate; and does this interest you?

I’m not sure that Transjuicer is so much about science as it is about belief, the economy of human-animal relations, and the politics of material transformation. These are all things that are inherent to the practice of science but perhaps not what one might think of when one thinks of public debate around particular scientific discoveries, or technologies.

While I am interested in the philosophical parameters of these debates, I do not see my art practice as an instrument of communication in this respect, nor is Transjuicer engaged with any hot topics of the moment, or designed in such a way as to reveal the technical processes that were employed in making the bone audio speakers.

The work being done at the SymbioticA lab is provocative in the best sense, i.e., meant to provoke thought and discussion.

Noisy new world with clothing that sings and records and varnishes that ring alarms

They’re called functional fibres and a team at MIT (Massachusetts Institute of Technology) has taken another step forward in achieving fibres that can produce and detect sound. From the news item on physorg.com,

For centuries, “man-made fibers” meant the raw stuff of clothes and ropes; in the information age, it’s come to mean the filaments of glass that carry data in communications networks. But to Yoel Fink, an Associate professor of Materials Science and principal investigator at MIT’s Research Lab of Electronics, the threads used in textiles and even optical fibers are much too passive. For the past decade, his lab has been working to develop fibers with ever more sophisticated properties, to enable fabrics that can interact with their environment.

… Applications could include clothes that are themselves sensitive microphones, for capturing speech or monitoring bodily functions, and tiny filaments that could measure blood flow in capillaries or pressure in the brain. The paper, whose authors also include Shunji Egusa, a former postdoc in Fink’s lab, and current lab members Noémie Chocat and Zheng Wang, appeared on Nature Materials‘ website on July 11, and the work it describes was supported by MIT’s Institute for Soldier Nanotechnologies, the National Science Foundation and the U.S. Defense Department’s Defense Advanced Research Projects Agency. [emphases mine]

Interesting to note all of the military interest.

The heart of the new acoustic fibers is a plastic commonly used in microphones. By playing with the plastic’s fluorine content, the researchers were able to ensure that its molecules remain lopsided — with fluorine atoms lined up on one side and hydrogen atoms on the other — even during heating and drawing. The asymmetry of the molecules is what makes the plastic “piezoelectric,” meaning that it changes shape when an electric field is applied to it.

I’m not sure how this fits with Professor Zhong Lin Wang’s work in the field of piezotronics  (July 12, 2010 posting) and I’m not looking at the technical aspect so much as the social impact of clothing made of fibres that can harvest biomechanical energy and/or record sound and/or produce sound. In other words, what’s the social impact? In all the talk about developing new products and getting them to market,  I haven’t found that much discussion about whether people are going to adopt products that are constantly monitoring their health or given to making a sound for one reason or another. When you add in the other work on such things as varnishes that emit sounds as they cool or heat (Feb. 3, 2010, 2nd excerpt, last paragraph), you have to come to the conclusion that at the very least it’s going to be a very noisy world in the future. Questions that come to mind include: will these fibres that can monitor our health or record sounds or the varnishes that sound alarms have an off button? What happens if they malfunction?