Tag Archives: harvesting biomechanical motion

A unique design for harvesting biomechanical motion

Researchers have discovered a new technique for doing this according to an April 25, 2022 news item on ScienceDaily,

Harvesting energy from the day-to-day movements of the human body and turning it into useful electrical energy, is the focus of a new piece of research involving a Northumbria University Professor.

Academics from Northwestern Polytechnical University in China, supported by Professor Richard Fu from Northumbria, have developed a unique design for sensors capable of using human movements — such as bending, twisting and stretching — to power wearable technology devices including smart watches and fitness trackers.

An April 25, 2022 Northumbria University press release (also on EurekAlert), which originated the news item, delves further into the topic (Note: Links have been removed),

Self-powered pressure sensors are one of the key components used in these smart electronic devices which are growing in popularity today. The sensors can operate without the need for external power supplies.

Detecting health conditions and measuring performance in sport are among the potential uses for these types of sensors. As a result, they are the focus of extensive research and development, but remain challenging to produce with the performance sensing, flexibility, and sufficient level of power needed for wearable technology.

A new research paper published in the prestigious international scientific journal, Advanced Science, describes how the team led by Professor Weizheng Yuan, Professor Honglong Chang and Associate Professor Kai Tao from Northwestern Polytechnical University (NPU), has worked with Professor Fu to develop a solution.

Their novel method involves using sophisticated materials with pre-patterned pyramid shapes to create friction against the silicone polymer known as polydimethylsiloxane or PDMS. This friction generates a self-powering effect, or triboelectricity, which can significantly enhance the energy available to power a wearable device. 

Professor Tao from NPU explained: “This results in a self-powered tactile sensor with wide environmental tolerance and excellent sensing performance, and it can detect subtle pressure changes by measuring the variations of triboelectric output signal without an external power supply. The sensor design has been tested an is capable of controlling electrical appliances and robotic hands by simulating human finger gestures, confirming its potential for use in wearable technology.”

Professor Fu added: “This self-powered sensor based on hydrogels has a simple fabrication process, but with a superb flexibility, good transparency, fast response and high stability.”

Professor Honglong Chang, Dean of School of Mechanical Engineering at NPU, said Northumbria University is one of their most important international partners.

“One of our important tasks this year is to further promote the cooperative relationship with Northumbria University,” he explained. “We are organising NU-NPU bilateral academic forums this year, and we look forward to establishing strong collaborations in various research areas with Northumbria University.”

Professor Jon Reast, Pro Vice-Chancellor (International) at Northumbria University, said he was delighted with the success of the partnership with NPU. “It’s fantastic that this research collaboration is proving successful and producing such ground-breaking work.

“We work closely with more than 500 partner universities, colleges and schools across the world. Within these, NPU is one of a set of extremely high-quality research-led university partners. The relationship with NPU includes researchers within smart materials engineering as well as smart design and is producing some truly excellent, impactful, research in both areas.”

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

Ultra-Sensitive, Deformable, and Transparent Triboelectric Tactile Sensor Based on Micro-Pyramid Patterned Ionic Hydrogel for Interactive Human–Machine Interfaces by Kai Tao, Zhensheng Chen, Jiahao Yu, Haozhe Zeng, Jin Wu, Zixuan Wu, Qingyan Jia, Peng Li, Yongqing Fu, Honglong Chang, Weizheng Yuan. Advanced Science Volume 9, Issue 10 April 5, 2022 2104168 DOI: https://doi.org/10.1002/advs.202104168 First published: 31 January 2022

This paper is open access.

Cellulose-based nanogenerators to power biomedical implants?

This cellulose nanogenerator research comes from India. A Jan. 27, 2016 American Chemical Society (ACS) news release makes the announcement,

Implantable electronics that can deliver drugs, monitor vital signs and perform other health-related roles are on the horizon. But finding a way to power them remains a challenge. Now scientists have built a flexible nanogenerator out of cellulose, an abundant natural material, that could potentially harvest energy from the body — its heartbeats, blood flow and other almost imperceptible but constant movements. …

Efforts to convert the energy of motion — from footsteps, ocean waves, wind and other movement sources — are well underway. Many of these developing technologies are designed with the goal of powering everyday gadgets and even buildings. As such, they don’t need to bend and are often made with stiff materials. But to power biomedical devices inside the body, a flexible generator could provide more versatility. So Md. Mehebub Alam and Dipankar Mandal at Jadavpur University in India set out to design one.

The researchers turned to cellulose, the most abundant biopolymer on earth, and mixed it in a simple process with a kind of silicone called polydimethylsiloxane — the stuff of breast implants — and carbon nanotubes. Repeated pressing on the resulting nanogenerator lit up about two dozen LEDs instantly. It also charged capacitors that powered a portable LCD, a calculator and a wrist watch. And because cellulose is non-toxic, the researchers say the device could potentially be implanted in the body and harvest its internal stretches, vibrations and other movements [also known as, harvesting biomechanical motion].

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

Native Cellulose Microfiber-Based Hybrid Piezoelectric Generator for Mechanical Energy Harvesting Utility by
Md. Mehebub Alam and Dipankar Mandal. ACS Appl. Mater. Interfaces, 2016, 8 (3), pp 1555–1558 DOI: 10.1021/acsami.5b08168 Publication Date (Web): January 11, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

I did take a peek at the paper to see if I could determine whether or not they had used wood-derived cellulose and whether cellulose nanocrystals had been used. Based on the references cited for the paper, I think the answer to both questions is yes.

My latest piece on harvesting biomechanical motion is a June 24, 2014 post where I highlight a research project in Korea and another one in the UK and give links to previous posts on the topic.

Bendable, stretchable, light-weight, and transparent: a new competitor in the competition for ‘thinnest electric generator’

An Oct. 15, 2014 Columbia University (New York, US) press release (also on EurekAlert), describes another contender for the title of the world’s thinnest electric generator,

Researchers from Columbia Engineering and the Georgia Institute of Technology [US] report today [Oct. 15, 2014] that they have made the first experimental observation of piezoelectricity and the piezotronic effect in an atomically thin material, molybdenum disulfide (MoS2), resulting in a unique electric generator and mechanosensation devices that are optically transparent, extremely light, and very bendable and stretchable.

In a paper published online October 15, 2014, in Nature, research groups from the two institutions demonstrate the mechanical generation of electricity from the two-dimensional (2D) MoS2 material. The piezoelectric effect in this material had previously been predicted theoretically.

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

Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics by Wenzhuo Wu, Lei Wang, Yilei Li, Fan Zhang, Long Lin, Simiao Niu, Daniel Chenet, Xian Zhang, Yufeng Hao, Tony F. Heinz, James Hone, & Zhong Lin Wang. Nature (2014) doi:10.1038/nature13792 Published online 15 October 2014

This paper is behind a paywall. There is a free preview available with ReadCube Access.

Getting back to the Columbia University press release, it offers a general description of piezoelectricity and some insight into this new research on molybdenum disulfide,

Piezoelectricity is a well-known effect in which stretching or compressing a material causes it to generate an electrical voltage (or the reverse, in which an applied voltage causes it to expand or contract). But for materials of only a few atomic thicknesses, no experimental observation of piezoelectricity has been made, until now. The observation reported today provides a new property for two-dimensional materials such as molybdenum disulfide, opening the potential for new types of mechanically controlled electronic devices.

“This material—just a single layer of atoms—could be made as a wearable device, perhaps integrated into clothing, to convert energy from your body movement to electricity and power wearable sensors or medical devices, or perhaps supply enough energy to charge your cell phone in your pocket,” says James Hone, professor of mechanical engineering at Columbia and co-leader of the research.

“Proof of the piezoelectric effect and piezotronic effect adds new functionalities to these two-dimensional materials,” says Zhong Lin Wang, Regents’ Professor in Georgia Tech’s School of Materials Science and Engineering and a co-leader of the research. “The materials community is excited about molybdenum disulfide, and demonstrating the piezoelectric effect in it adds a new facet to the material.”

Hone and his research group demonstrated in 2008 that graphene, a 2D form of carbon, is the strongest material. He and Lei Wang, a postdoctoral fellow in Hone’s group, have been actively exploring the novel properties of 2D materials like graphene and MoS2 as they are stretched and compressed.

Zhong Lin Wang and his research group pioneered the field of piezoelectric nanogenerators for converting mechanical energy into electricity. He and postdoctoral fellow Wenzhuo Wu are also developing piezotronic devices, which use piezoelectric charges to control the flow of current through the material just as gate voltages do in conventional three-terminal transistors.

There are two keys to using molybdenum disulfide for generating current: using an odd number of layers and flexing it in the proper direction. The material is highly polar, but, Zhong Lin Wang notes, so an even number of layers cancels out the piezoelectric effect. The material’s crystalline structure also is piezoelectric in only certain crystalline orientations.

For the Nature study, Hone’s team placed thin flakes of MoS2 on flexible plastic substrates and determined how their crystal lattices were oriented using optical techniques. They then patterned metal electrodes onto the flakes. In research done at Georgia Tech, Wang’s group installed measurement electrodes on samples provided by Hone’s group, then measured current flows as the samples were mechanically deformed. They monitored the conversion of mechanical to electrical energy, and observed voltage and current outputs.

The researchers also noted that the output voltage reversed sign when they changed the direction of applied strain, and that it disappeared in samples with an even number of atomic layers, confirming theoretical predictions published last year. The presence of piezotronic effect in odd layer MoS2 was also observed for the first time.

“What’s really interesting is we’ve now found that a material like MoS2, which is not piezoelectric in bulk form, can become piezoelectric when it is thinned down to a single atomic layer,” says Lei Wang.

To be piezoelectric, a material must break central symmetry. A single atomic layer of MoS2 has such a structure, and should be piezoelectric. However, in bulk MoS2, successive layers are oriented in opposite directions, and generate positive and negative voltages that cancel each other out and give zero net piezoelectric effect.

“This adds another member to the family of piezoelectric materials for functional devices,” says Wenzhuo Wu.

In fact, MoS2 is just one of a group of 2D semiconducting materials known as transition metal dichalcogenides, all of which are predicted to have similar piezoelectric properties. These are part of an even larger family of 2D materials whose piezoelectric materials remain unexplored. Importantly, as has been shown by Hone and his colleagues, 2D materials can be stretched much farther than conventional materials, particularly traditional ceramic piezoelectrics, which are quite brittle.

The research could open the door to development of new applications for the material and its unique properties.

“This is the first experimental work in this area and is an elegant example of how the world becomes different when the size of material shrinks to the scale of a single atom,” Hone adds. “With what we’re learning, we’re eager to build useful devices for all kinds of applications.”

Ultimately, Zhong Lin Wang notes, the research could lead to complete atomic-thick nanosystems that are self-powered by harvesting mechanical energy from the environment. This study also reveals the piezotronic effect in two-dimensional materials for the first time, which greatly expands the application of layered materials for human-machine interfacing, robotics, MEMS, and active flexible electronics.

I see there’s a reference in that last paragraph to “harvesting mechanical energy from  the environment.” I’m not sure what they mean by that but I have written a few times about harvesting biomechanical energy. One of my earliest pieces is a July 12, 2010 post which features work by Zhong Lin Wang on harvesting energy from heart beats, blood flow, muscle stretching, or even irregular vibrations. One of my latest pieces is a Sept. 17, 2014 post about some work in Canada on harvesting energy from the jaw as you chew.

A final note, Dexter Johnson discusses this work in an Oct. 16, 2014 post on the Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website).

Batteryfree cardiac pacemaker

This particular energy-havesting pacemaker has been tested ‘in vivo’ or, as some like to say, ‘on animal models’. From an Aug. 31, 2014 European Society of Cardiology news release (also on EurekAlert),

A new batteryless cardiac pacemaker based on an automatic wristwatch and powered by heart motion was presented at ESC Congress 2014 today by Adrian Zurbuchen from Switzerland. The prototype device does not require battery replacement.

Mr Zurbuchen, a PhD candidate in the Cardiovascular Engineering Group at ARTORG, University of Bern, Switzerland, said: “Batteries are a limiting factor in today’s medical implants. Once they reach a critically low energy level, physicians see themselves forced to replace a correctly functioning medical device in a surgical intervention. This is an unpleasant scenario which increases costs and the risk of complications for patients.”

Four years ago Professor Rolf Vogel, a cardiologist and engineer at the University of Bern, had the idea of using an automatic wristwatch mechanism to harvest the energy of heart motion. Mr Zurbuchen said: “The heart seems to be a very promising energy source because its contractions are repetitive and present for 24 hours a day, 7 days a week. Furthermore the automatic clockwork, invented in the year 1777, has a good reputation as a reliable technology to scavenge energy from motion.”

The researchers’ first prototype is based on a commercially available automatic wristwatch. All unnecessary parts were removed to reduce weight and size. In addition, they developed a custom-made housing with eyelets that allows suturing the device directly onto the myocardium (photo 1).

The prototype works the same way it would on a person’s wrist. When it is exposed to an external acceleration, the eccentric mass of the clockwork starts rotating. This rotation progressively winds a mechanical spring. After the spring is fully charged it unwinds and thereby spins an electrical micro-generator.

To test the prototype, the researchers developed an electronic circuit to transform and store the signal into a small buffer capacity. They then connected the system to a custom-made cardiac pacemaker (photo 2). The system worked in three steps. First, the harvesting prototype acquired energy from the heart. Second, the energy was temporarily stored in the buffer capacity. And finally, the buffered energy was used by the pacemaker to apply minute stimuli to the heart.

The researchers successfully tested the system in in vivo experiments with domestic pigs. The newly developed system allowed them for the first time to perform batteryless overdrive-pacing at 130 beats per minute.

Mr Zurbuchen said: “We have shown that it is possible to pace the heart using the power of its own motion. The next step in our prototype is to integrate both the electronic circuit for energy storage and the custom-made pacemaker directly into the harvesting device. This will eliminate the need for leads.”

He concluded: “Our new pacemaker tackles the two major disadvantages of today’s pacemakers. First, pacemaker leads are prone to fracture and can pose an imminent threat to the patient. And second, the lifetime of a pacemaker battery is limited. Our energy harvesting system is located directly on the heart and has the potential to avoid both disadvantages by providing the world with a batteryless and leadless pacemaker.”

This project seems the furthest along with regard to its prospects for replacing batteries in pacemakers (with leadlessness being a definite plus) but there are other projects such as Korea’s Professor Keon Jae Lee of KAIST and Professor Boyoung Joung, M.D. at Severance Hospital of Yonsei University who are working on a piezoelectric nanogenerator according to a June 26, 2014 article by Colin Jeffrey for Gizmodo.com,

… Unfortunately, the battery technology used to power these devices [cardiac pacemakers] has not kept pace and the batteries need to be replaced on average every seven years, which requires further surgery. To address this problem, a group of researchers from Korea Advanced Institute of Science and Technology (KAIST) has developed a cardiac pacemaker that is powered semi-permanently by harnessing energy from the body’s own muscles.

The research team, headed by Professor Keon Jae Lee of KAIST and Professor Boyoung Joung, M.D. at Severance Hospital of Yonsei University, has created a flexible piezoelectric nanogenerator that has been used to directly stimulate the heart of a live rat using electrical energy produced from small body movements of the animal.

… the team created their new high-performance flexible nanogenerator from a thin film semiconductor material. In this case, lead magnesium niobate-lead titanate (PMN-PT) was used rather than the graphene oxide and carbon nanotubes of previous versions. As a result, the new device was able to harvest up to 8.2 V and 0.22 mA of electrical energy as a result of small flexing motions of the nanogenerator. The resultant voltage and current generated in this way were of sufficient levels to stimulate the rat’s heart directly.

I gather this project too was tested on animal models, in this case, rats.

Gaining some attention at roughly the same time as the Korean researchers, a French team’s work with a ‘living battery’ is mentioned in a June 17, 2014 news item on the Open Knowledge website,

Philippe Cinquin, Serge Cosnier and their team at Joseph Fourier University in France have invented a ‘living battery.’ The device – a fuel cell and conductive wires modified with reactive enzymes – has the power to tap into the body’s endless supply of glucose and convert simple sugar, which constitutes the energy source of living cells, into electricity.

Visions of implantable biofuel cells that use the body’s natural energy sources to power pacemakers or artificial hearts have been around since the 1960s, but the French team’s innovations represents the closest anyone has ever come to harnessing this energy.

The French team was a finalist for the 2014 European Inventor Award. Here’s a description of how their invention works, from their 2014 European Inventor Award’s webpage,

Biofuel cells that harvest energy from glucose in the body function much like every-day batteries that conduct electricity through positive and negative terminals called anodes and cathodes and a medium conducive to electric charge known as the electrolyte. Electricity is produced via a series of electrochemical reactions between these three components. These reactions are catalysed using enzymes that react with glucose stored in the blood.

Bodily fluids, which contain glucose and oxygen, serve as the electrolyte. To create an anode, two enzymes are used. The first enzyme breaks down the sugar glucose, which is produced every time the animal or person consumes food. The second enzyme oxidises the simpler sugars to release electrons. A current then flows as the electrons are drawn to the cathode. A capacitor that is hooked up to the biofuel cell stores the electric charge produced.

I wish all the researchers good luck as they race towards a new means of powering pacemakers, deep brain stimulators, and other implantable devices that now rely on batteries which need to be changed thus forcing the patient to undergo major surgery.

Self-powered batteries for pacemakers, etc. have been mentioned here before:

April 3, 2009 posting

July 12, 2010 posting

March 8, 2013 posting

Cardiac pacemakers: Korea’s in vivo demonstration of a self-powered one* 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.

* ‘one’ added to title on Aug. 13, 2014.

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.

Finger pinches today, heartbeats tomorrow and electricity forever

Devices powered by energy generated and harvested from one’s own body have been of tremendous interest to me. Last year I mentioned some research in this area by Professor Zhong Lin Wang at Georgia Tech (Georgia Institute of Technology) in a July 12, 2010 posting. Well, Wang and his team recently announced that they have developed the first commercially viable nanogenerator. From the March 29, 2011 news item on Physorg.com,

After six years of intensive effort, scientists are reporting development of the first commercially viable nanogenerator, a flexible chip that can use body movements — a finger pinch now en route to a pulse beat in the future — to generate electricity. Speaking here today at the 241st National Meeting & Exposition of the American Chemical Society, they described boosting the device’s power output by thousands times and its voltage by 150 times to finally move it out of the lab and toward everyday life.

“This development represents a milestone toward producing portable electronics that can be powered by body movements without the use of batteries or electrical outlets,” said lead scientist Zhong Lin Wang, Ph.D. “Our nanogenerators are poised to change lives in the future. Their potential is only limited by one’s imagination.”

Here’s how it works  (from Kit Eaton’s article on Fast Company),

The trick used by Dr. Zhong Lin Wang’s team has been to utilize nanowires made of zinc oxide (ZnO). ZnO is a piezoelectric material–meaning it changes shape slightly when an electrical field is applied across it, or a current is generated when it’s flexed by an external force. By combining nanoscopic wires (each 500 times narrower than a human hair) of ZnO into a flexible bundle, the team found it could generate truly workable amounts of energy. The bundle is actually bonded to a flexible polymer slice, and in the experimental setup five pinky-nail-size nanogenerators were stacked up to create a power supply that can push out 1 micro Amp at about 3 volts. That doesn’t sound like a lot, but it was enough to power an LED and an LCD screen in a demonstration of the technology’s effectiveness.

Dexter Johnson at Nanoclast on the IEEE (Institute of Electrical Engineering and Electronics) website notes in his March 30, 2010 posting (http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/powering-our-electronic-devices-with-nanogenerators-looks-more-feasible) that the nanogenerator’s commercial viability is dependent on work being done at the University of Illinois,

I would have happily chalked this story [about the nanogenerator] up to one more excellent job of getting nanomaterial research into the mainstream press, but because of recent work by Eric Pop and his colleagues at the University of Illinois’s Beckman Institute in reducing the energy consumed by electronic devices it seems a bit more intriguing now.

So low is the energy consumption of the electronics proposed by the University of Illinois research it is to the point where a mobile device may not need a battery but could possibly operate on the energy generated from piezoelectric-enabled nanogenerators contained within such devices like those proposed by Wang.

I have a suspicion it’s going to be a while before I will be wearing nanogenerators to harvest the electricity my body produces. Meanwhile, I have some questions about the possible uses for nanogenerators (from the Kit Eaton article),

The search for tiny power generator technology has slowly inched forward for years for good reason–there are a trillion medical and surveillance uses–not to mention countless consumer electronics applications– for a system that could grab electrical power from something nearby that’s moving even just a tiny bit. Imagine an implanted insulin pump, or a pacemaker that’s powered by the throbbing of the heart or blood vessels nearby (and then imagine the pacemaker powering the heart, which is powered by the pacemaker, and so on and so on….) and you see how useful such a system could be.

It’s the reference to surveillance that makes me a little uneasy.

Harvesting biomechanical energy

Even before noting the vampire battery work being done at the University of British Columbia (April 3, 2009) , I’ve been quite interested in self-powered batteries. (As for why it’s a ‘vampire’, researchers are working on a battery fueled by by a patient’s own blood so that theoretically someone with a pacemaker or a deep brain stimulator would require fewer battery changes, i.e., fewer operations.)

Professor Zhong Lin Wang at Georgia Tech (Georgia Institute of Technology in the US) is taking another approach to self-powered batteries by harvesting irregular mechanical motion (such as heart beats, finger tapping, breathing, vocal cord vibrations, etc.) in a field that’s been termed nanopiezotronics. Michael Berger at Nanowerk has written an article spotlighting Professor Wang’s work and its progress. From the article,

“Our experiments clearly show that the in vivo application of our single-wire nanogenerator for harvesting biomechanical energy inside a live animal works,” says Wang. “The nanogenerator has successfully converted the mechanical vibration energy from normal breathing and a heartbeat into electricity.”

He concludes that his team’s research shows a feasible approach to scavenge the biomechanical energy inside the body, such as heart beat, blood flow, muscle stretching, or even irregular vibration. “This work presents a crucial step towards implantable self-powered nanosystems.”

There’s still a lot of work to be done before human clinical trials (let alone thinking about products in the marketplace),

…  Wang 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.”

If you’re interested in the details about what the researchers are doing, please do read Berger’s fascinating investigation into the area of research.