Pacemaker that uses the heart to generate its own electricity and doesn’t need batteries – Daily Mail


A revolutionary battery-free pacemaker capable of making its own electricity from the heart’s movement has been created. 

It works using an ‘energy harvester’ – known as an iTENG – wrapped around the heart that generates electricity as the heart contracts and relaxes during pumps.

The device harvests energy and stores it in a ‘power management unit’ in a capacitor which is then used to power the pacemaker itself.

With each beat of the heart, more electricity is produced to power the pacemaker. 

It device could spell the end of regular surgical procedures to replace the battery-reliant devices and make pacemakers more durable, long-lasting and effective. 

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A pacemaker which doesn’t need batteries would be powered by the heart itself. A prototype was built and worked perfectly after scientists applied a patch called the iTENG (pictured) to the heart to create its own electricity which was then used to power a pacemaker 

The way it operates within the body led to the device being dubbed a ‘symbiotic cardiac pacemaker’ (SCP). It is made of three parts – an energy harvesting unit called the iTENG, a power management unit made of a capacitor and the pacemaker itself (pictured) 

The implant was fitted to an adult pig and was successful in controlling heart rhythm. 

It also corrected serious conditions such as sinus arrhythmia which causes it to skip beats and ventricular fibrillation that makes it race – both are potentially fatal.

Pigs were used in the tests due to their similarity in size and function to that of humans. 

The way it operates within the body led to the device being dubbed a ‘symbiotic cardiac pacemaker’ (SCP). 

It is made of three parts – an energy harvesting unit called the iTENG, a power management unit made of a capacitor and the pacemaker itself. 

The iTENG is made of two layers separated by a sponge-like filling which traps electrons as the heart enlarges and contracts during pumping. 

These are then stored in the capacitor which releases the energy to power the pacemaker.  

Existing pacemakers are roughly the size of a matchbox and are placed in the chest cavity to control abnormalities in how a heart beats. 

They are currently powered by small batteries which trigger the heart to beat at the correct moment. 

Battery life means the patient has to have a new pacemaker fitted every five to 12 years. 

A host of research has gone into the possibility of battery-free devices and this prototype, developed by a team of American and Chinese scientists, led by Dr Zhong Lin Wang from the Georgia Institute of Technology in the US, may be the most promising breakthrough yet.  

It is based on a phenomenon called triboelectricity, which is similar to static electricity and is the same effect that can cause a tiny electric shock, when touching a doorknob, for instance. 

The iTENG is driven by the diastole and systole of the heart. The movement of the two layers apart creates the triboelectric effect – effectively a contained and channelled form of static electricity. This traps electrons and creates a potential difference to power the pacemaker 

The iTENG implantation process in animal experiments done on pigs due to their similarity in size, structure and function to that of a human organ 

HOW DOES THE BATTERY-FREE PACEMAKER WORK?

It is being dubbed as an implanted symbiotic pacemaker (SPM) which consists of three parts: the energy harvest unit (iTENG), power management unit (PMU), and pacemaker unit.

The energy harvest unit (iTENG) 

The iTENG is a flexible patch which harvests the heart’s energy. 

It is made from two layers and has a space between them to encourage the triboelectric effect to take place.

This is then wrapped in a Teflon layer to protect it from any liquid damage in the body.

It is constantly electrified as electrons pass through the material and creates an electric potential between the two layers.

It is placed between the heart and pericardium – the outer membrane encasing the heart – on the left ventricle

Power Management Unit (PMU)

The electrical energy generated by iTENG is stored in a 100 μF capacitor.

It is off originally and energy is stored in the capacitor. The switch was turned on by a magnet acting as a wireless passive trigger.

This releases the energy and drives the pacemaker to produce electrical pulses and control the rate of contraction.

Batteryless pacemaker

A pacemaker which is similar in size and function is joined to the power source and has no batteries.

The pulses from the pacemaker induce contraction and regulate heart rate through electrodes.

The voltage and duration of the electrical pulses were 3 V and 0.5 ms, respectively.

Rate of the electrical pulses was preset to 130 bpm, in consideration of the high heart rate of the pig during the experiment.

It is being dubbed as an implanted symbiotic pacemaker (SPM) which consists of three parts: the energy harvest unit (iTENG), power management unit (PMU), and pacemaker unit

Tests showed that the harvested energy was more than enough to power a human pacemaker as it reached a maximum of  height of 65.2V.

Each cycle made .495 micro joules (μJ) – far more than the 0.377μJ minimum threshold required for the pacemaker to function.  

However, it could be some years before these symbiotic pacemakers are ready to be implanted safely into human patients as the feasibility and safety requires extensive testing. 

British expert Tim Chico, professor of cardiovascular medicine at the University of Sheffield, said: ‘The study results are very encouraging but there is a lot of work to be done before it might be used in humans. 

‘The energy harvest device needed to be inserted around the heart in open heart surgery, which is a lot more invasive than is needed for current pacemakers and would greatly limit who could have this. 

‘However, the device could use movement from other muscles rather than the heart, so this should not be a problem.

‘People who need the pacemaker to work a lot or all of the time, or to deliver defibrillation, use a lot more electricity and so it is important that any self-powering device has enough stored energy for these situations.’ 

The iTENG is a flexible patch which harvests the heart’s energy. It is made from two layers and has a sponge-like spacer between them to encourage the triboelectric effect to take place. This is then wrapped in a Teflon layer to protect it from any liquid damage in the body. There are several components making up these individual layers for the patch (pictured)

The electrical energy generated by iTENG is stored in a 100 μF capacitor in the PMU. It is off when installed and energy is stored in the capacitor. The switch is turned on by a magnet acting as a wireless trigger. This releases the energy and drives the pacemaker to produce electrical pulses and control the rate of contraction (pictured, a schematic of the wireless activation) 

WHAT IS THE TRIBOELECTRIC EFFECT?

The triboelectric effect is a form of electrification which occurs in some materials. 

The materials have two layers which can be pulled apart and become electrically charged when they are.   

It has its foundations in static electricity, where to materials when rubbed together interact and electrons are exchanged. This creates a small voltage. 

For example, the rubbing of a balloon on hair exchange electrons, making both sides slightly charged. This can then attract hair and cause it to stick to the balloon as the positive and negatively charged ends attract. 

The more the two layers of the triboelectric effect interact and come into physical contact with each other the greater the exchange of electrons and the larger the electrical potential that is created.    

Dr Zhong Lin Wang said: ‘Current pacemakers and other implantable medical devices are powered by batteries that are bulky, rigid, and short-lived.

‘Self-powered implantable medical electronic devices that harvest biomechanical energy from cardiac motion, respiratory movement and blood flow are part of a paradigm shift that is on the horizon.

‘Here, we demonstrate a fully implanted symbiotic pacemaker based on an implantable triboelectric nanogenerator, which achieves energy harvesting and storage as well as cardiac pacing on a large-animal scale.

‘The symbiotic pacemaker successfully corrects sinus arrhythmia and prevents deterioration.’

Professor Chico said: ‘The present study hopes to get rid of the need for battery replacement by developing a self-powering pacemaker.’

‘The study results are very encouraging but there is a lot of work to be done before it might be used in humans.

‘The energy harvest device needed to be inserted around the heart in open heart surgery, which is a lot more invasive than is needed for current pacemakers and would greatly limit who could have this.

‘However, the device could use movement from other muscles rather than the heart, so this should not be a problem.

‘People who need the pacemaker to work a lot or all of the time, or to deliver defibrillation use a lot more electricity and so it is important that any self-powering device has enough stored energy for these situations.’ 

The full paper was published in the journal Nature Communications.   

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