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H

arvesting energy from ambient sources in our

environment has generated tremendous interest as it

offers a fundamental energy solution for ‘small power’

applications, including, but not limited to, ubiquitous wireless

sensor nodes; portable, flexible and wearable electronics;

biomedical implants and structural/environmental monitoring

devices. As an example, consider that the number of smart

devices linking everyday objects via the internet is estimated to

grow to 50 billion by the year 2020. Most of these Internet of

Things (IoT) devices will be extraordinarily small and most likely

embedded, and will wirelessly provide useful data that will make

our lives easier, better and more energy efficient. The only

sustainable way to power them is using ambient energy

harvesting that lasts throughout the lifetime of the product.

Vibrational energy harvesting

Energy harvesting from ambient vibrations is particularly attractive

as these are ever present and easily accessible, originating from

sources such as moving parts of machines, fluid flow and even

body movements. Indeed, we are at a unique stage in the

evolution of modern electronics where the power consumption of

devices has been reduced to such an extent that it is now feasible

to power them from ubiquitous small scale vibrations in the

environment. The time is thus ripe for innovative ways to develop

and exploit this vital technology towards next-generation self-

powered electronics.

In this context, piezoelectric materials offer the simplest means of

directly converting mechanical vibrations into electrical power and

are well suited for microscale device applications, thus offering a

means of superseding traditional power sources such as batteries

that require constant replacing/recharging and that do not scale

easily with size. In particular, nanoscale piezoelectric energy

harvesters, or nanogenerators, are capable of converting small

ambient vibrations into electrical energy, thus paving the way for

the realisation of the next generation of self-powered devices, with

profound implications in far-reaching areas such as smart city

planning, health, robotics, environmental and structural

monitoring, resource management and sustainable development.

Review

A recent review article from our group

1

highlighted the fact that

nanogenerator research to date has mainly focused on

traditional piezoelectric materials in the form of ceramics, but

these are stiff and prone to mechanical failure. On the other

hand, piezoelectric polymers, although less well studied, have

several advantages over ceramics such as being flexible, robust,

lightweight, easy and cheap to fabricate, lead free and bio

compatible. However, they do suffer from inferior piezoelectric

properties in comparison to ceramics.

As such, while the field of piezoelectric nanogenerators has

witnessed tremendous growth over the last few years, it is

dominated by ceramics such as zinc oxide, with research in

polymer nanogenerators remaining limited and restricted to just

one family of polymers, namely polyvinylidene-fluoride and its

copolymers. This field currently faces orthogonal difficulties

associated with these two classes of materials. In order to move

forward, our group aims to develop novel hybrid polymer-ceramic

nanocomposites combining the best of both materials.

Such hybrid systems offer plenty of scope for innovation, and

thus our strategy involves combining i) materials engineering

to create novel piezoelectric hybrid nanomaterials with

enhanced energy harvesting functionalities; ii) state-of-the art

nanoscale characterisation to explore and exploit these novel

materials; and iii) fabrication of high performance

nanogenerators for implementation into commercial devices

using insight gained from the computational modelling of

materials and device parameters.

Energy harvesting from small scale ambient vibrations in the environment could

pave the way for autonomous electronic devices

Small power, big impact

52

I S S U E S E V E N

H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L

www.horizon2020projects.com

P R O F I L E

S P E C I A L F E AT U R E : M AT E R I A L S

Energy harvesting from ambient vibration sources for self-powered

micro/nanoelectronic devices