Energy harvesting study on single and multilayer ferroelectret foams under compressive force

Luo, Zhenhua; Zhu, Dibin; Shi, Jindan; Beeby, Steve; Zhang, Chunhong; Proynov, Plamen; Stark, Bernard H.

doi:10.1109/tdei.2015.7116323

Cited by 42 publications

(34 citation statements)

References 45 publications

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“…In contrast to conventional energy harvesting systems, the pro- posed step counter removes the energy storage element and operates directly from the harvesting source ( Figure 1). It sustains its operation by harvesting energy from footsteps, using a ferroelectret insole which generates electricity under mechanical stress [8]. The system uses a microcontroller (MCU), with a low-power non-volatile memory, which wakes up at each step and retains data during the power outage between steps.…”

Section: Introductionmentioning

confidence: 99%

Intermittently-powered energy harvesting step counter for fitness tracking

Rodríguez

Balsamo

Luo

et al. 2017

2017 IEEE Sensors Applications Symposium (SAS)

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Abstract-Over the past decade, there has been a rapid increase in the popularity of wearable and portable devices, such as step counters, to monitor fitness performance. However, these devices are battery-powered, meaning that their lifetimes are restricted by battery capacity. Ideally, wearable devices could be powered by energy harvested from human motion. Energy harvesting systems traditionally incorporate energy storage to cope with source variability. However, energy storage takes time to charge and increases the size and cost of systems. This paper proposes an intermittently-powered energy harvesting step counter for integrated wearable applications, which aims to remove the energy storage element. The proposed step counter sustains its operation by harvesting energy from footsteps using a ferroelectret insole, which also works as an event detection sensor, i.e. the system is powered by the parameter that is being sensed. Designing this required the characterization of the insole to evaluate the amount of energy provided, and analysis of the energy needed by the overall system. Finally, the system was implemented and experimentally validated. The proposed step counter has an error of less than 4% when walking, which is lower than the error in conventional smartphone applications.

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Section: Introductionmentioning

confidence: 99%

Intermittently-powered energy harvesting step counter for fitness tracking

Rodríguez

Balsamo

Luo

et al. 2017

2017 IEEE Sensors Applications Symposium (SAS)

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“…[7][8][9][10][11][12][13][14] Piezoelectrets are charged polymer foams exhibiting strong piezoelectric effects, small bulk density, flexibility or/and stretchability. 15,16 The quasistatic piezoelectric d 33 coefficients of piezoelectrets can be up to a few hundred pC/N in polypropylene (PP) films [17][18][19][20][21][22][23] and are of similar size or larger in some fluorocarbon polymer films, /ε 0 ε r (see also Sect.…”

Section: Introductionmentioning

confidence: 99%

Energy harvesting from vibration with cross-linked polypropylene piezoelectrets

Zhang

Sessler

2015

AIP Advances

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Piezoelectret films are prepared by modification of the microstructure of polypropylene foam sheets cross-linked by electronic irradiation (IXPP), followed by proper corona charging. Young’s modulus, relative permittivity, and electromechanical coupling coefficient of the fabricated films, determined by dielectric resonance spectra, are about 0.7 MPa, 1.6, and 0.08, respectively. Dynamic piezoelectric d33 coefficients up to 650 pC/N at 200 Hz are achieved. The figure of merit (FOM, d33 ⋅ g33) for a more typical d33 value of 400 pC/N is about 11.2 GPa−1. Vibration-based energy harvesting with one-layer and two-layer stacks of these films is investigated at various frequencies and load resistances. At an optimum load resistance of 9 MΩ and a resonance frequency of 800 Hz, a maximum output power of 120 μW, referred to the acceleration g due to gravity, is obtained for an energy harvester consisting of a one-layer IXPP film with an area of 3.14 cm2 and a seismic mass of 33.7 g. The output power can be further improved by using two-layer stacks of IXPP films in electric series. IXPP energy harvesters could be used to energize low-power electronic devices, such as wireless sensors and LED lights.

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“…10 The oscilloscope has an internal resistance of 1 MΩ which 11 is treated as the load resistance of the ferroelectret energy 12…”

Section: Experimental Results 82mentioning

confidence: 99%

“…Since = ɛ 33 ℎ− ℎ in Figure 3 Since the output electrical signal is a sinusoidal pulse or a 50 trapezoidal pulse closed to sinusoidal shape [10], Vout can 51 be calculated as…”

Section: Introduction 19mentioning

confidence: 99%

An electromechanical model of ferroelectret for energy harvesting

Luo

Zhu

Beeby

2016

Smart Mater. Struct.

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Ferroelectret is a cellular polymer foam that is able to convert compressive and bending forces into electrical signals, which 10 can be used for both sensing and energy harvesting. In the past several research groups have proposed theoretical models that 11 relate the output voltage of the ferroelectret to its mechanical deformation. This is particularly useful for sensing applications 12where the signal-to-noise ratio is important. However, for energy harvesting applications, a theoretical model needs to include 13 both the voltage across a resistive load and the duration of the electrical signal as energy is an integral of power over time. In 14 this work, we propose a theoretical model that explains the behaviour of a ferroelectret when used as an energy harvester. This 15 model can be used to predict the energy output of a ferroelectret by knowing its parameters, and therefore optimize the harvester 16 design for specific energy harvesting application. 17 18 Introduction 19A ferroelectret is a thin and flexible porous polymer 20 that can store positive and negative charges in its internal 21 voids after charging. It is then able to convert compressive 22 and bending forces into electrical signals that can be used 23 for both sensing and energy harvesting [1][2][3][4][5][6][7][8][9][10]. Our 24 previous study has demonstrated that the output energy 25 from porous polypropylene (PP) ferroelectret is sufficient 26 to power a low-power wireless sensor chipset [10]. When 27 a ferroelectret is used in energy harvesting applications, its 28 output pulses can be used to charge an energy storage 29 device, such as a capacitor, to store the energy that 30 generated from the mechanical deformation. This is 31 similar in principle to piezoelectric energy harvesting 32 using piezo ceramics [11, 12]. However, ferroelectret 33 materials are flexible and therefore more attractive for 34 wearable applications. 35When ferroelectret is used as the sensing material in a 36 sensor, the magnitude of the output voltage and the signal-37 to-noise ratio are the key design parameters [8,13]. 38 Previous studies [3,[14][15][16] To predict the output energy of a ferroelectret, we 82 propose an electromechanical model that treats the 83 ferroelectret as both a capacitor and a spring-mass-damper 84 system. In this model a ferroelectret can be treated as a 85 capacitor with internal spring that provides restoring force 86 when the applied compressive force is released. 3, 28], its 2 capacitance C will increase as the thickness reduces when 3 a compressive force is applied. Using 33 = and = 4 , the Vout of the ferroelectret can be expressed as 5output voltage when compressed. When the ferroelectret is 1 treated as a capacitor containing charge [where C is the capacitance of the ferroelectret when 7 compressed. Since = ɛ 33 ℎ− ℎ in Figure 3, Eq.(1) can 8 be derived into 9where ɛ33 is the permittivity of the material. Using Eq. (2), 11the Vout of a ferroelectret can be related to its dimensional 12 parameters (b, l, h), thickness deforma...

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Energy harvesting study on single and multilayer ferroelectret foams under compressive force

Cited by 42 publications

References 45 publications

Intermittently-powered energy harvesting step counter for fitness tracking

Intermittently-powered energy harvesting step counter for fitness tracking

Energy harvesting from vibration with cross-linked polypropylene piezoelectrets

An electromechanical model of ferroelectret for energy harvesting

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