Performance comparison of PZT and PMN–PT piezoceramics for vibration energy harvesting using standard or nonlinear approach

Sensors and Actuators A 163 (2010) 493–500

Contents lists available at ScienceDirect

Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna

Performance comparison of PZT and PMN–PT piezoceramics for vibration energy harvesting using standard or nonlinear approach Prissana Rakbamrung a , Mickaël Lallart b,∗ , Daniel Guyomar b , Nantakan Muensit a , Chanchana Thanachayanont c , Claude Lucat d , Benoît Guiffard b , Lionel Petit b , Pisan Sukwisut a a

Department of Physics, Prince of Songkla University, Songkhla, Thailand LGEF, INSA-Lyon, 8 rue de la Physique, F-69621, Lyon, France National Metals and Materials Technology Center, Pathumthanee, Thailand d Laboratoire IMS, Université de Bordeaux I, Talence 33405, France b c

a r t i c l e

i n f o

Article history: Received 15 February 2010 Received in revised form 18 August 2010 Accepted 18 August 2010

Keywords: Energy harvesting Energy scavenging Piezoelectric Nonlinear Energy conversion PMN–PT PZT

a b s t r a c t This paper reports the performance comparison of two common piezoelectric compositions for energy harvesting purposes, using either a standard or a nonlinear technique. Unlike single crystals, piezoelectric ceramics are quite easy to obtain, and thus their application to realistic applications is feasible. This study focuses on two compositions: PZT + 1 mol% Mn and PMN–25PT, obtained from sintering piezoelectric powders, and highlights the advantages and drawbacks for each of them. Then the obtained samples are evaluated for energy harvesting purposes, either by connecting them directly to the harvesting stage or by adding a nonlinear interface that consists of inverting the piezovoltage synchronously with the structure motion, leading to an artificial increase of the conversion abilities. The piezoceramics show a significant difference in power generation ability when using the classical energy harvesting technique. However, it is demonstrated that the use of the nonlinear treatment on the output voltage of the transducers leads to a great reduction in this discrepancy in spite of the difference in ceramic compositions. © 2010 Elsevier B.V. All rights reserved.

1. Introduction The proliferation of lightweight, portable devices has led to the challenge of supplying electrical energy to these systems [1–4]. Up to now, such an issue has been overcome by the use of primary batteries, that however features maintenance problems due to their limited lifespan, as well as environmental issues because of their complex recycling process. Hence, in order to counteract these problems, the use of microgenerators able to convert ambient energy into useful electrical energy has been proposed and investigated over the last decade. Among the available energy sources (for instance thermal or solar), a particular attention has been placed on vibration energy harvesting using piezoelectric elements for the conception of small-scale harvesters [5–7], as these materials feature high energy densities and high integration potentials. The maximization of the output power of such microgenerators is usually obtained by using piezomaterial featuring high coupling coefficient along the 3–1 axis (flexural mode). Hence, a

∗ Corresponding author. Tel.: +33 472437428. E-mail address: [email protected] (M. Lallart). 0924-4247/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2010.08.028

great effort has been made in past few years in the field of piezoelectric single crystals featuring giant piezoelectric properties [8]. Nevertheless, the conception of such materials is complex and costly, and no industrial process exists up to now. Hence, piezoceramics that can feature a much easier fabrication process have been of interest. These include the lead zirconate titanate or PZT ceramic which is well known for various applications, including energy harvesting devices [9]. A small amount of various acceptor dopants such as Mn are sometimes added during the fabrication process in order to enhance its piezoelectric properties. In this domain, it has been reported that the reduction of oxygen vacancy concentration and improvements in PZT fatigue and retention characteristics are obtained when small amount of Mn (<1 mol%) is doped into PZT making the PZT + 1 mol% Mn a good trade-off for piezoelectric conversion [10,11]. Another composition of interest is the PT-doped PMN, as such a ceramic is a relaxor-based ferroelectric with excellent electromechanical coupling. Compared to PZT, the piezoelectric coefficient of such materials can be increased by a factor up to 3 in lateral mode and exceed 2000 pC N−1 [12,13]. PT is interesting to use as dopant of PMN to adjust the Curie temperature (TC ) of the sample due to the fact that the polarization is disappearing over TC . While it has been reported in previous works that the PMN–35PT ceramic exhibits the highest piezoelectric activity

494

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

[14], the presence of two phases in this composition (rhombohedral and tetragonal) may induce some instabilities in terms of temperature or stress (because of a possible phase transition), as well as a hysteretic behavior. Contrarily, PMN–25PT is purely rhombohedral, and, although having lower piezoelectric coefficients, is a good trade-off for realistic applications. The sintering of this composition is easier as well. Another approach for artificially enhancing the conversion abilities of piezoelectric materials has been proposed by Guyomar et al. [15], and consists of intermittently connecting the piezoelectric element on a resonant network synchronously with the structure motion, leading to the concept of the so-called Synchronized Switch Harvesting on Inductor (SSHI) technique. Such an approach therefore allows shifting and increasing the piezovoltage, resulting in higher conversion abilities. Several architectures derived from this concept have been developed, aiming at reducing the load dependence [16,17], increasing the operational bandwidth, diminishing the effect of discrete components and losses [18,19] or extending the concept to other conversion effects [20], but the physical principles for enhancing the conversion abilities of the material remain the same. The purpose of this paper lies in the comparison of the performance of the two commonly used piezoceramic compositions exposed above and their application to energy harvesting. In this latter case, two approaches will be considered: either the microgenerator features standard energy harvesting interface, or the nonlinear technique is included. Hence, a general comparison chart will be derived, showing the difference between the piezoceramic composition when using or not the switching interface. The paper is organized as follows. Section 2 deals with the material aspects of the study, exposing the synthesis procedure and piezoelectric characteristics of the investigated composition. Then Section 3 will present the application of the obtained material for energy harvesting purpose, as well as a performance comparison of the harvester featuring standard electrical interface or switching interface. Implementation issues, cost and complexity are also discussed in the section. Finally, Section 4 briefly concludes the paper, recalling the main results obtained by this study. 2. Material aspects 2.1. Synthesis procedure For the investigation of vibration energy harvesting, the two common compositions discussed above were chosen: PZT with a Zr/Ti ratio of 52/48 with an introduction of 1 mol% Mn, and 0.75Pb(Mg1/3 Nb2/3 )O3 –0.25PT (abbreviated PMN–25PT). The samples were fabricated using solid-state route as described in [21,22]. Mn-doped PZT ceramic was prepared by coprecipitation of oxalates and hydroxides and dried at 100 ◦ C for 10 h, whereas the PMN–PT was prepared with stoichiometric proportions using a two stage synthesis process under air. The sintering temperature for both compositions is 1230 ◦ C during 120 min. After the sintering process, the average thickness and diameter of all the samples were about 1 mm and 14 mm, respectively. 2.2. Characterization procedure For the analysis of phase content the sintered bodies were checked by X-ray powder diffraction (XRD, Philips X’PertMPD, Nifiltered CuK␣ radiation) to identify the desired perovskite phase without pyrochlore. Prior to measurements, each disk-like sample was poled under the same condition regardless of the different thicknesses and compositions. The poling procedure used a DC electric field of 2.5 kV mm−1 in silicone oil for 2 min at a temperature of

Fig. 1. XRD pattern of PZT + 1 mol% Mn and PMN–25PT samples.

120 ◦ C and 50 ◦ C for PZT + 1 mol% Mn and PMN–25PT, respectively. The poling field was chosen to be close to the coercive field, ensuring a maximal remnant polarization (it has been demonstrated in [23] that for higher electric fields, the remnant polarization does not increase any longer), and the temperature has been determined to increase the mobility of the dipoles without compromising the poling procedure by ensuring a temperature much less than the Curie point. From the poling temperature, the poling time has been chosen to ensure a good alignment of the dipoles. The microstructures of the as-sintered surfaces of the samples were imaged using scanning electron microscopy (SEM, JeolJSM-5800LV). Electrical measurement was made on ceramics with density that was about 1.8 g cm−3 . To investigate electrical properties, silver past was deposited on both sides of the surfaces of the disc samples. The capacitance and dissipation factor (D) of the samples were measured using a high precision LCR meter (Hewlett Packard 4284A) at 1 kHz from which the dielectric constant was calculated. The piezoelectric strain coefficient was determined using a Berlincourt meter. An impedance analyzer (Hewlett Packard 4194A) with a frequency range of 100–40 MHz was used to determine the resonance frequency of all the samples. All measurements were performed in room condition.

2.3. Results and discussion As the first investigation, the XRD patterns of the two piezoceramics could be well identified to be a standard perovskite structure (Fig. 1). In particular, the peak at 2 = 31◦ corresponds to the (1 1 0) plane, that exhibited a tetragonal symmetry of a perovskite crystal. In the XRD pattern of the PZT–1 mol% Mn, no pyroclore phase was found though the pattern of the PMN–25PT showed a small amount of pyroclore. A volume percentage of the perovskite phase for each composition was calculated from Eq. (1) and it was found to be higher than 90% for both samples. Perovskite(%) =

Iperov × 100%. Iperov + Ipyro

(1)

Fig. 2 shows the SEM micrographs of the morphology of the piezoceramics. The PT and Mn, respectively, introduced in PMN and PZT systems resulted in differences in shape and average grain size of the samples. It can be seen clearly that the PMN–25PT has regular cubic grains and the Mn-doped PZT has smaller grains with a combination of different shapes. A summary of the properties for both compositions is shown in Table 1. A relatively dense morphology and regular grain patterns of the PMN–25PT led to higher values of piezoelectric coefficient d33 , mechanical quality factor QM and squared coupling coefficient k2 . It should be a better choice of piezoceramic samples for energy harvesting applications. However, the performance in terms of energy harvesting for both compositons is analysed in the next section.

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

495

Fig. 2. SEM micrographs of (a) PMN–25PT and (b) PZT + 1 mol% Mn samples.

Table 1 Summary of the various properties of piezoceramic samples. Sample

εT33 (nF m−1 ) (1 kHz)

tanı (1 kHz)

d33 (pC N−1 )

−d31 (pm V−1 )

QM

k2

E s11 (×10−12 m2 N−1 )

PMN–25PT PZT + 1 mol% Mn

1.88 6.53

0.0267 0.0249

235 145

17 53

127.5 197

0.11 0.02

15.174 24.752

3. Application to energy harvesting

cient and short-circuit stiffness of the structure, while ˛ and C0 are given as the force factor and clamped capacitance, respectively.

The purpose of this section is to evaluate the performance of the previously presented piezoceramic samples for energy harvesting. Each sample is bonded on a spring steel cantilever beam whose dimensions are 55 × 17 × 0.5 mm3 , and featuring a 6 × 6 × 2.5 mm3 magnetic tip mass of 0.78 g, as depicted in Fig. 3. Hence, in the following, the analysis will be done considering the whole electromechanical device made of the beam, the piezoelectric material and the tip mass. 3.1. Energy harvesting basics Before assessing the energy harvesting abilities of the considered samples, this part aims at recalling the basic operations of energy harvesting interfaces in steady state at the resonance frequency, as well as the main results obtained in terms of harvested power [16]. The following developments are based on a simple but realistic single degree of freedom (SDOF) model of the electromechanical structure (Fig. 4), leading to the governing motion and electrical equations [24]:



M u¨ + C u˙ + KE u = F − ˛V , I = ˛u˙ − C0 V˙

(2)

where u, F, V and I refer to the beam displacement, applied force, piezoelectric voltage and current flowing out of the piezoelement. M, C and KE denote the dynamic mass, structural damping coeffi-

3.1.1. Standard interface The simplest way of extracting energy from a piezoelectric material consists of directly connecting the electrodes of the active element to a smoothing capacitor and a load through a rectifier bridge (Fig. 5(a)). In this case the energy harvesting process occurs when the absolute value of the piezovoltage equals the rectified voltage VDC (Fig. 5(b)). The remaining of the time, the piezoelectric insert is left in open circuit. Assuming that the storage/smoothing capacitor CS is relatively large (CS  C0 and RL CS  T/2, with T the vibration period) so that the rectified voltage VDC may be considered as constant, the harvested energy Estand per harvesting cycle is then given by integrating the product of the current by the rectified voltage:



t2

Estand =

VDC Idt,

(3)

t1

with t1 and t2 the time instants when the conduction starts and stops, respectively (the end of the conduction corresponds to the cancellation of the current, which actually occurs when the displacement is maximal). In this case, it can be shown that the expression of the power yields [16]: Pstand = 4f0 VDC (˛uM − C0 VDC ),

(4)

with f0 the vibration frequency and uM the displacement magnitude. However harvesting energy from an electromechanical structure leads to a decrease of the mechanical energy, and therefore

Fig. 3. Energy harvesting structure and experimental set-up.

Fig. 4. Electromechanical SDOF model of the structure.

496

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

(b) Magnitude (a.u.)

Displacement Piezovoltage Rectified voltage Current

(a)

1

2

0

T/2

t

1

T/2+t

1

T

Time (a.u.) Fig. 5. Standard energy harvesting interface: (a) schematics; (b) waveforms: (1): open circuit; (2) harvesting process.

Displacement Piezovoltage Rectified voltage Current

(b) 2 1

V

DC

3

(a)

−γ V

DC

t

t

1

t2

Fig. 6. Parallel SSHI energy harvesting interface: (a) schematics; (b) waveforms: (1): open circuit; (2) harvesting process; (3) voltage inversion.

induces damping effect, leading to the expression of the harvested power as a function of the input force [16]:



2

Pstand =

16f0 ˛2 RL (1 + 4f0 RL C0 )

2

2

FM 2

2Cf0 + (16f0 ˛2 RL /(1 + 4f0 RL C0 ) )

 = e−(/2Qi ) , , (5)

whose maximum value as a function of the figure of merit given by the product of the squared coupling coefficient k2 by the mechanical quality factor QM 1 whose expression is given by: 2

k QM

˛2 = C0 C

yields [20]:

 Pstand 

max

=



⎧ ⎪ ⎨ ⎪ ⎩

M , KE + (˛2 /C0 )

2  FM ( + k2 QM ) 2 C 2 FM

k2 QM

2

8C

(6)

for k2 QM ≤  .

to an imperfect voltage inversion, characterized by the inversion coefficient  defined as:

with Q i the electrical quality factor of the inversion circuit (Qi = √ L/(R C0 )). Because of the cumulative effect of the voltage inversion, the switching process leads to a great increase of the voltage, as well as a reduction of the delay between the voltage and the velocity (Fig. 6(b)), denoting the magnification of the energy conversion abilities. The derivation of the power generated by the SSHI approach is very similar to the one performed for the standard interface. However, because of the voltage inversion, the initial conditions are changed, leading to the expression of the harvested power as a function of the driving force [16]:

(7)

for k2 QM ≥ 

3.1.2. SSHI interface The principles of the SSHI interface consists of adding in parallel with the piezoelectric element an inductor L (with an internal resistor r) in series with a digital switch S (Fig. 6(a)) [16]. The operation of the switching branch consists of connecting the piezoelement to the inductor when the displacement is either minimum or maximum. Due to the capacitive behavior of the piezoelectric element, this shapes an oscillating electrical network, and the voltage starts oscillating. In particular, if the switching time period is chosen such that the electrical oscillation lasts half a pseudo-period, this leads

1 Physically speaking, this criterion relates the available mechanical energy (through QM ), and the part of this energy that can effectively be converted in electricity (which is represented by k2 ).

(8)

2

PSSHI =

16˛2 f0 RL (1 + 2(1 − )f0 RL C0 )

×

2

2

FM 2

2Cf0 + (16f0 ˛2 RL (f0 RL C0 (1 −  2 ) + 1))/((1 + 2f0 RL C0 (1 − )) )

,

(9)

whose maximal value can be approximated as a function of k2 QM by [20]:



PSSHI 

max

≈

2 FM k2 QM . (1 − ) + 8k2 QM 8C

(10)

3.1.3. Theoretical comparison The power outputs of the standard and SSHI interfaces as a function of the resistance and of the figure of merit given by the product k2 QM of the squared coupling coefficient by the mechanical quality factor are depicted in Fig. 7, and the maximum harvested powers in Fig. 8.

Squared coupling coefficient

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

497

0.08

0.06 PZT (NAVY III type) PMN−PT 0.04

0.02 2

Fig. 7. Normalized power output as a function of the load and k2 QM ( = 0.85).

4

6

Thickness (m) These figures clearly demontrate the ability of the SSHI interface for enhancing the energy harvesting abilities for low values of k2 QM , while both the standard and SSHI techniques feature similar maximum output power for high value of the figure of merit. It can be shown from Eqs. (7) to (10) that the expression of this power limit is given by: Plim =

2 FM

8C

.

(11)

Fig. 8 shows that the SSHI get closer to this limit much quicker than the standard approach. Although such results have previously been reported [15,16,25], no particular investigation of the energy harvesting abilities of different ceramic compositions using the standard or nonlinear interfaces has been studied. 3.2. Application of the piezoceramic samples The aim of this section is to apply the previously exposed energy harvesting method to the PZT + 1 mol% Mn and PMN–25PT samples. The first step for the design of the harvesters consisted in determining the optimal sample thickness in order to maximize the coupling coefficient. This process has been done using ANSYS FE software, and results are depicted in Fig. 9. These results show that the optimal thickness of the PZT-based sample is much less than the PMN–PT (200 ␮m vs. 600 ␮m), the latter featuring a significantely higher coupling coefficient (k2 = 0.07 for the PMN–25PT while k2 = 0.045 for the PZT + 1 mol% Mn). Hence, one can expect that the PMN–PT-based harvester would be more efficient. However, due to minimal limit and uncertainties during the cutting process, the sample thickness is 0.36 mm and 0.54 mm for the PZT + 1 mol% Mn and PMN–25PT, respectively. In order to assess and compare the power generation abilities of the materials, preliminary experimental measurements have been carried out in order to determine the model parameters for

1 Standard Parallel SSHI

0.6 0.4

x 10

Fig. 9. Evolution of the global electromechanical coupling coefficient as a function of the sample thickness.

each cantilever beam. The experimental procedure is similar to the one exposed in [26], and obtained parameters are given in Table 2. The experimental set-up consists of driving the cantilever beam using an electromagnet connected to a function generator, which applies an electromagnetic force on the magnetic tip mass. An inductive proximity sensor is used in order to monitor the displacement (Fig. 3). This sensor is also connected to a DSP (dSpaceTM system) for detecting the minimum and maximum values of the displacement (such a detection can nevertheless be done in a truly self-powered fashion as it will be discussed in the next section). This system is controlling the digital switches (2N7000 MOSFETs) connected to the piezoelectric element through an inductance of 100 mH, in order to apply the nonlinear treatment. In addition to the switching interface, the harvesting stage is composed of a full diode bridge rectifier (DF005) and smoothing capacitor of 10 ␮F. This interface is connected to a resistance box, whose value can be made varying in order to determine the power generation abilities of the device with respect to the load RL . Obtained results using either the standard or SSHI approach for energy harvesting are depicted in Fig. 10. As expected, this figure clearly demonstrates that the PMN-based sample is much more effective for converting energy using the standard technique. However, a major result of this work is the ability of the SSHI to significantly decrease the power generation difference from one composition to another. As expected from the theoretical power output predictions, experimental results not only indicate that the SSHI approach allows a significant gain in terms of harvested power, but above all allows the use of less efficient (and therefore cheaper) piezoelectric materials without compromising the power generation abilities of the harvester (or equivalently permits using less amount of material). Such an effect is mainly explained by the damping effect that arise for structures featuring high values of the figure of merit k2 QM . Actually, as the nonlinear technique permits an artificial increase in

Parameter

Value PZT + 1 mol% Mn

PMN–25PT

Dynamic mass (M) Structural damping coefficient (C) Short-circuit stiffness (KE ) Force factor (˛) Blocking capacitance (C0 ) Resonance frequency (f0 ) Inversion coefficient ()

11 × 10−2 g 3.3 × 10−3 N s m−1 27.8 N m−1 3.0 × 10−5 N V−1 3.8 nF 79 Hz 0.85

9 × 10−2 g 3.5 × 10−3 N s m−1 26.2 N m−1 6.5 × 10−5 N V−1 5.4 nF 88 Hz 0.85

0.2 0 0

10 −4

Table 2 Experimental parameter identification.

P/P

lim

0.8

8

1

2

3

4

5

2

k QM Fig. 8. Normalized maximum power output as a function of k2 QM ( = 0.85).

498

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

Table 3 Energy harvesting ability comparison.

Harvested energy in standard approach Harvested energy using SSHI Global coupling coefficient Equivalent coupling coefficient using SSHI

PZT + 1 mol% Mn

PMN–25PT

PMN–25PT gain

1.7 ␮W 11.2 ␮W 9.32% 24.4%

4.5 ␮W 12.6 ␮W 17.3% 32.7%

160% 12% 86% 34%

PMN−25PT (standard) PZT + 1% Mn (standard) PMN−25PT (parallel SSHI) PZT + 1% Mn (parallel SSHI) −5

x 10

1.5

1

0.5

0

−5

Theoretical results

Power (W)

Power (W)

1.5

3

10

5

10

7

10

x 10

Experimental results

1

0.5

0

3

10

Load (Ω)

5

10

7

10

Load (Ω)

Fig. 10. Experimental harvested power using standard and SSHI approaches (FM = 0.64 mN).

the coupling coefficient (Table 3), the critical value of k2 QM (equals to  as shown in Eq. (7)) for which the power limit Plim is reached is greatly reduced. 3.3. Implementation considerations The aim of this section is to discuss about the elaboration, design and implementation of the microgenerator, both in terms of materials and electronic interface. From the material side, it has been demonstrated that the PZT + 1 mol% Mn features lower conversion abilities than the PMN–25PT. However, the elaboration of the latter is much more delicate and complex (and thus costly) because of the need of adjusting finely the quantity of MgO in order to minimize the pyroclore phase. Hence, the synthesis is usually made into three steps [27]: 1. Preparation of the mixed oxide MgNb2 O6 (columbite method) 2. Mixing with PbO + TiO2 3. Calcination

Switch

Filter

Comparator Fig. 11. Self-powered maximum detector combined with the digital switch.

In contrast, the elaboration of Mn-doped PZT powder is much easier (it only consists in mixing the reagents together) and the pure single phase PZT easier to obtain, making it simpler and cheaper to produce. In terms of electronic interfaces, the main challenge is the implementation of the digital switch. However, it has been demonstrated in the litterature that this device can be easily made self-powered using a very few amount (typically 3–5%) of the electrostatic energy available on the piezoelectric element under classical working conditions [28,29], therefore having no significant impact on the total harvested power. The principles of operations of this self-powered switching device consist of comparing the piezoelectric voltage signal with its delayed version. Then when the delayed version is lower than the original piezovoltage while being positive, a maximum value is detected (the minimum detection is done by inverting the electrodes of the circuit). Such operations can simply be done using off-the-shelf-components (resistors, capacitors and transistors), making its integration quite easy while having a very low cost (Fig. 11). From Fig. 10, it can also be shown that the optimal load when using the nonlinear interface also increases compared to the standard case. Nevertheless, it has been demonstrated that, in order to match the optimal value of the connected load, several configurations can be adopted [30,31]. In particular, the studies presented in [32] and [33] showed that using DC/DC converters operating in discontinuous mode allows the adaptation between the energy extraction interface and storage stage, therefore ensuring a maximal harvested power whatever the load connected to the system. Therefore, from these observations and from the previous analyses and experimental investigations, it can be drawn that using highly coupled electromechanical systems for energy harvesting applications is not as advantageous as it may be thought, as the power is limited due to the induced damping effect (Fig. 8). Instead, using nonlinear interfaces that allow artificially increasing the coupling coefficient of the material is a low cost, easily embeddable and efficient way for improving the energy harvesting abilities, resulting in a dramatically reduced cost while achieving similar performance than expensive materials featuring high natural coupling coefficients.

4. Conclusion This paper exposed the comparison of several energy harvesters both from the material and electronic aspects. From two different compositions of piezoelectric materials, it has been shown that the PMN–PT features higher coupling coefficient than the PZT-based sample, making such a composition a better choice for energy harvesting purposes at a first glance. Although PMN–PT-based harvester effectively allows harvesting approximately twice the power of PZT-based device when using a classical electrical interface, the use of a nonlinear approach for enhancing the conversion abilities of piezoelectric elements dramatically reduces the difference between the considered microgenerators. This is explained by the damping effect that occurs from the harvesting process when the electromechanical structure features high global coupling coefficient. Hence, it can be concluded from this paper that the design of efficient energy harvesting devices should consider both the mate-

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

rial and electronic aspects, as this latter can help in increasing the conversion abilities of piezoelements featuring moderate coupling factors. Acknowledgments The authors would like to acknowledge the support from the Franco-Thai Joint Research Project under the Partenariat Hubert Curien (PHC) Program (grant no. 20591ZL), as well as the Prince of Songkla University PhD Scholarship. References [1] J. Krikke, Sunrise for energy harvesting products, IEEE Pervasive Comput. 4 (2005) 4–35. [2] J.A. Paradiso, T. Starner, Energy scavenging for mobile and wireless electronics, IEEE Pervasive Comput. 4 (2005) 18–27. [3] D. Guyomar, Y. Jayet, L. Petit, E. Lefeuvre, T. Monnier, C. Richard, M. Lallart, Synchronized switch harvesting applied to self-powered smart systems: piezoactive microgenerators for autonomous wireless transmitters, Sens. Actuators A: Phys. 138 (1) (2007) 151–160. [4] M. Lallart, D. Guyomar, Y. Jayet, L. Petit, E. Lefeuvre, T. Monnier, P. Guy, C. Richard, Synchronized switch harvesting applied to selfpowered smart systems: piezoactive microgenerators for autonomous wireless receiver, Sens. Actuators A: Phys. 147 (1) (2008) 263–272. [5] P. Glynne-Jones, S.P. Beeby, N.M. White, Towards a piezoelectric vibrationpowered microgenerator, Sci. Meas. Technol., IEE Proc. 148 (2001) 68–72. [6] T.H. Ng, W.H. Liao, Sensitivity analysis and energy harvesting for a self-powered piezoelectric sensor, J. Intell. Mater. Syst. Struct. 16 (2005) 785–797. [7] W.Q. Liu, Z.H. Feng, J. He, R.B. Liu, Maximum mechanical energy harvesting strategy for a piezoelement, Smart Mater. Struct. 16 (2007) 2130–2136, doi:10.1088/0964-1726/16/6/015. [8] A. Badel, A. Benayad, E. Lefeuvre, L. Lebrun, D. Richard, D. Guyomar, Single crystals and nonlinear process for outstanding vibration powered electrical generators, IEEE Trans. Ultrason. Ferroelect. Freq. Contr. 53 (2006) 673–684. [9] S. Priya, D.J. Inman (Eds.), Energy Harvesting Technologies, Springer Science, New York, USA, 2005. [10] Q. Zhang, Effects of Mn doping on the ferroelectric properties of PZT thin films, J. Phys. D: Appl. Phys. 37 (2004) 98–101. [11] K.L. Yadav, P. Sharma, Synthesis and characterization of Mn doped PZT ceramics, Indian J. Eng. Mater. Sci. 15 (2008) 61–67. [12] S.E. Park, P.D. Lopath, K.K. Shung, T.R. Shrout, Relaxor-based single crystal materials for ultrasonic transducer application, Mater. Res. Innovation 1 (1997) 20–25. [13] D.-H. Suh, D.-H. Lee, N.-K. Kim, Phase developments and dielectric/ferroelectric responses in the PMN–PT system, J. Eur. Ceram. Soc. 22 (2002) 219–223. [14] J. Kelly, M. Leonard, C. Tantigate, A. Safari, Effect of composition on the electromechanical properties of (1 − x)Pb(Mg1/3 Nb2/3 )O3 xPbTiO3 ceramics, J. Am. Ceram. Soc. 80 (4) (1997) 957–964. [15] D. Guyomar, A. Badel, E. Lefeuvre, C. Richard, Towards energy harvesting using active materials and conversion improvement by nonlinear processing, IEEE Trans. Ultrason. Ferroelect. Freq. Contr. 52 (2005) 584–595. [16] E. Lefeuvre, A. Badel, C. Richard, L. Petit, D. Guyomar, A comparison between several vibration-powered piezoelectric generators for standalone systems, Sens. Actuators A 126 (2006) 405–416. [17] M. Lallart, L. Garbuio, L. Petit, D. Guyomar, Double synchronized switch harvesting (DSSH): a new energy harvesting scheme for efficient energy extraction, IEEE Trans. Ultrason. Ferroelect. Freq. Contr. 55 (10) (2008) 2119–2131. [18] M. Lallart, D. Guyomar, An optimized self-powered switching circuit for nonlinear energy harvesting with low voltage output, Smart Mater. Struct. 17 (2008), doi:10.1088/0964-1726/17/3/035030 (Paper #035030). [19] M. Lallart, L. Garbuio, C. Richard, D. Guyomar, Low-cost capacitor voltage inverter for outstanding performance in piezoelectric energy harvesting, IEEE Trans. Ultrason. Ferroelect. Freq. Contr. 57 (2) (2010) 281–291. [20] D. Guyomar, G. Sebald, S. Pruvost, M. Lallart, A. Khodayari, C. Richard, Energy harvesting from ambient vibrations and heat, J. Intell. Mater. Syst. Struct. vol.20 (2009) 609–624. [21] E. Boucher, B. Guiffard, L. Lebrun, D. Guyomar, Influence of the niobium or fluorine concentration on the properties of Mn doped lead zirconate titanate ceramics, J. Appl. Phys. 43 (2004) 5378–5538. [22] G. Sebald, L. Seveyrat, D. Guyomar, L. Lebrun, B. Guiffard, S. Pruvost, Electrocaloric and pyroelectric properties of 0.75Pb(Mg1/3 Nb2/3 )O3 − 0.25PbTiO3 single crystals, J. Appl. Phys. 100 (2006) 124112. [23] G. Sebald, A. Benayad, J. Qiu, B. Guiffard, D. Guyomar, Electromechanical characterization of 0.55Pb(Ni1/3 Nb2/3 )O3 0.45Pb(Zr0.3 Ti0.7 )O3 fibers with Pt core, J. Appl. Phys. 100 (2006) 054106. [24] A. Badel, M. Lagache, D. Guyomar, E. Lefeuvre, C. Richard, Finite element and simple lumped modeling for flexural nonlinear semi-passive damping, J. Intell. Mater. Syst. Struct. 18 (2007) 727–742. [25] Y.C. Shu, I.C. Lien, W.J. Wu, An improved analysis of the SSHI interface in piezoelectric energy harvesting, Smart Mater. Struct. 16 (2007) 2253–2264.

499

[26] A. Badel, G. Sebald, D. Guyomar, M. Lallart, E. Lefeuvre, C. Richard, J. Qiu, Piezoelectric vibration control by synchronized switching on adaptive voltage sources: towards wideband semi-active damping, J. Acoust. Soc. Am. 119 (5) (2006) 2815–2825, doi:10.1121/1.2184149. [27] H. Yamada, Pressureless sintering of PMN-PT ceramics, J. Eur. Ceram. Soc. 19 (1999) 1053–1056. [28] C. Richard, D. Guyomar, E. Lefeuvre, Self-powered electronic breaker with automatic switching by detecting maxima or minima of potential difference between its power electrodes, patent # PCT/FR2005/003000, publication number: WO/2007/063194 (2007). [29] M. Lallart, E. Lefeuvre, C. Richard, D. Guyomar, Self-powered circuit for broadband, multimodal piezoelectric vibration control, Sens. Actuators A: Phys. 143 (2) (2008) 277–382. [30] G.K. Ottman, H.F. Hofmann, A.C. Bhatt, G.A. Lesieutre, Adaptive piezoelectric energy harvesting circuit for wireless remote power supply, IEEE Trans. Power Electron. 17 (5) (2002) 669–676. [31] J. Han, A. Von-Jouanne, T. Le, K. Mayaram, T.S. Fiez, Novel power conditioning circuits for piezoelectric micro power generators, Proc. IEEE Appl. Power Electron. Conf. Expo. (APEC) 3 (2004) 1541–1546. [32] G.K. Ottman, H.F. Hofmann, G.A. Lesieutre, Optimized piezoelectric energy harvesting circuit using step-down converter in discontinuous conduction mode, IEEE Trans. Power Electron. 18 (2) (2003) 696–703. [33] E. Lefeuvre, D. Audigier, C. Richard, D. Guyomar, Buck-boost converter for sensorless power optimization of piezoelectric energy harvester, IEEE Trans. Power Electron. 22 (5) (2007) 2018–2025.

Biographies Prissana Rakbamrung received her B.Sc and M.Sc in 2003 and 2007 respectively, both from Prince of Songkla University. She is now studying toward her Ph.D degree at the Material Physics Laboratory, Prince of Songkla University and has joined the Laboratoire de Génie Electrique et Ferroélectricité (LGEF), Institut National des Sciences Appliquées de Lyon (INSA), Lyon, France, from September to December 2009. Her research involves piezoceramics and ferroelectric polymers. This includes the evaluation of their performance in energy harvesting applications. Mickaël Lallart graduated from Institut National des Sciences Appliquées de Lyon (INSA Lyon), Lyon, France, in electrical engineering in 2006, and received his Ph.D in electronics, electrotechnics, and automatics from the same university in 2008, where he worked for the Laboratoire de Génie Électrique et Ferroélectricité (LGEF). After working as a post-doctoral fellow in the Center for Intelligent Material Systems and Structures (CIMSS) in Virginia Tech, Blacksburg, VA, USA in 2009, Dr. Lallart has been hired as an Associate Professor in the Laboratoire de Génie Électrique et Ferroélectricité. His current field of interest focuses on vibration damping, energy harvesting and Structural Health Monitoring using piezoelectric, pyroelectric or electrostrictive devices, as well as autonomous, self-powered wireless systems. Daniel Guyomar received a master degree in mechanical engineering, a Ph.D in Acoustic and vibrations from Compiègne University (France) and a Ph.D in Physics from Paris VII University (France). In 1982–1983, he worked as a Research Associate in fluid dynamics at University of Southern California (USC) Los Angeles. From 1983 to 1984, he was a National Research Council Awardee at the Monterey Naval Postgraduate School (CA) to develop transient wave radiation modeling. In 1985, he was hired by the Schlumberger group to lead several projects dealing with ultrasonic imaging and then move to Thomson Submarine Activities in 1987 to manage the research activities in the field of physical underwater acoustics. He co-created two start-ups involved in ultrasonic devices. He is presently a full time Professor at Institut National des Sciences Appliquées de Lyon (France) where he manages the Electrical Engineering and Ferroelectricity Laboratory (Laboratoire de Génie Électrique et Ferroélectricité - LGEF). His present research interests are in the field of smart materials and systems: semi-active vibration control, wave control, energy harvesting, piezo-transformers, electroactive materials and nonlinear/hysteretic modeling of these materials. Nantakan Muensit received her B.Sc from Prince of Songkla University in 1983 and M.Sc from Chulalongkorn University in 1986. In 1999, she obtained a Ph.D of Material Physics from Macquarie University, Sydney, Australia. She has been a faculty member at Prince of Songkla University since 1987 and became an Associate Professor in 2004. Her research interests are the fundamentals and applications of ferroelectric materials in bulk and film forms. Her publications include books and over 100 papers in various refereed journals and conference proceedings. Chanchana Thanachayanont received her B.Eng from Department of Materials Science and Engineering, Imperial College, London in 1994 and Ph.D from the same department in 1999. She has worked as a researcher at the National Metal and Materials Technology Center since 1999 and now is a head of the Transmission Electron Microscopy Laboratory. Her research interests focus on energy harvesting devices such as dye sensitized solar cells and thermoelectric devices. Claude Lucat received his Ph.D in inorganic Chemistry from Bordeaux University in 1980. He joined the Centre National de la Recherche Scientifique (CNRS) in 1979. Currently, he is Director of Research at the Laboratoire de l’Intégration du Matériau au Système (IMS), University of Bordeaux, France. He is interested in the application and development of screen-printed thick-film materials devoted to components and microsystems. His current researches focus on piezo-cantilevers and self-supporting

500

P. Rakbamrung et al. / Sensors and Actuators A 163 (2010) 493–500

ceramics or polymer-based devices for gas sensing, force sensors, energy harvesting and other applications involving electroactive transducers. Benoît Guiffard graduated from the Ecole Nationale Supérieure (ENS) de Chimie de Rennes, France in 1995. He joined the Laboratoire de Génie Electrique et Ferroélectricité (LGEF) at the Institut National des Sciences Appliquées (INSA), Lyon, France in 1996, where he obtained his Ph.D in Inorganic Chemistry in 1999. He became Associate Professor at INSA in 2000 where he started to work on the doping of piezoelectric materials (ceramics, single crystals). His present research interests include the development of electroactive polymer composites exhibiting multiferroic behavior for enhanced sensing capability and external field-induced strain. In this topic, he is currently involved in the optimization of actuation performances of nano-objects filled semi-crystalline elastomers and investigation of magneto-electric composite films loaded with magnetic nanoparticles.

Lionel Petit received the M.Sc degree in 1992 from the University of Claude Bernard, Lyon, France and the Ph.D in acoustics in 1996 from the Institut National des Sciences Appliquées (INSA), Lyon for his work on piezoelectric motors. He joined the Laboratoire de Génie Electrique et Ferroélectricité (LGEF) where he has been an Associate Professor from 1998 to 2009. He received the diploma of “Habilitation à Diriger des Recherches” in 2006 for his work on multiphysic coupling applied to vibration control and energy harvesting, and got a full time Professor position in 2009. His current research interests include the development and characterization of electroactive smart materials, energy harvesting and smart self-powered systems. Pisan Sukwisut received B.Sc and M.Sc degrees in Physics from Prince of Songkla University in 2007 and 2009, respectively. He then continues studying in the Ph.D Program at the Material Physics Laboratory, Physics Department, Prince of Songkla University under the RGJ scholarship, Ministry of Science and Technology, Bangkok. His work involves energy conversion in electrostrictive materials.