Power and frequency bandwidth improvement of piezoelectric energy harvesting devices using phase-shifted synchronous electric charge extraction interface circuit

Lefeuvre, Elie,Badel, Adrien,Brenes, Alexis,Seok, Seonho,Yoo, Chan-Sei Sage Science Press (UK) 2017 Journal of intelligent material systems and struct Vol. No.

Analysis of piezoelectric energy harvesting system with tunable SECE interface

Lefeuvre, E,Badel, A,Brenes, A,Seok, S,Woytasik, M,Yoo, C-S Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.3

<P>Numerous interface circuits have been proposed over the past years to improve the performances of piezoelectric energy harvesting devices. The so-called synchronous electric charge extraction interface (SECE) brought the advantage of harvesting power independently of the load voltage. In counterpart, its performances exhibited sensitivity to the electromechanical coupling. It was shown, in particular, that harvested power was significantly decreased at high coupling. To overcome this drawback, the so-called tunable SECE interface has recently been proposed. Instead of the total charge extraction performed by the original SECE, the tuning method consists in extracting only a portion of the electric charge. This paper presents the analytical modeling of an energy harvesting system composed of a linear piezoelectric resonator associated to the tunable SECE interface. Contrary to previous model limited to describe the system behavior at resonance, this model enables to extend the analysis off-resonance. The presented theoretical analysis and experimental results clearly show the possibility to increase both the power and the frequency bandwidth by adequate control of the tunable SECE interface.</P>

Shunt-diode rectifier: a new scheme for efficient piezoelectric energy harvesting

Brenes, Alexis,Lefeuvre, Elie,Badel, Adrien,Seok, Seonho,Yoo, Chan-Sei Institute of Physics Publishing 2019 Smart materials & structures Vol.28 No.1

<P>This paper highlights the interest of shunt-diode rectifiers to optimize the performances of piezoelectric vibration energy harvesters based on linear load adaptation. It provides, for the first time, a full analytical study of the input power and frequency bandwidth of such a system. We show that this architecture is well-suited for piezoelectric energy harvesting. In the presented approach, a so-called shunt diode is connected across the electrodes of the piezoelectric transducer, which makes the piezoelectric voltage unidirectional instead of alternating. Thus, DC–DC converters usually used for power optimization can be directly connected to the transducer. We show that weakly-coupled linear inertial piezoelectric energy harvesters generate higher power when connected to a shunt-diode rectifier than to a bridge rectifier. Moreover, the frequency bandwidth is enlarged by the use of the single-diode shunt rectifier, especially for strongly-coupled piezoelectric generators. The proposed architecture is also interesting for low piezoelectric voltages, at which voltage drops across the diodes used for AC–DC conversion critically degrade the power efficiency. Experimental results validate the presented analytical study and highlight the higher efficiency of the shunt-diode rectifier circuit. Compared to a standard bridge rectifier architecture, we demonstrate an increase of +43% output power on a weakly-coupled generator and an increase of +5% bandwidth on a strongly-coupled generator.</P>

Unipolar synchronized electric charge extraction for piezoelectric energy harvesting

Brenes, Alexis,Lefeuvre, Elie,Badel, Adrien,Seok, Seonho,Yoo, Chan-Sei Institute of Physics Publishing 2018 Smart materials & structures Vol.27 No.7

<P>This paper highlights the interest of a shunt rectifier to improve the efficiency of the synchronized electric charge extraction (SECE) circuit formerly developed for piezoelectric energy harvesters. Compared to the classical SECE circuit, which requires a full-bridge rectifier, the proposed architecture is especially interesting for low-amplitude vibrations generating a low piezoelectric voltage, typically lower than 2 V RMS. We provide a full analytical study validated by experimental measurements to illustrate the high performance of the so-called unipolar SECE (USECE) as well as the impact of the resonator characteristics on the overall performance of the harvester. We also propose a model including the main causes of power dissipation, which is validated experimentally, showing that the power efficiency of the circuit is much less dependent on the vibration frequency and magnitude than classical SECE. The proposed architecture combines the high input power of SECE with the high power efficiency resulting from unipolar operation, reaching more than 75% power efficiency in situations where classical SECE is limited to an efficiency lower than 35%. Our experimental results show an increase of +200% output power obtained with USECE compared to classical SECE, which is due to the combination of a higher input power and a higher power efficiency of the proposed circuit.</P>

New hybrid agarose/Cu-Bioglass® biomaterials for antibacterial coatings

Eric Wers,Bertrand Lefeuvre 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

Agarose hydrogels, combined with 45S5 Bioglass®, were elaborated to serve as copper delivery systems. Our aim was to study the antibacterial properties of these hydrogels. The results show that the amount of glass does not influence the stiffness properties, but it improves the hydrophilicity and the swelling profile of agarose hydrogel. Two bacterial strains, Bacillus sp. 4J6 and Pseudomonas aeruginosa sp. PAO1, were chosen. Their retention on the substrates was analyzed by confocal laser scanning microscopy. The mechanical characteristics and the release of copper have an effect on the bacterial adhesion and the biofilm formation. All the obtained results indicate that these hydrogels could be adapted to a potential application to the antibacterial coatings.

Fermented Soy Permeate Reduces Cytokine Level and Oxidative Stress in Streptozotocin-Induced Diabetic Rats

Ludivine Malarde,Carole Groussard,Luz Lefeuvre-Orfila,Sophie Vincent,The´o Efstathiou,Arlette Gratas-Delamarche 한국식품영양과학회 2015 Journal of medicinal food Vol.18 No.1

Oxidative stress and inflammation are involved in the development of type 1 diabetes and its complications. Because two compounds found in soy, that is, isoflavones and alpha-galactooligosaccharides, have been shown to exert antioxidant and anti-inflammatory effects, this study aimed to assess the effects of a dietary supplement containing these two active compounds, the fermented soy permeate (FSP). We hypothesized that FSP would be able to reduce in vivo oxidative stress and inflammation in streptozotocin (STZ)–induced type 1 diabetic rats. Thirty male Wistar rats were divided into the control placebo, diabetic placebo, and diabetic FSP-supplemented groups. They received daily, by oral gavage, water (placebo groups) or diluted FSP (0.1 g/day; FSP-supplemented group). After 3 weeks, glycemic regulation (glycemia and fructosamine level); the plasma level of carboxymethyllysine (CML), a marker of systemic oxidative stress in diabetes; and the plasma levels of inflammatory markers (CRP, IL-1β, IL-6, and uric acid) were evaluated. Markers of oxidative damage (isoprostanes and GSH/GSSG), antioxidant enzymatic activity (SOD and GPX), and Mn-SOD content were determined in skeletal muscle (gastrocnemius). Diabetic placebo rats exhibited higher CML levels, lower SOD and GPX activities, and decreased Mn-SOD contents. FSP supplementation in diabetic animals normalized the CML and antioxidant enzymatic activity levels and tended to increase Mn-SOD expression. The markers of inflammation whose levels were increased in the diabetic placebo group were markedly decreased by FSP (IL-1β: - 75%, IL-6: - 46%, and uric acid: - 17%), except for CRP. Our results demonstrate that FSP exhibited antioxidant and anti-inflammatory properties in vivo in STZ-induced diabetic rats.

A Fermented Soy Permeate Improves the Skeletal Muscle Glucose Level Without Restoring the Glycogen Content in Streptozotocin-Induced Diabetic Rats

Ludivine Malarde,Sophie Vincent,Luz Lefeuvre-Orfila,The´o Efstathiou,Carole Groussard,Arlette Gratas-Delamarche 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.2

Exercise is essential into the therapeutic management of diabetic patients, but their level of exercise tolerance is lowered due to alterations of glucose metabolism. As soy isoflavones have been shown to improve glucose metabolism, this study aimed to assess the effects of a dietary supplement containing soy isoflavones and alpha-galactooligosaccharides on muscular glucose, glycogen synthase (GSase), and glycogen content in a type 1 diabetic animal model. The dietary supplement tested was a patented compound, Fermented Soy Permeate (FSP), developed by the French Company Sojasun Technologies. Forty male Wistar rats were randomly assigned to control or diabetic groups (streptozotocin, 45 mg/kg). Each group was then divided into placebo or FSP-supplemented groups. Both groups received by oral gavage, respectively, water or diluted FSP (0.1 g/day), daily for a period of 3 weeks. At the end of the protocol, glycemia was noticed after a 24-h fasting period. Glucose, total GSase, and the glycogen content were determined in the skeletal muscle (gastrocnemius). Diabetic animals showed a higher blood glucose concentration, but a lower glucose and glycogen muscle content than controls. Three weeks of FSP consumption allowed to restore the muscle glucose concentration, but failed to reduce glycemia and to normalize the glycogen content in diabetic rats. Furthermore, the glycogen content was increased in FSP-supplemented controls compared to placebo controls. Our results demonstrated that diabetic rats exhibited a depleted muscle glycogen content (−25%). FSP-supplementation normalized the muscle glucose level without restoring the glycogen content in diabetic rats. However, it succeeded to increase it in the control group (+20%).

Antibacterial and in vivo reactivity of bioactive glass and poly(vinyl alcohol) composites prepared by melting and sol-gel techniques

Salha Boulila,Hafed Elfeki,Hassane Oudadesse,Rim Kallel,Bertrand Lefeuvre,Mostafa Mabrouk,Slim Tounsi,Dhekra Mhalla,Amany Mostafa,Khansa Chaabouni,Fatma Makni-Ayedi,Allal Barroug,Tahia Boudawara,Abdel 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5

Bioactive glass particle is used in the repair of bone defects. This material undergoes a series of surface in vivo reactions, which leads to osteointegration. We evaluated the effect of the bioactive glass synthesis, sol-gel (BG(S)) versus melting (BG(M)), associated with polyvinyl-alcohol (PVA) on in vivo bioactivity with biochemical parameters, liver-kidney histological structure and antibacterial in vitro activity. These composites were testified in many bacteria and implanted in ovariectomized rat. The serum and organs (liver and kidney) of all groups, control and treated rats, were collected to investigate the side effects of our composites, BG(S)-PVA and BG(M)-PVA, in comparison with control and ovariectomized rats. Also, the implants, before and after implantation, were prepared for analysis using physicochemical techniques such as Fourier transform infrared spectroscopy and X-ray diffraction. Our results have shown the stability of natremia, kaliemia, calcemia and phosphoremia. The histological structures of liver and kidney in implanted rats are intact compared to control and ovariectomized rats. BG(S)-PVA is characterized by a higher antibacterial effect on negative and positive gram bacteria than BG(M)-PVA. The physicochemical results have confirmed a progressive degradation of BG(S)-PVA and BG(M)-PVA, while replacing the implant by an apatite layer. But this bioactivity of BG(S)-PVA is faster than BG(M)-PVA. We can therefore confirm, on the one hand, the biocompatibility of our two implants and, on the other hand, the beneficial effect of sol-gel synthesis technique versus melting, both on the antibacterial effect and on the rapid formation of layer hydroxyapatite, and consequently on osteogenesis.