The potential application of this energy harvesting has been recognized in the form of the replacement of batteries of the pacemakers. Since the Ni-Cd or Li-ion batteries used for pacemakers have finite life span [15] and hence these require replacement after a certain period. To overcome this drawback, researchers have been exploring methods where an energy harvester could scavenge energy from human body and power the pacemaker.Goto et al. [16] carried out the pioneering work in the field of powering leadless pacemakers. A kinetic watch energy generating system was employed on a dog's heart and 13 µJ of energy per heartbeat was successfully achieved. Tashiro et al. conducted an experiment where pacemaker was powered by harvesting enough energy from the motion of canine heart. [17] However, the design proposed by them is practically impossible to be placed inside the thoracic cavity of the laboratory animal. Recently, Karami and Inman [12] have proposed zig-zag structures to achieve lower frequencies with piezoceramics to power pacemaker implanted in chest. Heart beat acceleration was used in this study for actuating the harvester but the size of harvester is too large to be inserted into intravenous cavity. Zurbuchen et al. recently conducted an in vivo study on pig's heart for 30 min. [18] Their study aimed at demonstration of battery and leadless cardiac pacing by using energy harvesting mechanism derived from Swiss wristwatch. It was shown that the mechanism generated sufficient electrical power (<10 µW) to meet out the demand of a typical modern pacemaker. [19] A number of researchers have carried out research in this field where piezoelectric energy harvester has been employed to power pacemaker. An exhaustive literature review regarding piezoelectric energy harvesting for pacemaker application along with limitations has been presented in Table 1.The size of miniaturized leadless pacemaker should be such that it can be directly placed inside the heart. [25] So, the size of the pacemaker should be compatible with intravenous introduction, that is, its diameter should be around 6 mm. However, most of the designs proposed so far [20][21][22]12] have dimensions more than that of intravenous cavity hence very impractical from pacemaker design point of view. To the best of authors' knowledge, there is hardly any literature available dealing with the design and study of the energy harvesting systems
In this article, we focus on cement-binded Ba0.85Sr0.15Zr0.1Ti0.9O3 ceramics for pyroelectric applications. It was prepared with the Ba0.85Sr0.15Zr0.1Ti0.9O3-to-cement ratios of 85%:15% and 80%:20% by weight. In order to improve the effectiveness of thermal-to-electric energy conversion, the synchronized switch harvesting on inductor technique is experimentally tested on cement composites. Our experimental findings reveal that this concept based on synchronized switch harvesting on inductor can significantly increase the amount of power extracted from pyroelectric materials. Furthermore, the optimized power across 15% and 20% cement composites were found to be 7.2 and 6 nW, respectively, in series synchronized switch harvesting on inductor and 8.5 and 7 nW, respectively, in parallel synchronized switch harvesting on inductor. These values are significantly higher when compared with non-switched circuit for pyroelectric applications. Although, from the obtained results for the prepared composites, the power output is less when compared with pure Ba0.85Sr0.15Zr0.1Ti0.9O3, they have some advantages: these composites can be made without any sintering process and are compatible for structural applications.
The thermal energy harvesting potential of different pyroelectric materials including Sr0.5Ba0.5Nb2O5 (SBN), [Bi0.48Na0.4032K0.0768] Sr0.04(Ti0.975Nb0.025)O3 (BNT‐Nb), Ba0.85Sr0.15Zr0.1Ti0.9O3 (BST‐BZT), Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCT‐BZT), and Ba0.9Ca0.1TiO3 (BCT) ceramics is compared. Amongst these materials, BCT is found to be best for pyroelectric energy harvesting. Open‐circuit voltages were found to be 1.7 V, 500 mV, 650 mV, 600 mV, and 400 mV for BCT, SBN, BCT‐BZT, BST‐BZT, and BNT‐Nb, respectively. BCT is further analyzed, revealing an optimum power output of 0.072 μW at the optimized cycle frequency (0.06 Hz) and at a load resistance of 18 MΩ. To improve the effectiveness of energy conversion from heat to electricity, the synchronized switch harvesting on inductor (SSHI) technique is experimentally tested on a BCT sample. It is revealed that this concept based on SSHI can significantly increase the amount of power extracted from pyroelectric materials. Compared with 0.072 μW across a standard circuit in a BCT sample, an enhanced power output of 0.16 μW and 0.14 μW is obtained using parallel and series SSHI, respectively at 0.06 Hz. The results reveal that the non‐linear processing technique based on SSHI leads to significant power improvement compared to non‐switched interface.
Conventional pacemaker batteries have limited lifetime and require a major surgery for replacement. To overcome this impediment, a design for piezoelectric energy harvester scavenging energy from blood pressure variation in the patient's body is proposed. This piezoelectric energy harvester converts the force arising from blood pressure variation into electric voltage. The image shows the self‐powered pacemaker; the background portrays the campus of the Indian Institute of Technology Mandi, India, where the research was carried out. Further details can be found in article number 1700084 by Rahul Vaish and co‐workers.
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