Wearable devices rely on hybrid mechanisms that possess the advantages of establishing a smarter system for healthcare, sports monitoring, and smart home applications. Socks with sensing capabilities can reveal more direct sensory information on the body for longer duration in daily life. However, the limitation of suitable materials for smart textile makes the development of multifunctional socks a major challenge. In this paper, we have developed a self-powered and self-functional sock (S2-sock) to realize diversified functions including energy harvesting and sensing various physiological signals, i.e., gait, contact force, sweat level, etc., by hybrid integrating poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS)-coated fabric triboelectric nanogenerator (TENG) and lead zirconate titanate (PZT) piezoelectric chips. An output power of 1.71 mW is collected from a PEDOT:PSS-coated sock with mild jumping at 2 Hz and load resistance of 59.7 MΩ. The study shows that cotton socks worn daily can potentially be a power source for enabling self-sustained socks comprising wireless transmission modules and integrated circuits in the future. We also investigate the influences of environmental humidity, temperature, and weight variations and verify that our S2-sock can successfully achieve walking pattern recognition and motion tracking for smart home applications. On the basis of the sensor fusion concept, the outputs from TENG and PZT sensors under exercise activities are effectively merged together for quick detection of the sweat level. By leveraging the hybrid S2-sock, we can achieve more functionality in the applications of foot-based energy harvesting and monitoring the diversified physiological signals for healthcare, smart homes, etc.
Implantable medical devices are widely used for monitoring and treatment of severe diseases. In particular, an implantable cardiac pacemaker is the most effective therapeutic device for treating bradyrhythmia, however its surgical replacement is inevitable every 5–12 years due to the limited life of the built-in battery. Although several approaches of energy harvesting have been explored in this decade for powering cardiac pacemakers, the modern, commercial, and full-function pacemaker has never been powered effectively yet. Here, we report an integrated strategy for directly powering a modern and full-function cardiac pacemaker, which can pace the porcine heart in vivo by harvesting the natural energy of a heartbeat, without using any external energy storage element. The generator includes an elastic skeleton and two piezoelectric composites, which could generate a high-output current of 15 μA in vivo over state-of-the-art performance. This study makes an impressive step toward fabricating a self-powered cardiac pacemaker and resolving the power issue of implantable medical devices by piezoelectric harvesting technology.
Piezoelectric arterial pulse wave dynamics are traditionally considered to be similar to those of typical blood pressure waves. However, achieving accurate continuous blood pressure wave monitoring based on arterial pulse waves remains challenging, because the correlation between piezoelectric pulse waves and their related blood pressure waves is unclear. To address this, the correlation between piezoelectric pulse waves and blood pressure waves is first elucidated via theoretical, simulation, and experimental analysis of these dynamics. Based on this correlation, the authors develop a wireless wearable continuous blood pressure monitoring system, with better portability than conventional systems that are based on the pulse wave velocity between multiple sensors. They explore the feasibility of achieving wearable continuous blood pressure monitoring without motion artifacts, using a single piezoelectric sensor. These findings eliminate the controversy over the arterial pulse wave piezoelectric response, and can potentially be used to develop a portable wearable continuous blood pressure monitoring device for the early prevention and daily control of hypertension.
Triboelectric nanogenerators (TENGs) converting mechanical energy into electrical energy have received much attention because of their huge potential applications for supplying power to electronic devices. Improving the performance of TENGs has become a research hot point because of their output limited current. In this paper, we propose a flexible single-electrode triboelectric nanogenerator based on porous NaCO/polydimethylsiloxane (PDMS) structure to enhance the triboelectric performance for nanogenerators. To compare their output performance, NaCl and sugar are normally used as sacrificial template for triboelectric nanogenerator. As an experimental result, the nanogenerator based on porous NaCO/PDMS structure obtains the open-circuit voltage of 125 V and maximum output current of 100 μA, which are higher than that generated by NaCl/PDMS and sugar/PDMS TENGs. And the generated electric energy of NaCO/PDMS TENG could instantaneously power 42 commercial light-emitting diodes without any energy storage devices. This developed porous NaCO/PDMS TENG could open a new application field for self-powered personal electronics because of its flexibility, simple manufacturing process, and the ability to harvest mechanical energy from human motions.
Purpose This work aims to evaluate the influence of rheological properties of building materials on the bonding quality and ultimate tensile strength in the fused deposition modeling (FDM) process, through the investigation of parts printed by semi-crystalline and amorphous resins. Little information is currently available about the influence of the crystalline nature on FDM-printed part quality. Design/methodology/approach Semi-crystalline polyamide 12 and amorphous acrylonitrile butadiene styrene (ABS) were used to assess the influence of rheological properties on bonding quality and the tensile strength, by varying three important process parameters: materials, liquefier temperature and raster orientation. A fractography of both tensile and freeze-fractured samples was also investigated. Findings The rheological properties, mainly the melt viscosity, were found to have a significant influence on the bonding quality of fused filaments. Better bonding quality and higher tensile strength of FDM parts printed with semi-crystalline PA12, as compared with amorphous ABS, are suggested to be a result of higher initial sintering rates owing to the lower melt viscosity of PA12 at low shear rates. Near-full dense PA12 parts were obtained by FDM. Originality/value This project provides a variety of data and insight regarding the effect of materials properties on the mechanical performance of FDM-printed parts. The results showed that FDM technique allows the production of PA12 parts with adequate mechanical performance, overcoming the greatest limitation of a dependence on amorphous thermoplastics as a feedstock for the production of prototypes.
Micro- and nanopatterning of cost-effective addressable metallic nanostructures has been a long endeavor in terms of both scientific understanding and industrial needs. Herein, a simple and efficient dynamic meniscus-confined electrodeposition (MCED) technique for precisely positioned copper line micropatterns with superior electrical conductivity (greater than 1.57 × 10 S/cm) on glass, silicon, and gold substrates is reported. An unexpected higher printing speed in the evaporative regime is realized for precisely positioned copper lines patterns with uniform width and height under horizontal scanning-mode. The final line height and width depend on the typical behavior of traditional flow coating process, while the surface morphologies and roughness are mainly governed by evaporation-driven electrocrystallization dynamics near the receding moving contact line. Integrated 3D structures and a rapid prototyping of 3D hot-wire anemometer are further demonstrated, which is very important for the freedom integration applications in advanced conceptual devices, such as miniaturized electronics and biomedical sensors and actuators.
Over the past half‐century, cardiac pacing technology has adhered to one basic system. However, many pacemaker‐related complications are related to this system, particularly in terms of the power supply and leads. Here, for the first time a heart‐worn pacemaker strategy is presented, which allows batteryless powering and leadless pacing. The batteryless feature is attained via heart‐extrusion energy scavenging through a micromachined piezoelectric thick film transducer. A record in vivo output current of 30 µA is obtained in an adult swine by the implanted piezoelectric transducer, which can effectively drive a commercial cardiac pacemaker. The exocardial pacing method is demonstrated by this batteryless pacemaker functions without a device or leads placed within the cardiac chambers. Lead‐ or batteryless options are being explored as new basic features of cardiac pacemakers. The presented heart‐worn pacemaker strategy may be useful in future pacing technology.
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