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1. On-Body Piezoelectric Energy Harvesters through Innovative Designs and Conformable Structures

   https://doi.org/10.1021/acsbiomaterials.1c00800  

   Fernandez, Sara V. ; Cai, Fiona ; Chen, Sophia ; Suh, Emma ; Tiepelt, Jan ; McIntosh, Rachel ; Marcus, Colin ; Acosta, Daniel ; Mejorado, David ; Dagdeviren, Canan ( October 2021 , ACS Biomaterials Science & Engineering)

   Recent advancements in wearable technology have improved lifestyle and medical practices, enabling personalized care ranging from fitness tracking, to real-time health monitoring, to predictive sensing. Wearable devices serve as an interface between humans and technology; however, this integration is far from seamless. These devices face various limitations such as size, biocompatibility, and battery constraints wherein batteries are bulky, are expensive, and require regular replacement. On-body energy harvesting presents a promising alternative to battery power by utilizing the human body’s continuous generation of energy. This review paper begins with an investigation of contemporary energy harvesting methods, with a deep focus onmore »piezoelectricity. We then highlight the materials, configurations, and structures of such methods for self-powered devices. Here, we propose a novel combination of thin-film composites, kirigami patterns, and auxetic structures to lay the groundwork for an integrated piezoelectric system to monitor and sense. This approach has the potential to maximize energy output by amplifying the piezoelectric effect and manipulating the strain distribution. As a departure from bulky, rigid device design, we explore compositions and microfabrication processes for conformable energy harvesters. We conclude by discussing the limitations of these harvesters and future directions that expand upon current applications for wearable technology. Further exploration of materials, configurations, and structures introduce interdisciplinary applications for such integrated systems. Considering these factors can revolutionize the production and consumption of energy as wearable technology becomes increasingly prevalent in everyday life.« less
2. OPTIMIZATION OF A RAINBOW PIEZOELECTRIC ENERGY HARVESTING SYSTEM FOR TIRE MONITORING APPLICATIONS Proceedings of the ASME 2018 12th International Conference on Energy Sustainability ES2018 June 24-28, 2018, Lake Buena Vista, FL, USA ES2018-7496

   Roja Esmaeeli, Haniph Aliniagerdroudbari ( June 2018 , Proceedings of the ASME 2018 12th International Conference on Energy Sustainability ES2018 June 24-28, 2018, Lake Buena Vista, FL, USA)

   Ambient energy harvesting using piezoelectric transducers is becoming popular to provide power for small microelectronics devices. The deflection of tires during rotation is an example of the source of energy for electric power generation. This generated power can be used to feed tire selfpowering sensors for bicycles, cars, trucks, and airplanes. The aim of this study is to optimize the energy efficiency of a rainbow shape piezoelectric transducer mounted on the inner layer of a pneumatic tire for providing enough power for microelectronics devices required to monitor tires. For this aim a rainbow shape piezoelectric transducer is adjusted with themore »tire dimensions and excited based on the car speed and strain. The geometry and load resistance effects of the piezoelectric transducer is optimized using Multiphysics modeling and finite« less
3. Design of a Reverse-Electrowetting Transducer Based Wireless Self-powered Motion Sensor

   https://doi.org/10.1109/ISCAS45731.2020.9180973  

   Tasneem, Nishat T. ; Biswas, Dipon K. ; Adhikari, Pashupati R. ; Reid, Russell ; Mahbub, Ifana ( October 2020 , IEEE International Symposium on Circuits and Systems proceedings)

   This paper presents a self-powered motion sensor based on reverse-electrowetting on dielectric (REWOD) energy harvesting having the capability of remotely keeping a track of any motion activity. The energy harvester includes a rectifier and a voltage regulator to provide the DC supply voltage to the analog front-end and the transmitter to wirelessly transfer the data from the motion sensor. The on-chip circuitry includes a seven-stage voltage-doubler based rectifier, an amplifier, an analog-to-digital converter (ADC), and a transmitter, and is designed in standard 180 nm CMOS process with a supply voltage of 1.8 V. The recycled folded cascode (RFC) based chargemore »amplifier has a closed-loop gain of 53 dB within the bandwidth of 1-150 Hz, which is suitable to detect any low-frequency motion signal. An 8-bit SAR-ADC is designed to digitize the amplified signal with a sampling rate of 1 ksamples/s. The transmitter used for this application operates in the 3.1-5 GHz frequency band with an energy efficiency of 8.5 pJ/pulse at 100 kbps data rate. The wireless motion sensing device with the REWOD can be suitable for quantitatively monitoring the motion-related data as a wearable sensor.« less
4. Energy Harvesting Floor from Commercial Cellulosic Materials for a Self-Powered Wireless Transmission Sensor System

   Gu, Long ; German, Lazarus ; Li, Tong ; Li, Jun ; Shao, Yan ; Long, Yin ; Wang, Jingyu ; Wang, Xudong ( January 2021 , ACS applied materials interfaces)

   Cellulose-based materials have gained increasing attention for the development of low cost, eco-friendly technologies, and more recently, as functional materials in triboelectric nanogenerators (TENGs). However, the low output performance of cellulose-based TENGs severely restricts their versatility and employment in emerging smart building and smart city applications. Here, we report a high output performance of a commercial cellulosic material-based energy harvesting floor (CEHF). Benefiting from the significant difference in the triboelectric properties between weighing and nitrocellulose papers, high surface roughness achieved by a newly developed mechanical exfoliation method, and large overall contact area via a multilayered device structure, the CEHF (25more »cm × 15 cm × 1.2 cm) exhibits excellent output performance with a maximum output voltage, current, and power peak values of 360 V, 250 μA, and 5 mW, respectively. It can be directly installed or integrated with regular flooring products to effectively convert human body movements into electricity and shows good durability and stability. Moreover, a wireless transmission sensing system that can produce a 1:1 footstep-to-signal (transmitted and received) ratio is instantaneously powered by a TENG based entirely on cellulosic materials for the first time. This work provides a feasible and effective way to utilize commercial cellulosic materials to construct self-powered wireless transmission systems for real-time sensing applications.« less
5. Smart Tooth System for In-Situ Wireless PH Monitoring

   https://doi.org/10.1109/Transducers50396.2021.9495706  

   Islam, Sayemul ; Kim, Albert ; Hwang, Geelsu ; Song, Seung Hyun ( August 2021 , 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers))

   In this paper, we introduce an oral motion-powered Smart Tooth system that can monitor oral health. Lower pH is an indicator of bacterial accumulation in the oral cavity, which can cause tooth decay, periodontal or peri-implant diseases. Thus, in situ monitoring pH inside of the mouth is critical to prevent oral diseases. Using a piezoelectric dental crown, Smart Tooth system converts oral motions, such as chewing, to electrical power which can impinge a surface integrated LC transponder. The LC transponder also incorporates iron oxide nanoparticles-embedded pH-sensitive hydrogel that modulates the resonant frequency via shrinking or swelling. As a proof ofmore »concept, the fabricated prototype measures pH levels ranging from pH 4 to 12 and sends data wirelessly to the receiver placed up to 5 cm away (wireless transmission path loss at 3 cm was 50.79 dB). The results indicate that the Smart Tooth system can monitor oral health while replacing missing teeth.« less