As rapid development in wearable/implantable electronic devices benefit human life in daily health monitoring and disease treatment medically, all kinds of flexible and/or stretchable electronic devices are booming, together with which is the demanding of energy supply with similar mechanical property. Due to its ability in converting mechanical energy lying in human body into electric energy, energy harvesters based on piezoelectric materials are promising for applications in wearable/implantable device's energy supply in a renewable, clean and life-long way. Here the mechanics of traditional piezoelectrics in energy harvesting is reviewed, including why piezoelectricity is the choice for minor energy harvesting to power the implantable/wearable electronics and how. Different kinds of up to date flexible piezoelectric devices for energy harvesting are introduced, such as nanogenerators based on Zn O and thin and conformal energy harvester based on PZT. A detailed theoretical model of the flexible thin film energy harvester based on PZT nanoribbons is summarized, together with the in vivo demonstration of energy harvesting by integrating it with swine heart. Then the initial researches on stretchable energy harvesters based on piezoelectric material in wavy or serpentine configuration are introduced as well.
目的近年来,以纳米技术制造柔性可延能量收集装置(ultra-flexible energy harvester,UFEH)为能源的供应方法提供了新的思路。利用动物实验验证此类材料在生物体内的大范围应用需通过动物实验进行相容性验证。方法通过小型猪动物实验,研究UFEH在生物体内的工作状态,通过家兔对比实验,验证长期佩戴时生物体内相容性。结果于小型猪实验中,器件贴合良好,工作状态符合设计要求,贴合前后实验动物心功能相同,最高输出电压可达3V。在家兔对照实验中,实验组家兔存活时间与对照组一致,各项生理指标正常,未出现意外死亡、瘫痪、心功能下降等。结论压电设备于生物体内运行正常,对生物体组织伤害小,输出电压可达到商用级别;但仍需通过结合不同医用材料并对设备进行升级完善,可逐步完成生物体内长期植入目的。柔性可延展压电设备为体内收集机械能提供了新的思路与新的方法,符合我国自主创新的研究方向,为今后逐步实现能源清洁化,医用设备能源自给提供了可靠思路。
目的在生物体内柔性环境下测试微型纳米压电设备的延展性和弯曲性,为进一步研究提供动物实验数据。方法实验组和对照组家兔各20只,将微型柔性纳米压电器件缝合在实验组家兔心脏表面;对照组只进行开胸,不在心脏表面缝合器件。分别比较关胸前,术后1天和第1、2、3、4周时实验组和对照组家兔的体重、心率、呼吸、血压等生理指标,术后4周时心肌组织标本,以及实验前后柔性纳米压电芯片的物理性能。结果实验组家兔实验前后生理指标分别与对照组比较,差异均无统计学意义(P>0.05);对不同时刻重复测量的家兔体重、心率、呼吸和收缩压进行混合模型分析发现,在实验组和对照组两组间相比,P值分别为0.54、0.47、0.86、0.46,差异均无统计学意义;术后4周实验组与对照组家兔心肌组织切片的HE、Masson、CD 68和TUNEL染色均未发现病理性损伤,两组间相比差异无统计学意义;纳米压电芯片在实验组实验前后的能量收集性能差异无统计学意义(P>0.05);4周时,以光学和扫描电子显微镜(scanning electron microscope,SEM)观察芯片,均未发现表面断裂(P=1.00)。结论柔性纳米压电芯片在短期动物体内测试中运行良好,对家兔的基本生命指标无影响、对心肌组织无损伤,表明此纳米压电芯片具有较好的延展性和弯曲性,达到了在生物柔性组织环境内正常工作、无组织损害的基本要求。
Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sensors with important capabilities in this context,rendered in soft,ultrathin,‘skin-like’formats with numerous advantages over alternative technologies,including the ability to establish intimate,conformal contact without applied pressure,and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin.Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature,thermal conductivity,thermal diffusivity,volumetric heat capacity,and electrical impedance using simple analysis algorithms.Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.
Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.
Flexible inorganic bioelectronics represent a newly emerging and rapid developing research area.With its great power in enhancing the acquisition,management and utilization of health information,it is expected that these flexible and stretchable devices could underlie the new solutions to human health problems.Recent advances in this area including materials,devices,integrated systems and their biomedical applications indicate that through conformal and seamless contact with human body,the measurement becomes continuous and convenient with yields of higher quality data.This review covers recent progresses in flexible inorganic bio-electronics for human physiological parameters’monitoring in a wearable and continuous way.Strategies including materials,structures and device design are introduced with highlights toward the ability to solve remaining challenges in the measurement process.Advances in measuring bioelectrical signals,i.e.,the electrophysiological signals(including EEG,ECoG,ECG,and EMG),biophysical signals(including body temperature,strain,pressure,and acoustic signals)and biochemical signals(including sweat,glucose,and interstitial fluid)have been summarized.In the end,given the application property of this topic,the future research directions are outlooked.
