Design Of Flexible/stretchable Microsupercapacitor Arrays And Their Application In Integrated Wearable Electronics

Flexible/stretchable electronic devices,such as electronic skin,nanoronot,embeddable armarium,sensors,etc.,have attracted much attention due to their properties of high integration,multifunction,comfort and good security.To fufill these feature,the cossresponding energy storage should be redesigned into flexible or stretchable form to meet the new requirement of wearable devices.Micro supercapacitor that possess remarkable features of small size,varied structures,high security and skin-touched properties have become a promising choice of energy supply.However,it has a late start and short development history,this will require us to optimize structure,develop novel electrode materilas and gel electrolyte aimed at improving the electrochemical performance and practical application value.Based on the choice of flexible/stretchable substate,synthesis of electrode materials,optimization of electrode structures,development of gel electrolyte et al.,this dissertation aims at fabricating high performance micro supercapacitor and expanding its applications form in wearable electronics.For the choice of substrate,we used PET,PMMA,PDMS etc.as flexible or stretchable substrate to fabricate devices;in terms of electrode materilas,a series of nanomaterilas with high performance were synthesized by employing elecrospinning,electrodepositon,hydrothermal,chemical vapor deposition method;as for electrode structure,1D fiber structure and 2D configuration were designed.Moreover,we fabricated multifarious self-driven integrated sensing system and in-suit analysis/display unit to realize the practical application of micro supercapactitor.It mainly includes:1.NiFe₂O₄ nanofibers were synthesized by using elecrospinning method,then conventional photolithographic process was used to fabricate flexible interdigital in-plane micro supercapacitors on PET substrate.The assembled NiFe₂O₄ nanofiber based micro supercapacitors exhibited a specific capacitance of 2.23 F/cm³ at the scan rate of 100 mV/s,robust cycling stability with a capacitance retention of 93.6%after10000 charge/discharge cycles,superior flexibility and outstanding stability even under the different bending states varing from 30°to 180°.Morover,the graphene pressure sensor powered by the fabricated micro supercapacitor showed a stable response to pressure signal,which is in good agrrement with the simulated results by MATLAB,demonstrating its fessibility and reasonability of the integrated self-driven system.2.A facile electrodepositon and etch approach were proposed to prepare micron hollow polypyrrole（PPy）sleeve electrode and then a new type of coaxial fiber SC was assembled on the basis of the theoretical results simulated by MAXWELL.The designed device showed a large volume capacitance of 2.44 F/cm³,which is 5.14times higher than that of twisted fiber SCs,fitting well with the theoretical results simulated by ANSYS Maxwell software.An integrated system consists of the fabricated SCs as power source and CuInS₂ film photodetector as functional units was then presented and weave into a form of smart ring.As-designed self-driven smart ring exhibited stable photo-current response to white light and excellent flexibility,demonstrating the feasibility of the 1D wearable integrated system.3.A intergrated wearable gas sensor and in situ concentration analysis/display system driven by micro-supercapacitor array was designed,which cosists of polypyrrole（Ppy）film based concentric circle micro supercapacitor array as energy supply,a MWCNT/PANI room temperature gas sensor as functionalized units,a PCB-signal processing component,a bluetooth as data transmission module and a phone as analysis/display terminal.The designed micro supercapacitor with concentric circles structure exhibited a large areal capacitance of 47.42 mF/cm².As-fabricated self-driven room temperature ethanol gas sensor showed a quick response time（13s）and recovery time（4.5s）.When the gas sensor exposed to ethanol gas,the real-time result was displayed in mobile APP.The outstanding performance of the designed intergrated system suggests its wide application in personalized monitoring drunken driving or detection of ethanol gas in industry.4.Highly stretchable micro-supercapacitor arrays based on wave-shaped hybrid multiwalled carbon nanotubes/polyaniline electrodes were successfully fabricated on the PDMS substrate.First,we used a 3D printer to make a mold with a convex wavy electrode based on photosensitive acrylate resin.After transfer printing,injection of the elctrode slurry,coating electrolyte and encapsulation process,the micro-supercapacitor arrays were messured by electrochemical workstation,which showed a large areal capacitance of 44.13 mF/cm² and offered a power density of 0.07mW/cm² at an area energy density of 0.004 mW h/cm².A red light-emitting diode can be easily lighted under different conditions including stretching,twisting,crimping,and winding.