Research On Paper-based Flexible Conductive Wires Fabricated With Room Temperature Liquid-metal Films

A paper-based electronic device is a kind of flexible electronic devices,which is based on the environmental and economic substrate-paper.Compared to flexible electronic devices which are based on organic polymer substrates,paper-based electronic devices can work normally under deformation,and can be dealt convenient without any environmental pollution and resource waste.Therefore,developing paper-based electronic devices must be one of important directions of developing flexible electronic devices.As the core of paper-based electronic devices,paper-based flexible conductive wires are the key to interconnect flexible components and communicate among paper-based electronic devices.So the paper-based flexible conductive wires are obviously important.But at present,paper-based flexible conductive wires are not equipped with high conductivity and high reliability at the same time.One of important solutions to solve this problem is to make room temperature liquid metals work as conductive materials of paper-based flexible wires.However,large surface tension of liquid metals and difficulties for fabricating liquid metals into films are the technological bottlenecks for fabricating paper-based liquid-metal flexible wires,which limit their practical application.According to this,the preparation methods of paper-based liquid-metal flexible wires,their variation law of resistance change under external stress,their fatigue and their temperature stability were discussed in this paper.Besides,the application of paper-based flexible wires on flexible interconnect and flexible functional devices was explored,and the main results were list as follows:(1)Research on fabricating technology of paper-based films with controllable thickness and paper-based flexible conductive wires with high conductivity.The solution of liquid-metal microparticles was prepared by ultrasonic method and deposited on the surface of paper substrates to form liquid metal films.The thickness of paper-based liquid-metal films could be controllable range from 7 ?m to 115 ?m via regulating the amount of deposited liquid-metal microparticles.Then paper-based liquid-metal wires,with high conductivity(3.8×104 S/cm),were prepared via mechanical sintering paper-based liquid-metal films creatively.(2)Research on conductive reliability and stability of paper-based flexible conductive wires under external strain condition.The resistance change of paper-based flexible wires under bending and folding conditions,the conductive reliability and stability of paper-based flexible wires and liquid-metal films under folding cycles,the conductivity stability after being exposed to the air for a long time,and the conductive stability under different temperature were studied.The results showed that : the resistance of paper-based flexible wires was approximately inversely proportional to the bending radius was decreasing,and the resistance was only changed 0.31 ?compared to the initial resistance;the paper-based liquid-metal film was still insulate with the resistance of 1.2×109 ? and the wire is conductive with little resistant change(<5%)even after 10000 folding cycles;the resistance of paper-based flexible wires was only changed 0.02?when the temperature was changed from-30 ? to 107 ?.All this results proved the conductive reliability and stability of paper-based flexible wires under any condition.(3)Research on practical application and recycle properties of paper-based flexible conductive wires.Then practical application and waste treatment paper-based flexible wires were explored in the paper.It was found that electronic components worked normally in the circuits composed of paper-based flexible wires even under bending condition,and the waste of paperbased flexible wires could be recycled by NaOH solution with a high recycling rate up to 95.6%.This proved practical application value of paper-based flexible wires again.