The Design,Fabrication And Application Of Liquid Metal-based Flexible Electrodes And Circuits

Flexible electronics have attracted widespread attention due to their ability to maintain the function upon various deformations.In general,there are two ways to achieve the flexible electronics.One is designing flexible structures that allow deformation,the other is that using conductive materials that are intrinsically soft.Eutectic gallium-indium(EGaIn),a kind of stable,safe,nontoxic,low melting point liquid metal,is an ideal candidate for flexible electronics due to its soft,fluidity,moldability and excellent conductivity.Many studies have been devoted to develop techniques for fabricating liquid-metal electrodes and circuits.One of these techniques is patterning of liquid metal.There are some methods to pattern liquid metal including lithography,injection,subtractive and additive.However,these methods are limited to complicated procedures,high cost and low resolution.In this dissertation,a novel strategy was developed to pattern liquid metal for electrodes and circuits.The main results are as follows:(1)A lithography-based,defect-free,high-resolution patterning method was developed to fabricate.In this method,microfluidic channels were used as mould,and polydimethylsiloxane(PDMS)or polyethylene terephthalate(PET)film coated with PDMS as flexible substrates.The liquid metal was first dispensed into an air plasma-treated substrate through a reversibly sealed PDMS microchannel.The liquid metal-filled substrate was then placed on a cold plate,where the liquid metal was solidified.Finally,defect-free patterns were obtained by directly peeling off the PDMS microchannel on a hot plate.The as-made liquid metal patterns exhibited excellent electrical and mechanical performance,which can maintain low resistances even under reduplicative bending or twisting.(2)Three kinds of flexible electronics were fabricated,including liquid metal electrode-based capacitive sensor,liquid metal coil for near field communication and wireless power transmission,and liquid metal circuit board-based microcontroller system.There electronics can work even upon deformations because of the soft,connective liquid metal.According to these applications,we demonstrated the widely applicability of liquid metal pattern,and proved that this simple,efficient method is valuable in flexible electronics,especially in the design,fabrication and application of liquid metal electrode and circuit.