Dynamic Characteristics Of Flexible Electronic Devices On Porous PDMS Substrates

Extensible flexible electronic technology has become a research hotspot in the electronics industry and academia in recent years.The most obvious advantage is that it can withstand complex deformation such as stretching,bending,folding,etc.,while ensuring circuit stability.The flexible substrate used in clinical medical flexible electronic devices should meet the normal exchange of physiological elements of the human body(such as the flow of trace elements in the body,sweat and heat emissions from the body)to reduce the impact on the normal physiological activities of the human body.The application of porous substrates provides a way to solve this problem.In addition,the application environment of flexible electronic devices is often complex and dynamic,and may be subjected to random loads such as impact and dynamic stretching,so the dynamic characteristics of flexible electronic devices need to be further evaluated.The main research contents of this article are as follows:(1)The dynamic mechanical parameters of the porous PDMS material under the generalized Maxwell viscoelastic constitutive model were obtained by DMA dynamic testing and least square fitting.The viscoelastic properties of porous PDMS materials under the conditions of porosity,frequency,temperature,strain amplitude and other factors were measured by DMA dynamic test;the generalized Maxwell constitutive model was selected to describe the viscoelastic mechanical behavior of porous PDMS materials,and the least square method The test data is fitted to obtain the viscoelastic parameters of the material in the form of Prony series.(2)The deformation characteristics of flexible electronic devices using porous PDMS as the base material during dynamic stretching were analyzed.Using the finite element method and considering the viscoelastic properties of the substrate or the encapsulation layer,the stretchability of the porous PDMS substrate serpentine wire structure under different loading strain rates was analyzed.The results show that the improvement effect of the substrate porosity on the structural stretchability gradually decreases with the increase of the loading strain rate,and with the increase of the substrate porosity,the degree of structural stretchability deterioration increases;The degree of degradation increases slightly with the increase of porosity,and is at the same level as the degradation factor of the structure that does not contain the encapsulation layer.The maximum strain of the metal wire gradually decreases with the relaxation time.When the relaxation phase is completed,the maximum strain in the metal wire remains at a relatively high level.(3)A model for analyzing the structure of a flexible electronic straight wire island bridge considering an elastic substrate is established.Geometrical nonlinearity is introduced and a strict governing equation is established to analyze its buckling behavior and free vibration.Using the method of comparative analysis between the analytical model and the finite element results,the regulation effect of different factors on the natural frequency of the flexible base island bridge structure was studied.The results show that the degree of prestretching of the substrate has almost no effect on the natural frequency of the elastic substrate island bridge structure;the application of the porous PDMS substrate can effectively adjust the natural frequency of the island bridge structure;the substrate material properties and geometric parameters are inherent to the flexible substrate island bridge structure The adjustment effect of frequency is more significant.The research results of this paper can provide guidance for the optimization of mechanical properties of flexible electronic devices,and have reference significance for the design and application of flexible electronic products.