Mechanical Properties Of Porous PDMS And Its Modulation On Flexible Electronic Devices' Stretchability

Flexible electronics is a kind of electronic technology that integrates components on flexible substrate,it has excellent flexibility and stretchability,which is different from traditional electronic technology.When flexible electronics is employed in clinic areas for long-term monitoring,porous material is usually used as substrate to ensure the heat and sweat penetration normally.Therefore,it is necessary to analyze the mechanical properties of porous material used in substrate and its modulation on the stretchability of flexible electronic devices.In this paper,the mechanical characteristics of the porous PDMS,which is usually used as flexible substrate,were studied experimentally and theoretically.After that,the stretchability modulation of flexible electronic devices with porous PDMS as substrate is discussed.The main contents of the article are as follows:(1)The mechanical properties of porous PDMS were measured by experimental test.It was found that the elastic modulus of PDMS decreases with the increase of porosity and increases with the temperature rises(from 0? to 40?).The storage modulus decreases with the increase of porosity,the loss modulus and loss factor are not sensitive to the porosity change,porous PDMS can endure long time deformation without stress relaxation.(2)The homogenization theory was used to analyze the mechanical characteristics of porous PDMS theoretically,and the results are compared with the experimental results.The results of two methods show a high consistency,which verifies that the theoretical model is effective and feasible.After that,the effect of pore size and porosity on the modulus of elasticity and Poisson's ratio of porous PDMS are further investigated,and an approximate formula for predicting the parameters of these materials is proposed.(3)On the basis of obtaining the mechanical parameters of porous PDMS,the effect of the porosity,thickness,encapsulation layer on the stretchability of the fully bonded serpentine structure was analyzed.The results show that porous PDMS substrate can effectively improve structural stretchability,while the geometric parameters such as substrate thickness has no obvious effect on stretchability.When the porous PDMS is used as a encapsulation layer,the decrease of the modulus of elasticity will lead to the decrease of the stretchability of the flexible electronics,but it is insensitive to the change of modulus(which is porosity change).In this paper,the mechanical properties of porous PDMS and its modulation on the stretchability of flexible electronic devices were studied.The results can provide a reference for the mechanical optimization of flexible electronics,related research work also provides new ideas for the optimal design of such devices.