Self-similar Design And Human-machine Interaction Of Stretchable Surface Electrodes

Stretchable surface biological electrode is one typical epidermal electronic device,which is widely applied to biological health monitor and human machine interaction.The key is the stretchability analysis and conformal contact mechaism.The thesis would focus on the order-2 self-similar serpentine design and optimized structural design for improving output electrical performance and biological monitoring application of sEMG electrode.The contributions of the thesis are introduced as the follows:The scale regular model is built for the stretchability of the order-2 self-similar serpentine structure.Through the theoretical analysis,FEM simulation and experiment research methods,it is devoted the relationship between the stretchability and the geometry parameters,height/length ratio,space/space ratio,thickness,width and yield strain,which is used to predict the sretchability of the order-2 self-similar serpentine structure.2D interfacial mechanic model of the electrode on the checkerboard buckling patterns of the skin is built based on energy variation method.The criterion for is proposed to determine the electrode is conformal contact with skin surface or not.Skin roughness,material and geometry size of the substrate are considered to evaluate interfacial behavior at electrode/the skin surface.The interfacial mechanic behavior is also studied in the case upon applying external loadings,which provides the electrode an interfacial delamination method from the skin surface.Contact behavior at the electrode/skin interface has been validated by experiments with different substrate thicknesses,areal coverages and external loadings.The geometry parameter effects of surface electrode for stretchability,conformability,areal coverage and output signal gain are studied.The mechanical deformability and electrical performance coupling optimization model is built with stretchability and conformability constraints.The electrode is optimized to improve the electrical performance of sEMG electrode with self-similar serpentine structure for satisfying larger deformation and conformally contact with the skin surface.The geometry parameter scale span is provided to optimize the electrode.The evaluation factors(SNR,background noise,output gain)are proposed to promote the performance of stretchable electrodes.The PVA sacrificial layer technique is proposed to transfer print the electrode to the skin surface.Compared with PDMS substrate,the critical energy release rate has decreased 60%with PVA water solution adhesive.And the improving method with the PVA/PDMS substrate provides larger process windows of transfer printing.The application to the biological health monitor and human machine interaction of the optimized structural electrode is explored.Physiological signals from different parts of the body with sharp curvature,such as wrist,index finger and face are recorded by the stretchable capacitive electrode,which are not recorded by the traditional electrode.It expands the application area,and exhibits great potential in applications in healthcare monitoring and human-machine interface to control the motion of the mobile robot.