Electromechanical Design of Self‐Similar Inspired Surface Electrodes for Human‐Machine Interaction

Abstract

Stable acquisition of electromyography (EMG)/electrocardiograph (ECG) signal is critical and challenging in dynamic human-machine interaction. Here, self-similar inspired configuration is presented to design surface electrodes with high mechanical adaptability (stretchability and conformability with skin) and electrical sensitivity/stability which are usually a pair of paradoxes. Mechanical and electrical coupling optimization strategies are proposed to optimize the surface electrodes with the 2nd-order self-similar serpentine configuration. It is devoted the relationship between the geometric shape parameters (height-space ratio η, scale factor β, and line width w), the areal coverage α, and mechanical adaptability, based on which an open network-shaped electrode is designed to stably collect high signal-to-noise ratio signals. The theoretical and experimental results show that the electrodes can be stretched > 30% and conform with skin wrinkle. The interfacial strength of electrode and skin is measured by homemade peeling test experiment platform. The surface electrodes with different line widths are used to record ECG signals for validating the electrical stability. Conformability reduces background noises and motion artifacts which provides stable recording of ECG/EMG signals. Further, the thin, stretchable electrodes are mounted on the human epidermis for continuous, stable biopotential signal records which suggests the way to high-performance electrodes in human-machine interaction.

Dry Electrodes for Human Bioelectrical Signal Monitoring

“…However, the high cost in electrode fabrication and the requirement of wires for connecting to the subcutaneous electrodes during measurement makes them susceptible to infection. Huang et al [ 101 ] designed a self-adsorbing capacitive electrode using PDMS as a substrate material. The electrode possessed a sandwich structure, with a 0.3-micron Au film sandwiched between two 1.2-micron PI films.…”

Soft Elastomers with Programmable Stiffness as Strain-Isolating Substrates for Stretchable Electronics

“…Stretchable electronics are of rapidly increasing interest due to their ability to function under complex deformations and yield numerous important applications such as wearable electronics, − curvilinear electronics, − and biointegrated real-time health monitoring devices. − To realize stretchable electronics, strain isolation/protection of stiff functional components from external deformations represents the most effective design strategy. − Delicate designs of the heterogeneous substrate with spatiocontrolled stiffness including embedding stiff platforms within the soft substrate, − introducing stiff patterns on the soft substrate, , introducing ultrasoft materials on the surface of the soft substrate, and introducing liquid-filled cavities in the soft substrate have been explored to enable the strain isolation/protection of functional components. However, all of these designs either involve noncompatible fabrication processes with the well-established lithographic process or require complex optimization schemes to achieve a large stretchability.…”

Wearable strain sensors: state-of-the-art and future applications

“…37,38 In such a flexible system, information on mechanical deformation has always been an important research topic. [39][40][41][42] The gauge factor of a strain sensor is low to facilitate a higher strain sensing range. Further, the mechanical properties of fundamentally fragile materials are incompatible with those of textiles for integrated systems.…”