Electrical Metamaterial‐Based Interconnects‐Enabled Highly Stretchable Wireless Electrocardiography Circuit

Abstract Advancement of truly stretchable wireless circuits is crucial for the development of high‐fidelity wearables for health monitoring, human‐machine interfaces and body‐sensor network applications. Reported stretchable wireless circuits are capable of reliable functioning under tensile strain of up to 30%, which is not sufficient for applications on the parts of the body with greater deformation. Here, a novel strategy is reported for forming highly stretchable interconnects, namely electrical metamaterial‐based interconnect (EMI), that can be integrated with electronic components to develop complex stretchable circuits for various applications including wearables. EMIs are 3D microfluidic channels embedded in hyperelastic polymers, filled with liquid metal, gallium indium (GaIn). Unlike other metal conductors and liquid metal‐based interconnects reported so far, EMI shows metamaterial‐like property of reduction of its electrical resistance under strain. Using EMIs a highly stretchable wireless electrocardiography wearable is developed that functions reliably under up to 100% strain. The circuit includes amplifiers, filters, Bluetooth components, and a rechargeable battery and attaches to soft sensor patches via magnetic connectors. The use of the soft and stretchable circuit with the Young's modulus of 0.65 MPa along with soft sensors results in minimizing the motion artifacts significantly making it ideal for reliable long‐term health monitoring.