Design of a Biaxially Stretchable Microstrip Antenna Enabled by Buckled Au Thin Film on an Elastomeric Substrate

Abstract

Wearable wireless biomedical electronics enable monitoring and wireless transmission of patient physiological and pathological signals to provide remote guidance for appropriate diagnosis and treatment. As a core component, the antenna must be flexible and stretchable to adapt to the complex mechanical deformations (e.g., stretching, bending, and twisting) induced by human motions. This work proposes a biaxially stretchable microstrip antenna based on buckled gold thin films bonded on an elastomeric substrate. A simplified analytic model validated by simulations and experiments is established to investigate the biaxial buckling behaviors of the thin films within 10% tensile strains. The properties, including resonance frequency, bandwidth, and radiation pattern of the fabricated biaxially stretchable microstrip antenna under various stretched states, are studied by combining experiments and finite element analysis. The effects of biaxial tensile deformations on the resonance frequency, bandwidth, and radiation properties are discussed. Results show that the designed microstrip antenna has a relatively stable performance under both natural and deformed states within 10% of uniaxial and biaxial tensile strains, which enables the designed antenna to have broad application prospects in wearable wireless medical devices for stable transmission of signals between body-worn sensors and terminals, especially for situations accompanied with complex deformations.