One-Step Patterned Contact-Resistance-Free Stretchable Strain Sensors With High Linearity and Repeatability for Body-Motion Detection

Most of the resistive-type stretchable strain sensors exhibit large sensing ranges and high sensitivity but suboptimal repeatability and linearity because of the contact-resistance mechanism. To achieve high repeatability and linearity, several sensors with contact-resistance-free structures are proposed. However, due to the different geometric layouts of the conductive materials and the insulating substrates, the patterning of these sensors requires multiple processes including photolithography and etching, which may cause high costs and are not suitable for consumer wearable applications. Here, we report a design for stretchable strain sensors based on a one-step patterned contact-resistance-free structure, i.e., the independent-sensing-and-stretchable-function structure (ISSFS). The stretchability mainly comes from the overall large deformation of the wide curved segments (the stretchable parts), while the resistance variation is mainly attributed to the tensile strain of the narrow straight segments (the sensing parts). High linearity (R² = 0.999) and repeatability (repeatability error = 1.44%) are achieved because neither unstable contact resistance nor nonlinear constitutive and geometric behaviors occur during the sensing process. The conductive materials and the insulating substrates do not need to have different geometric layouts; thus, they can be patterned by only one-step laser cutting. The proposed sensors show great potential in body-motion detection for wearable devices.