Chemically bonded flexible pressure sensor based on divergent metallic grid with high linearity, low hysteresis, and excellent stability

As intelligent robots and smart wearable electronics become commonplace, the demand for flexible pressure sensors is increasing rapidly. Despite the enormous effort in the development of flexible pressure sensor with high sensitivity, limited progress has been made in terms of developing a flexible pressure sensor with high linearity, low hysteresis, and high stability to avoid additional signal processing and signal distortion, and meanwhile promise good accuracy. Herein, we developed a flexible pressure sensor on foundation of the metallic strain effect. The divergent metallic grid was manufactured on polymide (PI) film with the mature magnetron sputtering and lift-off method, and a novel chemical bonding between PI and outer covering polydimethylsiloxane (PDMS) was developed for a flexible encapsulation. Benefiting from the excellent intrinsic properties of rigid sensitive materials and high-strength bonding. The as-fabricated pressure sensors exhibited several superior properties that are characterized by high linearity (linear regression coefficient of R² = 0.991) in whole sensing range (0–620 kPa), low hysteresis (2.78 %), rapid response/relaxation time (ca. 29/21 ms), remarkable durability (over 13,000 bending and stretching cycles), and excellent stability. The integrated merits of this novel pressure sensor were demonstrated in applications including human physiological signal monitoring, material identification, and pressure space mapping.