Highly tunable flexible AgCu/cotton pressure sensor using surface morphological engineering for enhanced performance

Engineering the active layer of pressure sensors with micro-nano structures is increasingly important in improving their sensing properties, such as sensitivity and detection range. However, existing structures based on template methods continue to face manufacturing challenges and uncontrolled structures, making it difficult to optimize sensing performance. To address the aforementioned shortcomings, this study proposes highly tunable metallic silver copper micro-nano structures adapted on cotton fabric (AgCu/cotton) to adjust the interfacial contact sites and optimize the sensing properties. The shape, size, and distribution of the metallic AgCu nano structures are precisely regulated, and various distinctive morphologies including two-dimensional (2D) nanosheet stacking, three-dimensional (3D) irregular protrusions, and nanoparticle aggregation were obtained. Specifically, the 3D irregular protrusions of varying heights and shapes (nanosheets, nanoparticles, and so on), encouraging multiple deformations and enhanced interfacial contact sites. On the other hand, the hierarchical porous structure of cotton fabric enhances structural compressibility. Collectively, the synergistic results of the 3D irregular protrusions and the hierarchical porous structure allow for a high sensitivity (115.65 kPa⁻¹), a quick response time (500 ms), and outstanding stability (2000 cycles). The above sensing properties enable the pressure sensor to be successfully applied in joint movement detection and swallowing recognition. The discovery could pave the way for a more cost-effective and widespread approach to a controlled and improved piezoresistive pressure sensor.

We herein develop a highly morphology-controlled AgCu/cotton flexible pressure sensor with an economical strategy toward superior sensing performance. Such regulated morphology is responsible for optimized contact sites and structural deformation, resulting in a high sensitivity of 115.65 kPa⁻¹ over 2–7.5 kPa, and showing great potential in various human motion detections.