Electrospun fiber-based high-performance flexible multi-level micro-structured pressure sensor: Design, development and modelling

Geometric microengineering is an effective approach to improve the comprehensive performance of pressure sensors. Unfortunately, the design of multi-level microstructure and the development of industrially relevant technology remain challenging. In this study, template-assisted electrospinning is applied to fabricate the multi-level microstructured TPU membranes with both regularly distributed knoll-like microstructures on the surface and randomly distributed fiber-network structures inside, which serve as the active layers of the pressure sensor. The assembled pressure sensor shows exceptional performance, including ultralow detection limit of 0.7 Pa, high sensitivity of 63.93 kPa−1, a wide sensing range of 0–160 kPa and excellent durability of >10000 cycles. The sensing mechanism is further investigated based on the equivalent circuit diagram analysis and finite element analysis (FEA). In FEA, the building block approach is adopted to simulate the electro-mechanical performance between complex fiber networks. These results reveal that the knoll-like microstructures and fiber-network structures lower the effective elastic modulus and increase the contact points/areas or conductive path upon loading, thereby responsible for the exceptional sensing performance. Real-time monitoring of human physiological signals is demonstrated. The industrial relevance of the template-assisted electrospinning technology for fabricating pressure sensors is highly scalable, thus industrially relevant.