With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, “green” electrically conductive Ag nanowire (AgNW)/cellulose nanofiber (CNF) hybrid nanopaper was fabricated to prepare flexible sensors using the facial solution blending and vacuum filtration technique. The amphiphilic property of cellulose is beneficial for the homogeneous dispersion of AgNW to construct effective electrically conductive networks. Two different types of strain sensors were designed to study their applications in strain sensing. One was the tensile strain sensor where the hybrid nanopaper was sandwiched between two thermoplastic polyurethane (TPU) films through hot compression, and special micro-crack structure was constructed through the pre-strain process to enhance the sensitivity. Interestingly, typical pre-strain dependent strain sensing behavior was observed due to different crack densities constructed under different pre-strains. As a result, it exhibited an ultralow detection limit as low as 0.2%, good reproducibility under different strains and excellent stability and durability during 500 cycles (1% strain, 0.5 mm/min). The other was the bending strain sensor where the hybrid nanopaper was adhered onto TPU film, showing stable and recoverable linearly sensing behavior towards two different bending modes (tension and compression). Importantly, the bending sensor displayed great potential for human motion and physiological signal detection. Furthermore, the hybrid nanopaper also exhibited stable and reproducible negative temperature sensing behavior when it was served as a temperature sensor. This study provides a guideline for fabricating flexible and biodegradable sensors.

随着智能可穿戴设备的快速发展，迫切需要柔性和可生物降解的传感器。在这项研究中，制造了“绿色”导电Ag纳米线（AgNW）/纤维素纳米纤维（CNF）混合纳米纸，以使用面部溶液混合和真空过滤技术制备柔性传感器。纤维素的两亲特性有利于AgNW的均匀分散，以构建有效的导电网络。设计了两种不同类型的应变传感器来研究其在应变传感中的应用。一种是拉伸应变传感器，通过热压缩将杂化纳米纸夹在两张热塑性聚氨酯（TPU）膜之间，并通过预应变过程构造了特殊的微裂纹结构以提高灵敏度。有趣的是 由于在不同的预应变下构造了不同的裂纹密度，因此观察到典型的依赖于应变的应变行为。结果，它显示出低至0.2％的超低检测限，在不同应变下的良好重现性以及在500个循环（1％应变，0.5 mm / min）下极好的稳定性和耐久性。另一个是弯曲应变传感器，其中杂化纳米纸粘附在TPU膜上，显示出针对两种不同弯曲模式（张力和压缩）的稳定且可恢复的线性传感行为。重要的是，弯曲传感​​器在人体运动和生理信号检测方面显示出巨大的潜力。此外，当杂化纳米纸用作温度传感器时，它还表现出稳定且可再现的负温度感测行为。