Flexible conductive Ag nanowire/cellulose nano?bril hybrid nanopaper for strain and temperature sensing applications

柔性银纳米线/纤维素纳米纤维导电复合纳米纸用于应变和温度传感器

With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, ‘‘green" electrically conductive Ag nanowire (Ag NW)/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 Ag NW 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.

本文以"绿色"纤维素纳米纤维(CNF)为基体,银纳米线(Ag NW)为导电填料,采用溶液共混-真空抽滤工艺制备了柔性银纳米线/纤维素纳米纤维导电复合纳米纸,并研究了其在应变和温度传感器方面的应用.采用热压成型工艺制备了以该导电复合纳米纸为导电夹层的"三明治"结构拉伸应变传感器,并通过预应变处理工艺在其内部成功构建了超灵敏的"微裂纹"结构,使其具有高灵敏度、超低的探测限(0.2%)、良好的稳定性、重复性和耐疲劳性.当该导电复合纳米纸作为弯曲传感器时,其对不同的弯曲模式具有不同的响应性能,具有优异的可识别性.同时,其对外场温度还具有特殊的"负温度效应",且具有优异的稳定性和可回复性.因此,该"绿色"导电纳米复合纳米纸在制备新型应变和温度传感器方面具有巨大的应用潜力.