Flexible, ultralight, ultrathin, and highly sensitive pressure sensors based on bacterial cellulose and silver nanowires

Flexible and ultrathin pressure sensors have received significant attention in applications of health monitoring, artificial skin, human–machine interfaces, soft robotics, etc. Bacterial cellulose (BC) is a renewable resource widely used in tissue engineering and flexible pressure sensors owing to its excellent biocompatibility. In this study, after simple mixing (mass ratio 1:1) and freeze-drying of BC and silver nanowires (AgNWs) suspensions, cylindrical BC-AgNWs aerogels (ф = 14 mm, h = 1.6 mm) were obtained. The BC-AgNWs aerogels showed a porous and fluffy structure with an ultralight mass of 3.2 mg. After compression, ultrathin (30 μm) BC-AgNWs films could be easily fabricated. The BC-AgNWs films had excellent mechanical properties and an ultrahigh sensitivity of 47.1 mA kPa−1 V−1. Ultrathin (~ 40 μm) flexible pressure sensors were assembled by encapsulating the BC-AgNWs films between 1-μm-thick polyethylene terephthalate (PET) films. The assembled PET/BC-AgNWs film/PET pressure sensors had a detection limit of 400 Pa and a fast response time of 220 ms. Moreover, the sensors were used to detect human motions such as finger bending, wrist bending, elbow bending, finger pressing, swallowing, and squatting, showing good application prospects in the field of health monitoring.