Batch Fabrication of Flexible Strain Sensors with High Linearity and Low Hysteresis for Health Monitoring and Motion Detection.

In recent years, flexible strain sensors have gradually come into our lives due to their superiority in the field of biomonitoring. However, these sensors still suffer from poor durability, high hysteresis, and difficulty in calibration, resulting in great hindrance of practical application. Herein, starting with interfacial interaction regulation and structure-induced cracking, flexible strain sensors with high performance are successfully fabricated. In this strategy, dopamine treatment is used to enhance the bonding between flexible substrates and carbon nanotubes (CNT). The combination within the conductive networks is then controlled by substituting the CNT type. Braid-like fibers are employed to achieve controllable expansion of the conductive layer cracks. Finally, we obtain strain sensors that possess high linearity (R2 = 0.997) with low hysteresis (5%), high sensitivity (GF = 60) and wide sensing range (0-50%), short response time (62 ms), outstanding stability, and repeatability (>10,000 cycles). Flexible strain sensors with all performances good are rarely reported. Static and dynamic respiration and pulse signal monitoring by the fiber sensor are demonstrated. Moreover, a knee joint monitoring system is constructed for the monitoring of various walking stances, which is of great value to the diagnosis and rehabilitation of many diseases.

Hierarchical Mn3O4/Graphene Microflowers Fabricated via a Selective Dissolution Strategy for Alkali-Metal-Ion Storage.

Mn3O4 is a potential anode for alkali-metal (Li/Na/K)-ion batteries because of the high capacity, abundant resources, and eco-friendliness. However, its ion storage performance is limited by poor electronic conductivity and large volume expansion during the charging/discharging process. In this study, we presented a facile dissolution strategy to fabricate ultrathin nanosheet-assembled hierarchical Mn3O4/graphene microflowers, realizing enhanced alkali-metal-ion storage performance. The synthetic mechanism was proven as the selective dissolution of vanadium via controlled experiments with different reaction times. The as-synthesized composites showed high lithium storage capacity (about 900 mA h g-1) and superior cyclability (∼400 mA h g-1 after 500 cycles). In addition, when evaluated as a Na-ion battery anode, the reversible capacity of about 200 mA h g-1 was attained, which remained at 167 mA h g-1 after 200 cycles. Moreover, to the best of our knowledge, the potassium storage properties of Mn3O4 were evaluated for the first time and a reversible capacity of about 230 mA h g-1 was achieved. We believe that our findings will be instructive for future investigations of high-capacity anode materials for alkali-metal-ion batteries.