Flexible and Ultrasensitive Piezoelectric Composites Based on Highly (00l)‐Assembled BaTiO3 Microplatelets for Wearable Electronics Application

Piezoelectric wearable electronics with flexibility and high sensitivity have received increasing attention in the fields of health monitoring, flexible robots, and artificial intelligence. Here, a flexible organic–inorganic hybrid composite for wearable electronics application based on (00l)‐aligned BaTiO3 (BT) single‐crystal microplatelets is prepared by layer‐by‐layer self‐assembly technology. For the polyvinylidene fluoride‐trifluoroethylene (P(VDF‐TrFE))/BT single‐crystal microplatelets composite film, the sensitivity is nearly 20 times higher than that of its counterparts of P(VDF‐TrFE)/BT microparticles composite film and pure P(VDF‐TrFE) film. The orderly alignment of BT microplatelets also has been found advantageous to the strength of the composite film. The tensile strength is up to 204.3 MPa even at a high inorganic phase content of 53.8 wt% in P(VDF‐TrFE)/BT single‐crystal microplatelets composite film, which is four times that of pure P(VDF‐TrFE) film. Moreover, the flexible piezoelectric wearable device based on P(VDF‐TrFE)/BT single‐crystal microplatelets film effectively provides detailed information for monitoring human activities such as pronunciation, frequency, and waveform of pulse beating, and motion states. This high sensitivity, high strength, and flexible piezoelectric composite provides much potential on the applications of wearable equipments and health monitoring devices. A flexible organic–inorganic hybrid piezoelectric sensor based on (00l)‐aligned BaTiO3 (BT) single‐crystal microplatelets with almost 100% Lotgering factor is prepared by layer‐by‐layer self‐assembly technology. In the compressive force range of 3–30 Pa, the sensitivity of polyvinylidene fluoride‐trifluoroethylene/BT single‐crystal microplatelets composite film is 27.09 kPa−1, which is much higher than those reported in most of previous literatures.