Electrostatic Assembly of Laminated Transparent Piezoelectrets for Epidermal and Implantable Electronics

Abstract

Piezoelectric polymers hold physical properties, such as high mechanical flexibility and smaller acoustical impedance, that piezoelectric ceramics do not have. Nevertheless, owing to the piezoelectricity originates from the crystalline region, it is still a challenge for most semi-crystalline polymers to generate a high piezoelectric response. Here, we develop a class of piezoelectret with sandwiched polymer structure (electret/dielectric/electret, EDE) which is assembled via simple electrostatic interaction. The transparent and mechanical robust EDE piezoelectrets exhibit the piezoelectric constant ( d 33 ) up to ~930 pC N -1 , and the corresponding physical model is established to investigate major influence factors to the piezoelectric properties, including the relative permittivity and elastic modulus of the electret and dielectric, and the simulated results are in accord with the experimental data. We demonstrate the strain sensors and acoustic transducers based on the ultrathin and flexible EDE piezoelectret, verifying the feasibility of the electrostatic assembled piezoelectrets in the applications of epidermal and implantable electronics. Moreover, various combinations of polymers in the EDE structure can be employed based on our proposed model to explore other unique applications such as transient electronics. A class of transparent piezoelectret with sandwich hybrid polymers and parallel-aligned dipoles is developed via simple electrostatic self-assembly, and the corresponding physical model is established to guide the optimization of the piezoelectric performance. As the advancement in flexible piezoelectric film, this study shows the applications and prospects in strain sensors and acoustic transducers for epidermal and implantable electronics. • A sandwich piezoelectrets with high piezoelectricity and transparency are developed via electrostatic self-assembly. • Excellent mechanical durability and thermal stability (up to 450 K) have been achieved. • The proposed physical model can guide the design of the piezoelectrets using different polymer combinations. • Wearable and implantable devices based on the flexible piezoelectrets have been demonstrated.