Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling.

Piezoelectric biomaterials have attracted great attention owing to the recent recognition of the impact of piezoelectricity on biological systems and their potential applications in implantable sensors, actuators, and energy harvesters. However, their practical use is hindered by the weak piezoelectric effect caused by the random polarization of biomaterials and the challenges of large-scale alignment of domains. Here, we present an active self-assembly strategy to tailor piezoelectric biomaterial thin films. The nanoconfinement-induced homogeneous nucleation overcomes the interfacial dependency and allows the electric field applied in-situ to align crystal grains across the entire film. The ß-glycine films exhibit an enhanced piezoelectric strain coefficient of 11.2 pm V-1 and an exceptional piezoelectric voltage coefficient of 252 × 10-3 Vm N-1. Of particular significance is that the nanoconfinement effect greatly improves the thermostability before melting (192 °C). This finding offers a generally applicable strategy for constructing high-performance large-sized piezoelectric bio-organic materials for biological and medical microdevices.

Van der Waals Exfoliation Processed Biopiezoelectric Submucosa Ultrathin Films.

Piezoelectric biomaterials have attracted significant attention due to the potential effect of piezoelectricity on biological tissues and their versatile applications. However, the high cost and complexity of assembling and domain aligning biomolecules at a large scale, and the disordered arrangement of piezoelectric domains as well as the lack of ferroelectricity in natural biological tissues remain a roadblock toward practical applications. Here, utilizing the weak van der Waals interaction in the layered structure of small intestinal submucosa (SIS), a van der Waals exfoliation (vdWE) process is reported to fabricate ultrathin films down to the thickness of the effective piezoelectric domain. Based on that, the piezoelectric property is revealed of SIS stemming from the collagen fibril, with piezoelectric coefficients up to 4.1 pm V-1 and in-plane polarization orientation parallel to the fibril axis. Furthermore, a biosensor based on the vdWE-processed SIS film with an in-plane electrode is demonstrated that produces open-circuit voltages of ≈250 mV under the cantilever vibration condition. The vdWE method shows great potential in facilely fabricating ultrathin films of soft tissues and biosensors.