Preparation And Properties Of Polylactide-based Piezoelectric Thin Films

The various application of 5G communication technology promotes the rapid development of the Internet of things(Io T),which require higher standards for the system power supply and information interaction(intelligent sensing)in different scenarios.Piezoelectric devices based on piezoelectric materials are used as integrated energy harvesting and smart sensing devices,which has received numerous interest from researchers.Wherein,the piezoelectric device based on polylactide film,which possesses flexibility,renewable,biodegradable,biocompatible,and other superior characteristics,have great potential in the development of smart sensing and energy harvesting fields.In this paper,the flexible PLA/VB₂ composite piezoelectric films with high voltage performance,renewable and degradable were prepared by the doping PLA with riboflavin(VB₂)and slit coating approach.The interface interaction between PLA and VB₂molecules improves the crystallinity of PLA,which further enhancing the piezoelectric properties of the PLA/VB₂ composite piezoelectric film.PLA/VB₂ composite piezoelectric film devices realizes the application in energy harvesting,human joint motion recognition,and voice recognition.The detailed research contents are as follows:(1)The flexible PLA/VB₂ composite piezoelectric film with high piezoelectric performance is prepared through VB₂ doping and slit coating,and the thickness uniformity is less than 5%.By XRD,DSC,FTIR,SEM,and so on,we found that both the crystalline properties and piezoelectric properties of PLA firstly increased and then decreased with the increase of the content of VB₂ in PLA.It is clarified about the influence mechanism that the interface interaction mechanism of VB₂ and PLA improved the crystalline properties of PLA to improve the piezoelectric properties of PLA.At the same time,it is found that the composite piezoelectric film shows the best crystalline and piezoelectric properties when the content of VB₂ is 18 wt%in PLA/VB₂.After optimizing the device preparation and packaging process,the reliability of the PLA/VB₂(18 wt%)piezoelectric device was improved,and a good piezoelectric response was achieved under the excitation of mechanical force and acoustics.Furthermore,the PLA/VB₂(18 wt%)piezoelectric device has a maximum peak power density of 75.68 m W/cm³ when the loading resistance is 28 M?,which is 28.7 times higher than that of a pure PLA piezoelectric device.(2)The application of PLA/VB₂(18 wt%)piezoelectric device in energy harvesting,human joint action recognition and voice recognition was explored:The energy harvester can collect and transform the kinetic energy of wind and raindrops to electricity that can light up three LED lights;The human motion sensor is attached to human knuckles,elbow joints,knee joints,which can quickly respond to joint motion;The voice recognition sensor can accurately perceive the seven basic tones of piano(Do,Re,Mi,Fa,So,La,Si),and the relative error of less than 1%between the output frequency and the standard tone frequency;The voice recognition sensor can realize the human voice recognition through the acquisition and determination of the voice characteristic frequency;Based on the attenuation characteristics of sound in the air,the two-dimensional sound source localization sensor can realize the localization of sound source in plane.