Roll‐to‐Roll Production of Novel Large‐Area Piezoelectric Films for Transparent, Flexible, and Wearable Fabric Loudspeakers

Abstract

High‐performance flexible loudspeakers have the potential to revolutionize the future of flexible/wearable electronics by providing this long‐sought function. Here, a novel method is developed to produce large‐area, flexible, and transparent piezoelectric loudspeakers, where both piezoelectric lead zirconate titanate (PZT) nanoparticles and graphene nanoplatelets (GNPs) are simultaneously aligned in the thickness direction forming dense “nanocolumn forests.” The preferential alignment of the particles not only reduces filler concentration and improves the piezoelectric performance, but also provides transparency to the film by enabling light to travel with little scattering or absorption in the thickness direction. Its potential applications, such as wearable and portable personal audio systems, along with a 9‐ft‐tall immersive walk‐through soundscape structure, are also demonstrated. The performance and the directivity of each loudspeaker are characterized through sound pressure level (SPL) versus frequency measurements over human audio spectrum (20 Hz–20 kHz) in an anechoic chamber. Furthermore, scalability of this unique roll‐to‐roll process is demonstrated on a 44‐ft‐long custom designed roll‐to‐roll (R2R) manufacturing line that can produce these six‐inch‐wide multifunctional films continuously.

All‐Organic Flexible Ferroelectret Nanogenerator with Fabric‐Based Electrodes for Self‐Powered Body Area Networks

“…[ 45,46 ] PEDOT:PSS has been applied in wearable devices such as fabric‐based antennas, [ 47 ] flexible supercapacitors [ 48 ] and portable loudspeakers. [ 49 ] Maity et al. [ 50 ] fabricated an all‐organic PENG by coating PEDOT electrodes onto a PVDF film via vapor‐phase polymerization.…”

“…Considering the potential integration of the energy‐harvesting part into clothing and its connection to other wearable devices by means of fabric wires, PEDOT:PSS coatings, especially on a stretchable substrate such as spandex, are a very attractive option for use on a flexible ferroelectret nanogenerator (FENG). [ 49 ] We recently developed a new screen‐printing scheme for producing highly conductive fabrics via nanotemplate‐assisted PEDOT:PSS phase segregation on the surfaces of fabric fibers. [ 47,54,55 ] Extending phase‐separated PEDOT:PSS coatings to spandex will result in highly stretchable electrodes that are well suitable for all‐organic FENGs.…”

Paper‐Embedded Roll‐to‐Roll Mass Printed Piezoelectric Transducers

“…is required for a completion or full activation of the electronic devices. [15] The same situation can be found when looking for publications dealing with printed ferro-and piezoelectric devices. Typically, these devices on the basis of plastic foil substrates consist of metallic or polymeric electrodes and a piezoelectric polymer (e.g., P(VDF-TrFE)) sandwiched in between several S2S techniques have been used for the realization.…”

Graphene-Based Multifunctional Textile for Sensing and Actuating

“…Thus, the degree of exercise can be evaluated as a health assessment based on the captured signals (Figure d). Figure e shows the radar chart of the GT and other wearable devices ,,, at five dimensions of performance: linearity of the strain/pressure sensors, sound emission ability, ECG detection ability, and fabrication compatibility of the textile. Our device performs well overall.…”

“…Sound is, naturally, a good feedback signal in daily life. Yildirim et al stitched a piezoelectric device to the sleeve of a lab coat, performing as a wearable loudspeaker, but the stretchability of the piezoelectric material is poor. Further, the textile loudspeaker is only used to play music for entertainment, and has not yet been applied in medical alert systems.…”