Fully flexible and transparent piezoelectric touch sensors based on ZnO nanowires and BaTiO₃ -added SiO₂ capping layers

Abstract

We report on fully flexible and transparent piezoelectric touch sensors based on ZnO nanowires (NWs). Their piezoelectric properties are further enhanced by incorporating BaTiO3 into the capping layer on nanowires. Flexibility is improved by a highly transparent carbon nanotubes–silver nanowires electrode. A BaTiO3‐based capping layer on ZnO nanowires demonstrates a large increase of the output voltage (∼3.3 V) from the touch sensor compared to the voltage (∼50 mV). Mechanical bending tests reveal that the BaTiO3‐added capping layer did not show significant degradation in change of resistance. Our results suggest that the piezoelectric touch sensors are promising for next‐generation flexible touch sensors, wearable, and rollable touch panels.

Physical sensors for skin‐inspired electronics

“…Commonly used piezoelectric materials can be divided into two categories: inorganic (eg, lead zirconate titanate, ZnO, and BaTiO 3 ) and organic (eg, polyvinylidene fluoride [PVDF], P(VDF‐TrFE)). Inorganic piezoelectric materials exhibit high sensitivity but low flexibility.…”

Review of nano piezoelectric devices in biomedicine applications

“…Perovskite piezoelectric materials such as BaTiO 3 are more appealing than ZnO due to their higher piezoelectric constants (Kang et al, 2015; Park et al, 2010). Park et al (2010) reported on a nano harvesters where the integration of BaTiO 3 into thin film formats on substrates was made with soft lithography and transfer printing.…”

“…Piezoelectric devices based on ZnO NWs and capping layers of BaTiO 3 were used by Kang et al (2015) as touch sensors. This is illustrated in Figure 8(a).…”

“…(a) Touch sensor based on ZnO NWs and BaTiO 3 capping layers. (b) Voltage response of the touch sensor (Kang et al, 2015). (c) Photograph of flexible PZT nanoribbon sensor for monitoring cellular deformations.…”

Integrated Piezoelectric AlN Thin Film with SU-8/PDMS Supporting Layer for Flexible Sensor Array

“…A high piezoelectric constant and a low dielectric constant are essential to achieve high sensitivity for piezoelectric MEMS-based devices [14]. Among various piezoelectric thin films, such as aluminum nitride (AlN) [15], ZnO [16], BaTiO 3 [17], lead zirconate titanate (Pb(Zr,Ti)O 3 , PZT) [18] and polyvinylidenefluoride (PVDF) [19], PZT is the most popular due to its high piezoelectric constant, high energy density, and large electrical-mechanical coupling coefficients [12,20]. However, the pressure/touch sensitivity of thin film PZT with regard to voltage response is slightly smaller than that of AlN [21] because of a large dielectric constant-two orders of magnitude higher than that of AlN.…”