Heat-Resistant, Flexible Piezoelectric Sheet Sensors Based on Solution-Processed Zinc Oxide Films for In-Vehicle Driver Monitoring Applications

Abstract

Heat-resistant, low-cost, and large-area flexible piezoelectric sheet sensors that detect the postures of drivers are required for practical driver monitoring systems for vehicles. However, typically used polymer-based piezoelectric materials have low heat resistance. Here, we present a simple heat-resistant piezoelectric sheet sensor based on solution-processed zinc oxide films and discuss its sensing performance. Piezoelectric lithium-doped zinc oxide (Zn1–x Li x O) films are directly prepared on polyimide substrates by a facile solution process, producing relatively large-area sheet sensors with a simple structure and high electrical resistance. The solution-processed Zn1–x Li x O films have a c-axis-oriented wurtzite structure and exhibit an inherent piezoelectric response probably owing to its preferential orientation along the O-polar grains in the self-organized wurtzite films during the formation process. The piezoelectric response of the sheet sensors is unaffected by a heat-resistance test conducted at 393 K. When the sheet sensors are attached to chairs, they are sufficiently sensitive to detect the vital signs (such as respiration and pulse rates), body movements, and countermovements of a seated subject in a laboratory setting. This work demonstrates the feasibility of an unobtrusive driver monitoring system in which heat-resistant piezoelectric sheet sensors are embedded in the seats of future smart vehicles.

Integrated Firefighting Textile with Temperature and Pressure Monitoring for Personal Defense

“…47 We observe a correlation between the aerogel density and the sensing performance (Figure S24), as the lower density of graphene-aerogel fibers leads to the limited capacitance signal under higher applied pressure. 48,49 The graphene-aerogel layer has a high elastic recovery performance, allowing the HSF sensor to respond rapidly and consistently to different loading conditions and mechanical frequencies (Figure S25). The response to relative capacitance changes and compressive strain shows a consistent trend in response to compressive stress, indicating an immediate response to external loads within 150 kPa (Figure S26).…”

“…The high-temperature adaptability of the HSF sensor is of great importance for eliminating sensor error from heat influence, , and a sensing stabilization test is carried out by heating the sensor. Compared to the HSF sensor, layer-structured and stack-structured sensors that also integrate core–sheath composite yarns with the same type of fabric show poor sensing stability over increased temperature without ideal structural stability (Figure a andFigure S28).…”

Synthesis, Optical and D.C Electrical Characterization of (Pomegranate/PVA/TiO2) Ternary-Nanocomposites, As a Window to Improve Solar Cell Performance

“…Absolute zero electrical conductivity is denoted by a value of zero, while the other variables are the Boltzman constant k, the absolute temperature T, the activation energy Ea, the thermal energy KT associated with the change in temperature measured, and the absolute temperature T [11,12] The current-voltage (I-V) Solar cell photovoltaic performance is measured. Voc, Isc, F.F, and η are photovoltaic properties of solar cells), as in the equations below.…”

ZnO/B-g-C3N4 Nanoplatelet/Nanosheet Heterostructures for the Electrochemical Detection of Metol in Real Sample Analysis

“…Among them, ZnO is a promising nanomaterial 13−24 with a broader band gap (3.37 eV) physicochemical properties such as electron mobility and greater exciton BE. 25 It is typically used in solar cells, 26 sensors, 27−29 shortwavelength light emitters, acoustic wave devices, piezoelectric sensors, 30 dye degradation, 31,32 and ultraviolet (UV) laser applications. 33,34 Besides, ZnO has also outstanding chemical stability and good biocompatibility.…”

“…It is typically used in solar cells, sensors, − short-wavelength light emitters, acoustic wave devices, piezoelectric sensors, dye degradation, , and ultraviolet (UV) laser applications. , Besides, ZnO has also outstanding chemical stability and good biocompatibility . In addition, ZnO has an excellent isoelectric point (IPE) about ∼9.5 and to be conductive by decoration/doping into 2D-B-GCN.…”