Porous Piezoelectric Single Crystal Sensors (POPSICALS)

压电材料在机械应力作用下产生电荷。这些特性使其成为压力传感器、医疗换能器和振动能量采集器的重要材料，预计到2025年，其市场规模将达到280亿英镑。目前的商业材料基于致密陶瓷，因为它们在机械应力下产生高电荷。然而，它们也有一系列的缺点。(i)目前的材料是铅基的，如锆钛酸铅（PZT），每年产生2500多吨含铅电子废物；（ii）现有材料密度高，刚度高；导致与生物组织或水的阻抗匹配不良，（iii）致密材料的高介电常数导致传感和收获性能差，因为性能指标与介电常数成反比，（iv）陶瓷元件只能以有限的几何形状生产，因为它们是通过压制陶瓷粉末和随后的高温烧结制成的。popsic将通过开发一种基于磁场增强冷冻铸造工艺的新制造工艺来制造单晶状无铅多孔压电材料，从而克服现有陶瓷的缺点。这将把单晶材料的高压电电荷系数与多孔材料的低介电常数、低密度和低刚度结合起来。

Piezoelectric materials generate an electrical charge in response to mechanical stress. These properties make them important materials for pressure sensors, medical transducers and vibration energy harvesters and the market is estimated to be £28 billion by 2025. Current commercial materials are based on dense ceramics since they generate a high charge in response to mechanical stress. However, they have a range of disadvantages.(i) current materials are lead-based, such as lead zirconate titanate (PZT), and generate over 2500 tons of lead electronic waste per annum,(ii) existing materials are high density and high stiffness, leading to poor impedance matching with biological tissue or water,(iii) the high permittivity of dense materials leads to poor performance for sensing and harvesting since performance indicators are inversely proportional to permittivity,(iv) ceramic elements can only be produced in limited geometries since they are made by pressing ceramic powders and subsequent high-temperature sintering.POPSICALS will overcome the disadvantages of existing ceramics by developing a new manufacturing process based on a magnetic field enhanced freeze-casting process to create single crystal-like lead-free porous piezoelectric materials. This will combine the high piezoelectric charge coefficients of single-crystal materials with the low permittivity, low density and low stiffness of porous materials.