A nanohybrid piezoelectric strain sensor was fabricated by growing vertically aligned (0001)-oriented crystalline zinc oxide nanowires directly on graphene (ZnO-VANWs/Gr) using a facile seedless hydrothermal process. Under mechanical strains, the induced piezoelectric effect on the ZnO-VANWs transduces to a piezoelectric gating effect at the ZnO-VANWs/Gr interface, resulting in a modulation of the conductivity of the Gr channel through electrostatic doping. The vertical alignment of the (0001)-oriented ZnO-VANWs on Gr is ideal to achieving high strain sensitivity, and a low-defect ZnO-VANWs/Gr interface obtained in the seedless hydrothermal process is key to realizing high sensitivity and fast response. Indeed, a high sensitivity up to 3.15 × 10^–2 kPa^–1 was obtained on the ZnO-VANWs/Gr strain sensors at lower pressures of 1.1 × 10^–6–11 Torr, together with a fast response time of ∼0.10 s. In particular, these results represent enhancement factors of ∼7 and 8, respectively, as compared to strain sensors of a similar structure, except having a polycrystalline ZnO seed layer on Gr for the growth of ZnO-VANWs. Therefore, our result illustrates the critical importance of the low-defect interface of the ZnO-VANWs with Gr formed in the seedless ZnO-VANW growth for realizing an optimal electrostatic gating of Gr. In addition, the ZnO-VANWs/Gr nanohybrids can be readily scaled up using the seedless hydrothermal process for commercial applications in optoelectronics and sensors.

中文翻译：

---

基于垂直排列的压电氧化锌纳米线阵列/石墨烯纳米混合体的高性能应变传感器

通过使用简便的无籽水热工艺，在石墨烯上直接生长垂直排列的（0001）取向的结晶氧化锌纳米线（ZnO-VANWs / Gr），制造出纳米混合压电应变传感器。在机械应变下，对ZnO-VANWs的感应压电效应会转换为ZnO-VANWs / Gr界面的压电门控效应，从而通过静电掺杂来调节Gr通道的电导率。（0001）取向的ZnO-VANWs在Gr上的垂直排列是实现高应变敏感性的理想选择，在无籽水热工艺中获得的低缺陷ZnO-VANWs / Gr界面是实现高敏感性和快速响应的关键。确实，高达3.15×10 ^–2 kPa ^–1的高灵敏度在ZnO-VANWs / Gr应变传感器上获得的压力在1.1×10 ^–6 –11 Torr的较低压力下获得，且响应时间约为〜0.10 s。特别是，与具有类似结构的应变传感器相比，这些结果分别表示约7和8的增强因子，不同之处在于在Gr上具有用于生长ZnO-VANW的多晶ZnO籽晶层。因此，我们的结果说明了在无籽ZnO-VANW生长中形成的具有Gr的ZnO-VANW的低缺陷界面对于实现Gr的最佳静电门控至关重要。此外，ZnO-VANWs / Gr纳米杂化物可使用无籽水热工艺轻松扩大规模，用于光电和传感器的商业应用。