The perpetual need for high-performance volatile organic compound (VOC) sensors remains prevalent across diverse sectors including environmental health monitoring, industrial operations, and medical diagnostics. Within this context, the electrostatically formed nanowire (EFN) sensor, a silicon-on-insulator-based multiple-gate field-effect transistor, is an ultrasensitive and selective VOC and gas sensing platform. Unlike conventional silicon nanowires (also known for their superior sensitivity to chemical species), in EFN, the nanowire is defined electrostatically post-fabrication through appropriate biasing of the surrounding gates. The fabrication of the EFN leverages established CMOS compatible silicon processing technologies, facilitating the production of inexpensive, scalable, and robust sensors. By precisely controlling gate biases, a conductive channel with a tunable diameter is formed, allowing for the formation of nanowire with diameter below 20 nm. The adjustable size and shape of the nanowire offer tunable sensing parameters, including sensitivity, limit of detection, and dynamic range. The multiple parameters also yield a unique fingerprint for each VOC, thus enabling selective detection of VOCs. By simply altering the biasing configuration, a single EFN sensor can achieve high sensitivity and a broad dynamic range, which is limited in the case of physically defined silicon NW sensors. This review provides a comprehensive overview encompassing the EFN sensor's design, fabrication considerations, process flow, electrical characterization methods, sensing performances to VOCs, and gases at room temperature. Moreover, the scope of advanced sensor designs with array of EFN sensors and integrated heaters is also discussed. Finally, some future perspectives of this technology are presented.

中文翻译：

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静电形成的纳米线 (EFN) 晶体管——超灵敏 VOC 和气体传感器

环境健康监测、工业运营和医疗诊断等各个领域对高性能挥发性有机化合物 (VOC) 传感器的持续需求仍然普遍存在。在此背景下，静电形成的纳米线 (EFN) 传感器是一种基于绝缘体上硅的多栅极场效应晶体管，是一种超灵敏、选择性的 VOC 和气体传感平台。与传统的硅纳米线（也因其对化学物质的卓越敏感性而闻名）不同，在 EFN 中，纳米线是通过对周围栅极进行适当的偏置在制造后进行静电定义的。 EFN 的制造利用了成熟的 CMOS 兼容硅处理技术，有助于生产廉价、可扩展且坚固的传感器。通过精确控制栅极偏置，形成直径可调的导电沟道，从而形成直径低于20 nm的纳米线。纳米线的可调节尺寸和形状提供了可调节的传感参数，包括灵敏度、检测限和动态范围。多个参数还为每种 VOC 生成独特的指纹，从而实现 VOC 的选择性检测。通过简单地改变偏置配置，单个 EFN 传感器可以实现高灵敏度和宽动态范围，这在物理定义的硅纳米线传感器的情况下是有限的。本综述提供了全面的概述，涵盖 EFN 传感器的设计、制造注意事项、工艺流程、电气表征方法、VOC 和室温气体的传感性能。此外，还讨论了采用 EFN 传感器阵列和集成加热器的先进传感器设计的范围。最后，提出了该技术的一些未来前景。