Detection of volatile organic compounds (VOCs), challenged by their diversity and similarity, is gaining much attention due to concerns about adverse health effects they cause, along with intensifying development efforts in wireless sensor nodes. Precise identification of volatiles may be subject to the sensitivity and selectivity of a sensor itself and the proximity of the sensor to the source, necessitating power-efficient and portable/wearable sensing systems. The metal-oxide sensors, commonly employed for detection of VOCs, are not power efficient, due to the required heating element, and lack the selectivity, thus reporting only the total VOC level. In this paper, we present a complete low-power wireless gas-sensing system based a capacitive micromachined ultrasonic transducer array, which is known to have several advantages such as high mass sensitivity, easy implementation of a multielement structure, and high selectivity upon polymer coating. We took a holistic approach to designing the sensing elements and the custom integrated circuit (IC) as well as to operating the system, resulting in a small self-contained sensor node (38-mm detect-weight diameter and 16-mm detect-weight height). The chemical-sensing capability of the system has been validated with ethanol, achieving 120-ppb limit-of-detection while the sensor array, including the IC and the power management unit, consuming 80- [Math Processing Error]\mu \text{W} average power with power cycling by actively taking measurements for 3 s detect-weight per minute. The presented system will eventually provide a ubiquitous tool to identify VOCs with the help of multivariate data analysis.

中文翻译：

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在边缘辅助物联网中保持隐私和数据完整性之间的平衡


挥发性有机化合物 (VOC) 的检测因其多样性和相似性而受到挑战，由于担心其对健康造成不利影响，以及无线传感器节点的开发力度不断加大，因此受到广泛关注。挥发物的精确识别可能会受到传感器本身的灵敏度和选择性以及传感器与源的接近程度的影响，因此需要节能且便携式/可穿戴的传感系统。通常用于检测 VOC 的金属氧化物传感器由于需要加热元件而效率不高，并且缺乏选择性，因此只能报告总 VOC 水平。在本文中，我们提出了一种基于电容式微机械超声换能器阵列的完整低功耗无线气体传感系统，该系统具有质量灵敏度高、易于实现多元件结构以及聚合物涂层高选择性等优点。我们采用整体方法来设计传感元件和定制集成电路 (IC) 以及操作系统，从而形成了一个小型独立传感器节点（38 毫米检测重量直径和 16 毫米检测重量）高度）。该系统的化学传感能力已通过乙醇验证，达到 120 ppb 的检测限，而传感器阵列（包括 IC 和电源管理单元）消耗 80- [数学处理误差]\mu \text{ W} 通过每分钟 3 秒主动测量重量进行功率循环的平均功率。所提出的系统最终将提供一个普遍存在的工具，借助多变量数据分析来识别挥发性有机化合物。