Chung Chen-Kuei, Ku Chin-An
Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Micromachines (Basel). 2023 Jun 29;14(7):1330. doi: 10.3390/mi14071330.
With the increases in work environment regulations restricting alcohol to 1000 ppm, and in drink-driving laws, testing for alcohol with a simple method is a crucial issue. Conventional alcohol sensors based on sulfide, metal oxide, boron nitride or graphene oxide have a detection limit in the range of 50-1000 ppm but have disadvantages of complicated manufacture and longer processing times. A recent portable alcohol meter based on semiconductor material using conductivity or chemistry measurements still has the problem of a complex and lengthy manufacturing process. In this paper, a simple and effective resistive-type alcohol vapor sensor using one-step anodic aluminum oxide (AAO) is proposed. The nanoporous AAO was produced in one-step by anodizing low-purity AA1050 at room temperature of 25 °C, which overcame the traditional high-cost and lengthy process at low temperature of anodization and etching from high-purity aluminum. The highly specific surface area of AAO has benefits for good sensing performance, especially as a humidity or alcohol vapor sensor. With the resistance measurement method, alcohol vapor concentration of 0, 100, 300, 500, 700 and 1000 ppm correspond to mean resistances of 8524 Ω, 8672 Ω, 9121 Ω, 9568 Ω, 10,243 Ω, and 11,045 Ω, respectively, in a linear relationship. Compared with other materials for detecting alcohol vapor, the AAO resistive sensor has advantages of fast and simple manufacturing with good detection limits for practical applications. The resistive-type alcohol vapor-sensing mechanism is described with respect to the resistivity of the test substance and the pore morphology of AAO. In a human breath test, the AAO sensor can quickly distinguish whether the subject is drinking, with normal breath response of -30% to -40% and -20% to -30% response after drinking 50 mL of wine of 25% alcohol.
随着工作环境法规将酒精限制在1000 ppm以内以及酒驾法律的实施，采用简单方法检测酒精成为一个关键问题。基于硫化物、金属氧化物、氮化硼或氧化石墨烯的传统酒精传感器检测限在50 - 1000 ppm范围内，但存在制造复杂和处理时间长的缺点。最近基于半导体材料利用电导率或化学测量的便携式酒精计仍存在制造过程复杂且冗长的问题。本文提出了一种使用一步法阳极氧化铝（AAO）的简单有效的电阻式酒精蒸汽传感器。通过在25℃室温下对低纯度AA1050进行阳极氧化一步制备出纳米多孔AAO，克服了传统从高纯度铝进行低温阳极氧化和蚀刻的高成本和冗长工艺。AAO的高比表面积有利于良好的传感性能，特别是作为湿度或酒精蒸汽传感器。采用电阻测量方法时，0、100、300、500、700和1000 ppm的酒精蒸汽浓度分别对应平均电阻8524Ω、8672Ω、9121Ω、9568Ω、10243Ω和11045Ω，呈线性关系。与其他用于检测酒精蒸汽的材料相比，AAO电阻式传感器具有制造快速简单且在实际应用中检测限良好的优点。针对测试物质的电阻率和AAO的孔形态描述了电阻式酒精蒸汽传感机制。在人体呼气测试中，AAO传感器能快速区分受试者是否饮酒，正常呼气响应为 - 30%至 - 40%，饮用50 mL酒精含量为25%的葡萄酒后响应为 - 20%至 - 30%。
