Chemiresistive gas sensors composed of a thermoplastic polymer matrix and conductive fillers offer various advantages for detecting volatile organic compounds (VOCs), including low power consumption due to near-room-temperature operation, high sensitivity, and inherent selectivity toward VOCs. However, such sensors have a slow response time as the polymer matrix often has a glass transition temperature (T_g) higher than the sensor operating temperature slowing the analyte diffusion to/from the polymer. A plasticizer lowers polymer T_g to match the sensor operation temperature, reducing its response time. In this study, the effect of a plasticizer diethylene glycol dibenzoate (DEGDB) on the sensing properties of polystyrene (PS)-carbon black (CB) composite is investigated to obtain sensors with a fast response time and high sensitivity to VOCs. The sensors are fabricated via drop-on-demand inkjet printing, providing a high degree of control over the sensory film morphology and reproducibility. A design-of-experiment (DoE) approach is adopted to find the optimum ink and print parameters with a minimum number of experiments. As a result, sensors with 30 times faster response time and 25 times higher effective sensitivity are obtained while operating near room temperature (27 °C). Furthermore, the sensors show high sensitivity toward aromatic hydrocarbons (toluene, benzene, and ethylbenzene), with a sub-10 ppm limit of detection (LoD) and a negligible sensitivity toward humidity. Our results show the potential of PS-DEGDB-CB composite as a selective and cost-effective sensory material compatible with large-scale manufacturing techniques for selective near-room-temperature detection of toxic VOCs.

中文翻译：

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利用喷墨打印增塑聚合物复合材料在近室温下检测芳香族化合物

由热塑性聚合物基体和导电填料组成的化学电阻式气体传感器在检测挥发性有机化合物 (VOC) 方面具有多种优势，包括由于接近室温操作而实现的低功耗、高灵敏度以及对 VOC 的固有选择性。然而，此类传感器的响应时间较慢，因为聚合物基质的玻璃化转变温度 ( T _g ) 通常高于传感器工作温度，从而减慢了分析物向/从聚合物的扩散。增塑剂会降低聚合物的T _g以匹配传感器的工作温度，从而缩短其响应时间。在本研究中，研究了增塑剂二甘醇二苯甲酸酯（DEGDB）对聚苯乙烯（PS）-炭黑（CB）复合材料传感性能的影响，以获得对VOCs具有快速响应时间和高灵敏度的传感器。该传感器通过按需喷墨印刷制造，提供对传感膜形态和再现性的高度控制。采用实验设计 (DoE) 方法，以最少的实验次数找到最佳的墨水和印刷参数。因此，传感器在接近室温 (27 °C) 的温度下工作时，响应时间快了 30 倍，有效灵敏度提高了 25 倍。此外，这些传感器对芳香烃（甲苯、苯和乙苯）表现出高灵敏度，检测限 (LoD) 低于 10 ppm，对湿度的灵敏度可忽略不计。我们的结果表明，PS-DEGDB-CB 复合材料作为一种选择性且具有成本效益的传感材料的潜力，与大规模制造技术兼容，用于选择性近室温有毒 VOC 的检测。