Associate Laboratory i4HB-Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal.
UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal.
Sensors (Basel). 2023 Mar 28;23(7):3531. doi: 10.3390/s23073531.
Relative humidity (RH) is a common interferent in chemical gas sensors, influencing their baselines and sensitivity, which can limit the performance of e-nose systems. Tuning the composition of the sensing materials is a possible strategy to control the impact of RH in gas sensors. Hybrid gel materials used as gas sensors contain self-assembled droplets of ionic liquid and liquid crystal molecules encapsulated in a polymeric matrix. In this work, we assessed the effect of the matrix hydrophobic properties in the performance of hybrid gel materials for VOC sensing in humid conditions (50% RH). We used two different polymers, the hydrophobic PDMS and the hydrophilic bovine gelatin, as polymeric matrices in hybrid gel materials containing imidazolium-based ionic liquids, [BMIM][Cl] and [BMIM][DCA], and the thermotropic liquid crystal 5CB. Better accuracy of VOC prediction is obtained for the hybrid gels composed of a PDMS matrix combined with the [BMIM][Cl] ionic liquid, and the use of this hydrophobic matrix reduces the effect of humidity on the sensing performance when compared to the gelatin counterpart. VOCs interact with all the moieties of the hybrid gel multicomponent system; thus, VOC correct classification depends not only on the polymeric matrix used, but also on the IL selected, which seems to be key to achieve VOCs discrimination at 50% RH. Thus, hybrid gels' tunable formulation offers the potential for designing complementary sensors for e-nose systems operable under different RH conditions.
相对湿度 (RH) 是化学气体传感器的常见干扰因素，会影响其基线和灵敏度，从而限制电子鼻系统的性能。调整传感材料的组成是控制气体传感器中 RH 影响的一种可行策略。用作气体传感器的混合凝胶材料包含自组装的离子液体液滴和液晶分子，封装在聚合物基质中。在这项工作中，我们评估了基质疏水性对用于在潮湿条件（50% RH）下进行 VOC 感测的混合凝胶材料性能的影响。我们使用了两种不同的聚合物，疏水性 PDMS 和亲水性牛明胶，作为含有基于咪唑的离子液体 [BMIM][Cl] 和 [BMIM][DCA] 和热致液晶 5CB 的混合凝胶材料中的聚合物基质。由 PDMS 基质与 [BMIM][Cl] 离子液体组成的混合凝胶获得了更好的 VOC 预测准确性，与明胶对应物相比，使用这种疏水性基质可以降低湿度对传感性能的影响。VOC 与混合凝胶多组分系统的所有部分相互作用；因此，VOC 的正确分类不仅取决于所用的聚合物基质，还取决于所选的 IL，这似乎是在 50% RH 下实现 VOC 区分的关键。因此，混合凝胶的可调配方为设计可在不同 RH 条件下运行的电子鼻系统的互补传感器提供了潜力。
