Santos Ana R, Viana Júlio C
IPC-Institute for Polymers and Composites, University of Minho, 4804-533 Guimarães, Portugal.
Nanomaterials (Basel). 2024 Oct 15;14(20):1653. doi: 10.3390/nano14201653.
The exponential demand for real-time monitoring applications has altered the course of sensor development, from sensor electronics miniaturization, e.g., resorting to printing techniques, to low-cost, flexible and functional wearable materials. Humidity sensing has been used in the prevention and diagnosis of medical conditions, as well as in the assessment of physical comfort. This paper presents a resistive flexible humidity sensor composed of silver interdigitated electrodes (IDTs) screen printed onto polyimide film and an active layer of multiwall carbon nanotubes (MWCNT) dispersed in a water-soluble polymer, polyvinyl alcohol (PVA). Different MWCNT/PVA sensor sizes and MWCNT percentages are tested to study their effect on the initial electrical resistance (R) values and sensor response at different humidity percentages. The results show that the R values decrease with the increase in % MWCNT. The sensor size did not influence the sensor response, while the % MWCNT affected the sensor behavior upon relative humidity (RH) increments. The 1% MWCNT/PVA sensor showed the best response, reaching a relative electrical resistance, ΔR/R, of 509% at 99% RH. Comparable with other reported sensors, the produced MWCNT/PVA flexible sensor is simpler, greener and shows a good sensitivity to humidity, being easily incorporated in wearable monitoring applications, from sports to medical fields.
对实时监测应用的指数级需求改变了传感器的发展方向，从传感器电子元件的小型化，例如采用印刷技术，到低成本、灵活且功能化的可穿戴材料。湿度传感已被用于医疗状况的预防和诊断，以及身体舒适度的评估。本文介绍了一种电阻式柔性湿度传感器，它由丝网印刷在聚酰亚胺薄膜上的银叉指电极（IDT）和分散在水溶性聚合物聚乙烯醇（PVA）中的多壁碳纳米管（MWCNT）活性层组成。测试了不同的MWCNT/PVA传感器尺寸和MWCNT百分比，以研究它们对初始电阻（R）值以及在不同湿度百分比下传感器响应的影响。结果表明，R值随MWCNT百分比的增加而降低。传感器尺寸不影响传感器响应，而MWCNT百分比在相对湿度（RH）增加时会影响传感器性能。1% MWCNT/PVA传感器表现出最佳响应，在99% RH时相对电阻ΔR/R达到509%。与其他报道的传感器相比，所制备的MWCNT/PVA柔性传感器更简单、更环保，并且对湿度具有良好的灵敏度，易于应用于从运动到医疗领域的可穿戴监测应用中。
