Choi Woo Suk, Jung Kyung Hoon, Hong Hyun Pyo, Lee Myung Jin, Min Nam Ki
Department of Biomicrosystem Technology, Korea University, Seoul, Sungbuk-Ku, 136-713, Korea.
J Nanosci Nanotechnol. 2013 Sep;13(9):6400-4. doi: 10.1166/jnn.2013.7620.
Improving the response time for polyimide (PI)-based capacitive humidity sensors is critical for real-time sensing. Multi-walled carbon nanotube (MWCNT) films were used to form the upper electrode of humidity sensor to realize an extremely short response times. MWCNT films were spray-deposited on a moisture-sensitive PI layer and subsequently patterned by oxygen plasma. Random-network MWCNT electrodes have a well-entangled and open porous structure that is almost impossible to obtain with conventional metal electrodes. Compared with porous metal electrode-based sensors as an upper electrode, the fabricated capacitive humidity sensors with MWCNT electrodes showed an exceptionally short response time of less than 2.5 s and a good linearity of 0.998. An analysis of the long-term (100 days) stability data revealed that the MWCNT electrode humidity sensors showed little drift even after 100 days aging, indicating that they are suitable for practical and reliable humidity measurements. These improvements in performance may stem from their interconnected microscopic porous structure, which is more accessible to water molecules through the conductive electrode.
提高基于聚酰亚胺（PI）的电容式湿度传感器的响应时间对于实时传感至关重要。多壁碳纳米管（MWCNT）薄膜被用于形成湿度传感器的上电极，以实现极短的响应时间。MWCNT薄膜通过喷雾沉积在对湿度敏感的PI层上，随后通过氧等离子体进行图案化处理。随机网络MWCNT电极具有良好的缠结和开放多孔结构，这几乎是传统金属电极无法实现的。与以多孔金属电极作为上电极的传感器相比，所制备的带有MWCNT电极的电容式湿度传感器表现出异常短的响应时间，小于2.5秒，并且具有0.998的良好线性度。对长期（100天）稳定性数据的分析表明，MWCNT电极湿度传感器即使经过100天老化也几乎没有漂移，这表明它们适用于实际且可靠的湿度测量。这些性能上的改进可能源于其相互连接的微观多孔结构，水分子通过导电电极更容易进入该结构。
