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ZnO Nanowire-based Capacitive Humidity Sensor Integrated on a Polyimide Layer with a Micro-heater
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- Authors
- Jaewoo Lee, J. Im, J.H. Kim, S.-Y. Lim, E.B. Jeon, S. M. Moon
- Issue Date
- 2018-11
- Citation
- International Conference and Exhibition for Nanotechnology (NANOPIA) 2018, pp.1-1
- Language
- English
- Type
- Conference Paper
- Abstract
- For environmental monitoring in IoT application, a compact ZnO nanowire-based capacitive-type relative humidity (RH) sensor is presented, which has a circular-shaped diameter of 100 μm and a chip size of 1 mm 2 as shown in Fig 1(a). After fully compatible CMOS-MEMS process, the nanowires were finally formed on the interdigited transducers (IDT) with a space of 4 μm by using the hydrothermal method of 80 o C. The humidity sensor was located on a patterned 2.0 um-polyimide layer with a low thermal conductivity of 0.12 W/mK in order to detect rapidly deviation. Additionally, it was integrated on a microheater of Ti/Al/TiN layers (0.3 μm), showing that it enables reacted water molecules to be detached from sensing materials. The sensor was characterized with the impedance analyzer in the range of 45 kHz to 55 kHz owing to minimum noise interference. As shown in Fig 1(b), by measuring capacitance change at the condition of one human breath for one second, the responsivity was determined to 35 % on the comparison to that of 50 % relative humidity, resulting in the fast response within 2 second.
- KSP Keywords
- CMOS-MEMS, Capacitive-type, Environmental monitoring, IOT applications, Impedance analyzer, Low thermal conductivity, MEMS process, Micro-heater, Minimum Noise, Polyimide layer, Relative Humidity