Piezoresistive Nanomechanical Humidity Sensors Using Internal Stress In-Plane of Si-Polymer Composite Membranes
| Autor: | Krzysztof Moorthi, Takahito Ono, Md. Mahabub Hossain, Takumi Hokama, Mai Yamazaki, Masaya Toda |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
chemistry.chemical_classification Fabrication Materials science Silicon Composite number chemistry.chemical_element 02 engineering and technology Polymer 021001 nanoscience & nanotechnology 01 natural sciences Piezoresistive effect Stress (mechanics) chemistry Etching (microfabrication) 0103 physical sciences Relative humidity Electrical and Electronic Engineering Composite material 0210 nano-technology Instrumentation |
| Zdroj: | IEEE Sensors Letters. 3:1-4 |
| ISSN: | 2475-1472 |
| DOI: | 10.1109/lsens.2019.2893298 |
| Popis: | This article presents the design and fabrication process of a highly miniaturized nanomechanical Si-polymer composite membrane-type internal-stress sensor (MIS) with piezoresistive elements for humidity detection. The 500-μm2 area dimension sensor consists of a thin Si-polymer composite membrane supported by two piezoresistive Si beams. The composite membrane is fabricated as follows: First, 1-μm-wide width Si slits with 1 μm separation gaps are formed by using photolithography and deep reactive-ion etching, and then, the Si slits are filled with a functional polymer (methyl methacrylate based acrylate resin: OLESTERTMQ155). This composite device acts as an absorber of vapor molecules and, consequently, generates stress. The fabricated sensor in a humidity-controlled chamber shows a relative resistance change Δ R / R device = 0.6% for 58% relative humidity (RH) change and a highly linear steady response of 5.2 mV/%RH up to 70% RH change with sensing resolution of 0.5% humidity. The measured polymer expansion ratio of ep = 2.4 × 10−3 is consistent with the theoretical estimation using the weight fraction of water adsorbed in the polymer. |
| Databáze: | OpenAIRE |
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